Excluding the Supernatural

Followup toReductionism, Anthropomorphic Optimism

Occasionally, you hear someone claiming that creationism should not be taught in schools, especially not as a competing hypothesis to evolution, because creationism is a priori and automatically excluded from scientific consideration, in that it invokes the "supernatural".

So... is the idea here, that creationism could be true, but even if it were true, you wouldn't be allowed to teach it in science class, because science is only about "natural" things?

It seems clear enough that this notion stems from the desire to avoid a confrontation between science and religion.  You don't want to come right out and say that science doesn't teach Religious Claim X because X has been tested by the scientific method and found false.  So instead, you can... um... claim that science is excluding hypothesis X a priori.  That way you don't have to discuss how experiment has falsified X a posteriori.

Of course this plays right into the creationist claim that Intelligent Design isn't getting a fair shake from science—that science has prejudged the issue in favor of atheism, regardless of the evidence.  If science excluded Intelligent Design a priori, this would be a justified complaint!

But let's back up a moment.  The one comes to you and says:  "Intelligent Design is excluded from being science a priori, because it is 'supernatural', and science only deals in 'natural' explanations."

What exactly do they mean, "supernatural"?  Is any explanation invented by someone with the last name "Cohen" a supernatural one?  If we're going to summarily kick a set of hypotheses out of science, what is it that we're supposed to exclude?

By far the best definition I've ever heard of the supernatural is Richard Carrier's:  A "supernatural" explanation appeals to ontologically basic mental things, mental entities that cannot be reduced to nonmental entities.

This is the difference, for example, between saying that water rolls downhill because it wants to be lower, and setting forth differential equations that claim to describe only motions, not desires.  It's the difference between saying that a tree puts forth leaves because of a tree spirit, versus examining plant biochemistry.  Cognitive science takes the fight against supernaturalism into the realm of the mind.

Why is this an excellent definition of the supernatural?  I refer you to Richard Carrier for the full argument.  But consider:  Suppose that you discover what seems to be a spirit, inhabiting a tree: a dryad who can materialize outside or inside the tree, who speaks in English about the need to protect her tree, et cetera.  And then suppose that we turn a microscope on this tree spirit, and she turns out to be made of parts—not inherently spiritual and ineffable parts, like fabric of desireness and cloth of belief; but rather the same sort of parts as quarks and electrons, parts whose behavior is defined in motions rather than minds.  Wouldn't the dryad immediately be demoted to the dull catalogue of common things?

But if we accept Richard Carrier's definition of the supernatural, then a dilemma arises: we want to give religious claims a fair shake, but it seems that we have very good grounds for excluding supernatural explanations a priori.

I mean, what would the universe look like if reductionism were false?

I previously defined the reductionist thesis as follows: human minds create multi-level models of reality in which high-level patterns and low-level patterns are separately and explicitly represented.  A physicist knows Newton's equation for gravity, Einstein's equation for gravity, and the derivation of the former as a low-speed approximation of the latter.  But these three separate mental representations, are only a convenience of human cognition.  It is not that reality itself has an Einstein equation that governs at high speeds, a Newton equation that governs at low speeds, and a "bridging law" that smooths the interface.  Reality itself has only a single level, Einsteinian gravity.  It is only the Mind Projection Fallacy that makes some people talk as if the higher levels could have a separate existence—different levels of organization can have separate representations in human maps, but the territory itself is a single unified low-level mathematical object.

Suppose this were wrong.

Suppose that the Mind Projection Fallacy was not a fallacy, but simply true.

Suppose that a 747 had a fundamental physical existence apart from the quarks making up the 747.

What experimental observations would you expect to make, if you found yourself in such a universe?

If you can't come up with a good answer to that, it's not observation that's ruling out "non-reductionist" beliefs, but a priori logical incoherence.  If you can't say what predictions the "non-reductionist" model makes, how can you say that experimental evidence rules it out?

My thesis is that non-reductionism is a confusion; and once you realize that an idea is a confusion, it becomes a tad difficult to envision what the universe would look like if the confusion were true.  Maybe I've got some multi-level model of the world, and the multi-level model has a one-to-one direct correspondence with the causal elements of the physics?  But once all the rules are specified, why wouldn't the model just flatten out into yet another list of fundamental things and their interactions?  Does everything I can see in the model, like a 747 or a human mind, have to become a separate real thing?  But what if I see a pattern in that new supersystem?

Supernaturalism is a special case of non-reductionism, where it is not 747s that are irreducible, but just (some) mental things.  Religion is a special case of supernaturalism, where the irreducible mental things are God(s) and souls; and perhaps also sins, angels, karma, etc.

If I propose the existence of a powerful entity with the ability to survey and alter each element of our observed universe, but with the entity reducible to nonmental parts that interact with the elements of our universe in a lawful way; if I propose that this entity wants certain particular things, but "wants" using a brain composed of particles and fields; then this is not yet a religion, just a naturalistic hypothesis about a naturalistic Matrix.  If tomorrow the clouds parted and a vast glowing amorphous figure thundered forth the above description of reality, then this would not imply that the figure was necessarily honest; but I would show the movies in a science class, and I would try to derive testable predictions from the theory.

Conversely, religions have ignored the discovery of that ancient bodiless thing: omnipresent in the working of Nature and immanent in every falling leaf: vast as a planet's surface and billions of years old: itself unmade and arising from the structure of physics: designing without brain to shape all life on Earth and the minds of humanity.  Natural selection, when Darwin proposed it, was not hailed as the long-awaited Creator:  It wasn't fundamentally mental.

But now we get to the dilemma: if the staid conventional normal boring understanding of physics and the brain is correct, there's no way in principle that a human being can concretely envision, and derive testable experimental predictions about, an alternate universe in which things are irreducibly mental.  Because, if the boring old normal model is correct, your brain is made of quarks, and so your brain will only be able to envision and concretely predict things that can predicted by quarks.  You will only ever be able to construct models made of interacting simple things.

People who live in reductionist universes cannot concretely envision non-reductionist universes.  They can pronounce the syllables "non-reductionist" but they can't imagine it.

The basic error of anthropomorphism, and the reason why supernatural explanations sound much simpler than they really are, is your brain using itself as an opaque black box to predict other things labeled "mindful".  Because you already have big, complicated webs of neural circuitry that implement your "wanting" things, it seems like you can easily describe water that "wants" to flow downhill—the one word "want" acts as a lever to set your own complicated wanting-machinery in motion.

Or you imagine that God likes beautiful things, and therefore made the flowers.  Your own "beauty" circuitry determines what is "beautiful" and "not beautiful".  But you don't know the diagram of your own synapses.  You can't describe a nonmental system that computes the same label for what is "beautiful" or "not beautiful"—can't write a computer program that predicts your own labelings.  But this is just a defect of knowledge on your part; it doesn't mean that the brain has no explanation.

If the "boring view" of reality is correct, then you can never predict anything irreducible because you are reducible.  You can never get Bayesian confirmation for a hypothesis of irreducibility, because any prediction you can make is, therefore, something that could also be predicted by a reducible thing, namely your brain.

Some boxes you really can't think outside.  If our universe really is Turing computable, we will never be able to concretely envision anything that isn't Turing-computable—no matter how many levels of halting oracle hierarchy our mathematicians can talk about, we won't be able to predict what a halting oracle would actually say, in such fashion as to experimentally discriminate it from merely computable reasoning.

Of course, that's all assuming the "boring view" is correct.  To the extent that you believe evolution is true, you should not expect to encounter strong evidence against evolution.  To the extent you believe reductionism is true, you should expect non-reductionist hypotheses to be incoherent as well as wrong.  To the extent you believe supernaturalism is false, you should expect it to be inconceivable as well.

If, on the other hand, a supernatural hypothesis turns out to be true, then presumably you will also discover that it is not inconceivable.

So let us bring this back full circle to the matter of Intelligent Design:

Should ID be excluded a priori from experimental falsification and science classrooms, because, by invoking the supernatural, it has placed itself outside of natural philosophy?

I answer:  "Of course not."  The irreducibility of the intelligent designer is not an indispensable part of the ID hypothesis.  For every irreducible God that can be proposed by the IDers, there exists a corresponding reducible alien that behaves in accordance with the same predictions—since the IDers themselves are reducible; to the extent I believe reductionism is in fact correct, which is a rather strong extent, I must expect to discover reducible formulations of all supposedly supernatural predictive models.

If we're going over the archeological records to test the assertion that Jehovah parted the Red Sea out of an explicit desire to display its superhuman power, then it makes little difference whether Jehovah is ontologically basic, or an alien with nanotech, or a Dark Lord of the Matrix.  You do some archeology, find no skeletal remnants or armor at the Red Sea site, and indeed find records that Egypt ruled much of Canaan at the time.  So you stamp the historical record in the Bible "disproven" and carry on.  The hypothesis is coherent, falsifiable and wrong.

Likewise with the evidence from biology that foxes are designed to chase rabbits, rabbits are designed to evade foxes, and neither is designed "to carry on their species" or "protect the harmony of Nature"; likewise with the retina being designed backwards with the light-sensitive parts at the bottom; and so on through a thousand other items of evidence for splintered, immoral, incompetent design.  The Jehovah model of our alien god is coherent, falsifiable, and wrong—coherent, that is, so long as you don't care whether Jehovah is ontologically basic or just an alien.

Just convert the supernatural hypothesis into the corresponding natural hypothesis.  Just make the same predictions the same way, without asserting any mental things to be ontologically basic.  Consult your brain's black box if necessary to make predictions—say, if you want to talk about an "angry god" without building a full-fledged angry AI to label behaviors as angry or not angry.  So you derive the predictions, or look up the predictions made by ancient theologians without advance knowledge of our experimental results.  If experiment conflicts with those predictions, then it is fair to speak of the religious claim having been scientifically refuted.  It was given its just chance at confirmation; it is being excluded a posteriori, not a priori.

Ultimately, reductionism is just disbelief in fundamentally complicated things.  If "fundamentally complicated" sounds like an oxymoron... well, that's why I think that the doctrine of non-reductionism is a confusion, rather than a way that things could be, but aren't.  You would be wise to be wary, if you find yourself supposing such things.

But the ultimate rule of science is to look and see.  If ever a God appeared to thunder upon the mountains, it would be something that people looked at and saw.

Corollary:  Any supposed designer of Artificial General Intelligence who talks about religious beliefs in respectful tones, is clearly not an expert on reducing mental things to nonmental things; and indeed knows so very little of the uttermost basics, as for it to be scarcely plausible that they could be expert at the art; unless their idiot savancy is complete.  Or, of course, if they're outright lying.  We're not talking about a subtle mistake.

 

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My point was that vampires were by definition not real - or at least, not understandable - because any time we found something real and understandable that met the definition of a vampire, we would change the definition to exclude it.

But the same exchange might have occurred with something entirely real. We are not in the habit of giving fully adequate definitions, so it is often possible to find counterexamples to the definitions we give, which might prompt the other person to add to the definition to exclude the counterexample. For example:

A: What is a dog?

B: A dog is a four-footed animal that is a popular pet.

A: So a cat is a dog.

B: Dogs bark.

A: So if I teach a cat to bark, it will become a dog.

etc.

I had a similar, shorter conversation with a theologian. He had hired me to critique a book he was writing, which claimed that reductionist science had reached its limits, and that it was time to turn to non-reductionist science.

The examples he gave were all phenomena which science had difficulty explaining, and which he claimed to explain as being irreducibly complex. For instance, because people had difficulty explaining how cells migrate in a developing fetus, he suggested (as Aristotle might have) that the cells had an innate fate or desire that led them to the right location.

What he really meant by non-reductionist science, was that as a "non-reductionist scientist", one is allowed to throw up one's hands, and say that there is no explanation for something. A claim that a phenomenon is supernatural is always the assertion that something has no explanation. (I don't know that it needs to be presented as a mental phenomenon, as Eliezer says.) So to "do" non-reductionist science is simply to not do science.

It should be possible, then, for a religious person to rightly claim that their point of view is outside the realm of science. If they said, for instance, that lightning is a spirit, that is not a testable hypothesis.

In practice, religions build up webs of claims, and of connections to the non-spiritual world, that can be tested for consistency. If someone claims not just that lightning is a spirit, but that an anthropomorphic God casts lightning bolts at sinners, that is a testable hypothesis. Once, when I was a Christian, lightning struck the cross behind my church. This struck me as strong empirical evidence against the idea that God directed every bolt. (I suppose one could interpret it as divine criticism of the church. The church elders did not, however, pursue that angle.)

What he really meant by non-reductionist science, was that as a "non-reductionist scientist", one is allowed to throw up one's hands, and say that there is no explanation for something.

No. Good scientists say that there are no current explanations all the time. The non-reductionist claims to know that there can't ever be an explanation. That's the opposite of throwing up your hands and saying you don't have an explanation. That's a claim to know that all possible explanations will fail.

What he really meant by non-reductionist science, was that as a "non-reductionist scientist", one is allowed to throw up one's hands, and say that there is no explanation for something.

beat

No. Good scientists say that there are no current explanations all the time. The non-reductionist claims to know that there can't ever be an explanation. That's the opposite of throwing up your hands and saying you don't have an explanation. That's a claim to know that all possible explanations will fail.

You tried to make a contradiction, but you ended up saying exactly the same thing. "There is no explanation," means no explanation exists, which is the nonsense position that Phil attacked three years ago. "We don't have an explanation yet," is entirely sensible, of course, which is why that position has never been attacked by anyone, ever.

No explanation exists for why there is lint in my belly button. No one has explained it, even to themselves. Now, if we think about it, we may come up with an explanation, but that doesn't mean the explanation exists now, anymore than a house we might build exists now because we might build it.

No explanation exists for X <> there can never be an explanation for X.

I have a feeling "no explanation exists" was meant in the mathematical sense of "exists". Which means exactly that there is no possible string of characters that is an explanation for X.

Once, in a LARP, I played Isaac Asimov on a panel which was arguing whether vampires were real. It went something like this (modulo my memory): I asked the audience to define "vampire", and they said that vampires were creatures that lived by drinking blood.

I said that mosquitoes were vampires. So they said that vampires were humanoids who lived by drinking blood.

I said that Masai who drank the blood of their cattle were vampires. So they said that vampires were humanoids who lived by drinking blood, and were burned by sunlight.

I (may have) said that a Masai with xeroderma pigmentosum was a vampire. And so on.

My point was that vampires were by definition not real - or at least, not understandable - because any time we found something real and understandable that met the definition of a vampire, we would change the definition to exclude it.

(Strangely, some mythical creatures, such as vampires and unicorns, seem to be defined in a spiritual way; whereas others, such as mermaids and centaurs, do not. A horse genetically engineered to grow a horn would probably not be thought of as a "real" unicorn; a genenged mermaid probably would be admitted to be a "real" mermaid.)

My point was that vampires were by definition not real - or at least, not understandable - because any time we found something real and understandable that met the definition of a vampire, we would change the definition to exclude it.

Nonsense. If there was a creature that:

  • Used to be a normal living human
  • Still looks human
  • Has the same internal organs but none of them are functioning
  • Isn't vulnerable to hemlock
  • Has more strength than could plausibly attributed to humans according to our understanding of genetics
  • Has teeth which extend to fangs and then retract.
  • Can only be sustained by blood.
  • Definitely doesn't glitter. Ever.
  • Physically cannot enter people's houses due to physical restraint that seems to be only operating on the creature. Exception - can enter people's houses if invited.
  • Starts behaving like the human that they used to be except with extreme sociopathic and homicidal tendencies.
  • Is unaffected by getting stabbed in the chest by anything but a wooden stake. (Wooden stake kills him.)
  • Burns when exposed to sunlight, holy water or religious symbols.
  • Instantly turns to dust when staked, decapitated or sufficiently burnt via the aforementioned causes.

... then basically everyone would agree it was a vampire. LARPy Asimov is just being annoying when he tries to spin the question about the universe into a question about semantics.

  • Definitely doesn't glitter. Ever.

... then basically everyone would agree it was a vampire.

Except some Twilight fans.

My point was that vampires were by definition not real - or at least, not understandable - because any time we found something real and understandable that met the definition of a vampire, we would change the definition to exclude it.

Daniel Dennett has a cute one like this. Real Magic (the kind in Vegas) is not Real Magic (Abracadabra shazam poof!).

I think my first encounter with this was James Randi, which makes a lot of sense. I don't know if it was originally his, either, though.

Found the quote the other day. Makes sense that Randi knew it too. Apparently Siegel was a magician and professor too, who wrote a book on Indian magic.

youtube, Free Will as Moral Competence, Daniel Dennett at the University of Melbourne, Australia, 15:21 Dennett quotes from "Net of Magic", by Lee Siegel

Quote from book: "I'm writing a book on magic, " I explain, and I'm asked, "Real magic?" By real magic people mean miracles, thaumaturgical acts, and supernatural powers. "No, " I answer: "Conjuring tricks, not real magic."

Dennett: Real magic, in other words, refers to the magic that is not real, while the magic that is real, that can actually be done, is not real magic.

Dennett: Real magic, in other words, refers to the magic that is not real, while the magic that is real, that can actually be done, is not real magic.

That's the same quirk in natural language by which a heavy drinker is not usually a drinker who weighs a lot. ( can mean ‘a who/which is ’, or ‘someone/something who/which is ly a ’.)

Thank you for articulating my problem with the "real magic" quote.

Surely real magic is done through yet-unknown means. It might stop being magical some day, once explained (reduced), in compliance with Clarke's 3rd law.

The key issue seems to not be the fiction but that the elements creating your "vampire" are separate. Your Masai with xeroderma pigmentosum has vampiric properties because of distinct separate events. If there were say a single virus that made people both have a similar light aversion and made them desire blood, I don't think most people would have a problem calling them vampires.

Indeed, I would not object to being called a vampire if I had porphyria. (I was going to write “call someone a vampire if they have”, but I realize they might conceivably find it offensive.)

(Strangely, some mythical creatures, such as vampires and unicorns, seem to be defined in a spiritual way; whereas others, such as mermaids and centaurs, do not. A horse genetically engineered to grow a horn would probably not be thought of as a "real" unicorn; a genenged mermaid probably would be admitted to be a "real" mermaid.)

Dunno if it's because I'm not a native English speaker, but my intuition about the words unicorn and mermaid doesn't agree (whereas it does agree e.g. with Gettier about the precise meaning of knowledge, and most other similar problems about precise meanings of words).

I think this depends a lot on your exposure to centaur and unicorn myths. Both creatures were imagined in Greece; the centaur was just a mashup of man and horse, and the unicorn was just a kind of horned donkey found in faraway places. Thus, if you slapped a horn on some donkeys (or just found an oryx) you'd have a Greek unicorn.

But in medieval Europe, the unicorn became a symbol of purity, able to cure diseases and drawn to virgins. Oryxes can't cure diseases and aren't drawn to (human) virgins, which to a large extent is the point of a unicorn (to someone who adopts the medieval European imagination of unicorns).

Yeah, that must be the reason. I'm not familiar with mediaeval myths about unicorns, so it means pretty much “a horse with a horn” (but I wouldn't count an oryx as one -- the uni- part means it has to only have one horn, doesn't it :-)), but on the other hand I know about the myth of the mermaids' singing (and Ulysses's strategy to cope with it) so I wouldn't count the top half of a woman glued onto the bottom half of a fish as one.

but on the other hand I know about the myth of the mermaids' singing (and Ulysses's strategy to cope with it

A nitpick: The Odyssey had sirens singing, not mermaids -- and those were half-bird women, not half-fish women. See how they were depicted in ancient times

In Spanish (and presumably also in whichever language is army's native tongue, if it is not Spanish) the word 'sirena' is used for both siren and mermaid, hence the confusion.

Interestingly, mermaid myths may have been deliberate hoaxes, which makes the question of a "real" mermaid even muddier.

I'm not sure how Ctesias or Aristotle would react to seeing an oryx- they might decide it's a new duoceros different from monoceri or they might say "oops, I guess we only saw depictions of monoceri in profile, they actually have two horns."

I am a native English speaker, and I don't agree with the quoted passage either.

My point was that vampires were by definition not real

So according to you, a mosquito that isn't real is a vampire?

His point is that: P(not real | vampire) ~= 1, which is not the same as: "vampire = not real". It's an if-then relationship, not a logical equivalency.

I understand that Phil was not suggesting that all non-real things are vampires. That's why my example was a mosquito that isn't real, rather than, say, a Toyota that isn't real.

But there's nothing particularly special about a mosquito. It's still an incorrect application of modus tollens. We have: If something is a vampire, then it is not real. From this, we can infer (from modus tollens) that if something is real, then it is not a vampire. Thus, if a certain mosquito is real, it is not a vampire. However, there is nothing here that justifies the belief that if a certain mosquito is imaginary, then it is a vampire.

What's special about a mosquito is that it drinks blood.

Phil originally said this:

My point was that vampires were by definition not real - or at least, not understandable - because any time we found something real and understandable that met the definition of a vampire, we would change the definition to exclude it.

Note Phil's use of the word "because" here. Phil is claiming that if vampires weren't unreal-by-definition, then the audience would not have changed their definition whenever provided with a real example of a vampire as defined. It follows that the original definition would have been acceptable had it been augmented with the "not-real" requirement, and so this is the claim I was responding to with the unreal mosquito example.

How about: Vampires are humanoids that can sustain themselves only by drinking blood? That excludes blood-drinking when done occasionally or as a cultural practice.

If it turned out that there was a rare degenerative illness that prevented sufferers from absorbing nutrition from any source other than blood, would you agree that sufferers of that illness were vampires?

Ack. Okay, I guess I have no choice but to add yet another qualifier. :-)

How about: Vampires are very long-lived humanoids that derive their longevity from drinking blood. I can't think of a mundane example that fits that description. Which I suppose was Phil's original point: the only useful definition of "vampire" is one which excludes everything that could plausibly exist.

What about a human with altered biochemistry, such that they could synthesize all needed biological materials from compounds found in blood? Is that a vampire?

Fine. Humans that are incapable of metabolizing anything other than hemoglobin. Does that count?

I'd call them a vampire, but it'd be partly in jest. DSimon's below would give me even less pause, and with a fuller list it seems to become entirely uncontroversial.

My point was that vampires were by definition not real

Actually...

Okay, so here's a dryad. You cut her open, and see white stuff. You take a sample, put it under a microscope, and still see white stuff. You use a scanning tunneling microscope, and still see white stuff. You build an AI and tell it to analyze the sample. The AI converts galaxies into computronium and microscopium, conducts every experiment it can think of, and after a trillion years reports: "The dryad is made of white stuff, and that's all I know. Screw this runaround, what's for dinner?"

But using an outside view of sorts (observed behavior), you can still predict what the dryad will do next. Just like with quarks and with Occam's razor and with prime numbers. And things you haven't reduced yet, but think you can, like people or the LHC.

So, what would you call this dryad?

If you look at it in an STM, you aren't going to be able to see white stuff, because that isn't sensitive to color. But since you were able to image it at all instead of crashing your tip, you can also tell that dryad insides are electrically conductive. We should be able to determine the resistivity of dryad, as a function of gate voltage, impurity density, magnetic field, etc.

No matter what the result is, we now know more about dryad stuff.

So I'd suggest that they be insulating instead, as that closes off all those transport experiments.

If it's causally connected to the physical world, we can test exactly what force(s) it gives out upon other things. We can test how it reflects photons, and all sorts of other things. It would, in the end, have all the physical qualities we attribute to things in this universe, and then it would no longer be mysterious. If it affects us, we can measure that effect.

As to your question, what would I call it?

I'd probably call it a 'dryad'.

Well, it's effects might not be mysterious, but it's nature would be.

"My thesis is that non-reductionism is a confusion; and once you realize that an idea is a confusion, it becomes a tad difficult to envision what the universe would look like if the confusion were true."

I still seem to be able to envision what things would look like if a form of Cartesian dualism were true. Our ordinary laws of physics would govern all matter except one or more places deep in the brain, where the laws of physics would be violated where the soul is "pulling the strings" of the body, as it were. These deviations from physics would not happen unlawfully, but rather would be governed by special, complicated laws of psychology, rather than physics. In principle, this should be testable.

Unlawfulness and nonreductionism are distinct concepts; I can see how the former is incoherent, but the latter still seems logically possible, if false.

I personally can't imagine anything fundamentally complicated. I guess I could imagine tho that something might be a black box with complicated behavior, i.e. something complicated but with no parts that could be analyzed separately (because we can't open the box for whatever reason). But if this something was lawful, we could still analyze the various components of the laws that governed its behavior, e.g. "hmmm ... when we isolate the influence of x, the measurement of the output of the black box seems to correspond roughly to an exponential function of the measurement of x ...".

I don't think lawful and reducible are entirely (or even a little) independent. Really, I'm struggling to think of an example where 'lawful' doesn't mean 'reducible'.

How is dualism necessarily nonreductive? Materialism says everything is reducible to fundamental interacting physical components, whereas dualism says everything is reducible to fundamental interacting physical and mental/spiritual components.

Phil: Vampires ARE real. Both humans and animals can become vampires after being bitten by another vampire (very often a bat or racoon). After being bitten, they will go crazy and attempt to bite others. They also are unable to cross running water.

The virus has been discovered, and a vaccine exists.

http://en.wikipedia.org/wiki/Rabies

Yeah, I know, those aren't "real" vampires, even though that is very likely the source of the vampire mythology.

Eliezer, I think I agree with most of what you say in this post, but unless I misunderstand what you mean by "Bayesian confirmation," I think you're wrong about this bit:

If the "boring view" of reality is correct, then you can never predict anything irreducible because you are reducible. You can never get Bayesian confirmation for a hypothesis of irreducibility, because any prediction you can make is, therefore, something that could also be predicted by a reducible thing, namely your brain.

I think that while you can in this case never devise an empirical test whose outcome could logically prove irreducibility, there is no clear reason to believe that you cannot devise a test whose counterfactual outcome in an irreducible world would make irreducibility subjectively much more probable (given an Occamian prior).

Without getting into reducibility/irreducibility, consider the scenario that the physical universe makes it possible to build a hypercomputer -- that performs operations on arbitrary real numbers, for example -- but that our brains do not actually make use of this: they can be simulated perfectly well by an ordinary Turing machine, thank you very much. If this scenario were true, would it follow that we cannot possibly obtain "Bayesian confirmation" of its truth? I don't think that is the case: Of course, it is true that any empirical test our brains could devise in this scenario could also be passed by a Turing machine that simulated our brains to decide what its answer should be. In fact, every test "does the universe do X if we do Y at time T" we may devise to test whether the universe allows for infinite computations can be met by a Turing machine universe whose code simply includes the instruction to do X at time T. But, such a Turing machine may be complex enough that we start taking "the universe allows for hypercomputation" to be the simpler (and thus, more probable) alternative -- unless we are willing to completely exclude that possibility a priori, which I'm not willing to do and I expect you aren't, either.

Thus, I think that either your argument doesn't support your conclusion, or I don't understand your argument yet :-)

I would ask the same question as Nominull and Tiiba: Why is a fundamentally mental thing different from a fundamentally physical thing like quarks? If we discovered a spirit in a tree that wasn't composed of quarks and leptons, is there a reason we couldn't take that spirit to be a new fundamental particle that behaves in such-and-such a way, just as a down quark is a fundamental particle that behaves in such-and-such a way?

Eliezer: If, on the other hand, a supernatural hypothesis turns out to be true, then presumably you will also discover that it is not inconceivable.

Right. So apart from Occam's razor, what's the reason for excluding things that aren't quarks and leptons from your set of fundamental particles?

Of course water flows downhill because it wants to be lower. It just is not in its nature to be able to want anything else, which distinguishes it from more flexible want-systems like ourselves.

As to the supernatural, I suggest a useful analogy is mathematical objects, like 5, pi, the complex plane, or the Pythagorean theorem. These objects are not physical; they are not made of quarks nor reducible to them, even though any concrete instantiation of them (or instantiation of a thought about them) must involve some physical process; they are non-natural even though they pervade nature. Nobody here would deny the right of mathematicians to be pragmatic Platonists who treat mathematical objects as real things that they can think about and perform mental manipulations on. By analogy, I would at least consider the possibility that theologians have a similar right to make statements about their non-physical, non-natural object of study.

Pure theology is relatively harmless. It's when they start doing applied theology that I wish they would get someone competent to check their calculations.

Funny that you use mathematics as an analogy to something being argued as irreducible, as mathematics is all reducible to fundamentally simple components. And one could even argue that mathematics is 'reducible' to simple physical systems; it's not like you're claiming that every other non-ontologically-fundamental concept or category is Platonically supernatural. What makes the patterns of mathematics special?

Mathematics doesn't escape the Munchausen Trilemma...how do you justify your axioms?

Mathematics, the thing that humans do, completely side-steps the trilemma. There's no need to justify any particular axiom, qua mathematics, because one can investigate the system(s) implied by any set of axioms.

But practically, e.g. when trying to justify the use of mathematics to describe the world or some part thereof, one must accept some axioms to even be able to 'play the game'. Radical skepticism, consistently held, is impractical, e.g. if you can't convince yourself that you and I are communicating then how do you convince yourself that there's a Munchausen Trilemma to be solved (or dissolved), let alone anything else about which to reason?

Mathematics, the thing that humans do, completely side-steps the trilemma. There's no need to justify any particular axiom, qua mathematics, because one can investigate the system(s) implied by any set of axioms.

There's a need to justify axioms if you are going to regard your theorems as true. Game-playing formalism amounts to that, but it is not "mathematics" per se, it is a rather radical take on mathematics.

But practically, e.g. when trying to justify the use of mathematics to describe the world or some part thereof, one must accept some axioms to even be able to 'play the game'.

Which then gets back to the trilemma.

Radical skepticism, consistently held, is impractical, e.g. if you can't convince yourself that you and I are communicating then how do you convince yourself that there's a Munchausen Trilemma to be solved (or dissolved), let alone anything else about which to reason?

Even if I have reason to reject radical scepticism, that doesn't mean I have a solution to the Trilemma.

There's a need to justify axioms if you are going to regard your theorems as true. Game-playing formalism amounts to that, but it is not "mathematics" per se, it is a rather radical take on mathematics.

I just don't feel that this a real practical problem to be solved – I don't have any relevant intuitions about why it would be.

In particular, it doesn't seem like the many interesting results relating to the axiom of choice (AC) – or even more specifically results pertaining to what can or cannot be proved assuming the axiom is true, or not so assuming – are "game-playing formalism". It just doesn't seem to me like it's a particularly useful notion that we must decide, once and for all, whether AC is true or not.

What do you or would you, personally, mean by believing that Euclidean geometry is not true? To me it seems like it's true by default, i.e. 'it' is just all the things implied by its axioms. Whether it's a useful theory with respect to understanding the universe we inhabit is a separate question (and it certainly seems to be the case to me that it is). What then is left by wondering still whether it's 'true'?

But practically, e.g. when trying to justify the use of mathematics to describe the world or some part thereof, one must accept some axioms to even be able to 'play the game'.

Which then gets back to the trilemma.

I don't follow you. If we "must accept some axioms to even be able to 'play the game'" then it seems like, at least practically, the trilemma is solved by accepting the 'axiomatic argument', i.e. "accepted precepts".

particular, it doesn't seem like the many interesting results relating to the axiom of choice (AC) – or even more specifically results pertaining to what can or cannot be proved assuming the axiom is true, or not so assuming – are "game-playing formalism".

I can make no sense of that, because taking something as true only in relation to an axiom whose truth is itself unknown is precisely what game playing formalism means. You seem to simultaneously asserting and denying he same thing.

What do you or would you, personally, mean by believing that Euclidean geometry is not true?

GPF mean Euclidean isn't true in any sense other than being a valid deduction from arbitrary premises,..for instance, that it isn't true in the sense of corresponding to the territory, and that it isn't true in the sense of being derived from non-arbitrary premises. As it happens, our best physics tells us that the universe does not have Euclidean geometry, so truth by correspondence is out, and we also know that the Euclidean axioms are not the only self -consistent axiom set, so the axioms of Euclidean geometry look arbitrary. All that being the case, Euclidean geometry is either false simpliciter, or true only in the diluted sense allowed by GPF.

It' is just all the things implied by its axioms.

Again, you seem to be agreeing with the substance of GPF while rejecting the label.

Whether it's a useful theory with respect to understanding the universe we inhabit is a separate question (and it certainly seems to be the case to me that it is). What then is left by wondering still whether it's 'true'?

If it were true in a full-strength sense, that would be an example of something that has evaded the Muchausen Trilemma.

then it seems like, at least practically, the trilemma is solved by accepting the 'axiomatic argument', i.e. "accepted precepts".

I think you are missing something important. The Trilemma doesn't just mean you have to choose between three methods of justification, it means you have to choose between three bad methods. If you can only say that something is true relative to some arbitrary axioms, then you can't say it is true in an absolute sense.

our best physics tells us that the universe does not have Euclidean geometry

How do you know that? How could I know that? Is either of our knowledge of this 'true'?

I don't understand how we're having this conversation if we don't both consider some things true and even agree that some of the same things are true.

Again, you seem to be agreeing with the substance of GPF while rejecting the label.

Yeah, that seems to be the case. Is the label not pejorative? Is it not intended to exclude the substance to which it refers by mockery?

If it were true in a full-strength sense, that would be an example of something that has evaded the Muchausen Trilemma.

I don't know why this would be interesting in and of itself. Assuming anything could be "true in a full-strength sense" and something was 'true in that sense', what would that mean?

I think you are missing something important. The Trilemma doesn't just mean you have to choose between three methods of justification, it means you have to choose between three bad methods.

It seems like you're trying to push some kind of imagined reductio ad absurdum but I refuse to play your game! I pronounce the Trilemma dissolved by virtue of the 'axiomatic argument' not being a bad method for justifying truth, actual mundane truth not 'absolute truth'.

If you can only say that something is true relative to some arbitrary axioms, then you can't say it is true in an absolute sense.

I agree and I freely admit that nothing is true in an absolute sense. I don't even know what that would mean. What could possibly be true – and expressible in a language made and used by humans – "in an absolute sense"?

Could you explain to me what the difference would be between something that is merely 'mundanely true' and something that is 'absolutely true'?

What would be different about the world if something was 'absolutely true'? What would be different if we knew that something was 'absolutely true'? And even if something was absolutely true how could we ever trust that we could know it was 'absolutely true'?

I don't understand how we're having this conversation if we don't both consider some things true and even agree that some of the same things are true.

I am not asserting that nothing is true.

Is the label not pejorative? Is it not intended to exclude the substance to which it refers by mockery?

No and no.

I don't know why this would be interesting in and of itself. Assuming anything could be "true in a full-strength sense" and something was 'true in that sense', what would that mean?

Prinicpally that its truth doesn't depend on arbitrary assumptions.

I pronounce the Trilemma dissolved by virtue of the 'axiomatic argument' not being a bad method for justifying truth, actual mundane truth not 'absolute truth'.

Most people think of mundane truth as absolute truth. The relative truth offered by GPF is a rather idiosyncratic taste.

I agree and I freely admit that nothing is true in an absolute sense. I don't even know what that would mean. What could possibly be true – and expressible in a language made and used by humans – "in an absolute sense"?

It's meaning is a straightforward reversal of "in a relative sense". If the one is comprehensible, so is the other.

Of course, you might be using "I can't see what absolute truth would mean" to mean "I can't see how absolute truth can be obtained"....

Could you explain to me what the difference would be between something that is merely 'mundanely true' and something that is 'absolutely true'?

I never used the phrase "mundanely true", so I don't have to explain it. As I have explained, the popular notion of truth is absolute, not relative, so the Munchausen Trilemma, if irresolvable, has the momentous implication that people can't have the only kind of truth they believe in.

Is the label not pejorative? Is it not intended to exclude the substance to which it refers by mockery?

No and no.

That seems unlikely. Describing something as 'game-playing' seems to be clearly implying that it's not serious, and therefore unworthy of serious consideration. How do you know it's not pejorative? Or were you merely asserting that you are not using it pejoratively?

I don't know why this would be interesting in and of itself. Assuming anything could be "true in a full-strength sense" and something was 'true in that sense', what would that mean?

Prinicpally that its truth doesn't depend on arbitrary assumptions.

I'm still confused. If a truth doesn't depend on "arbitrary assumptions" what makes it different than an "arbitrary assumption"? If you're familiar with mathematics, what would a sketch of a 'constructive proof' of an absolute truth look or seem like?

Presumably, something "true in a full-strength sense" would not depend on "arbitrary assumptions". If it depends on no other truths it seems equivalent to an axiom. Do you disagree? If you do disagree, can you help me understand how a truth like this could exist? Could you describe anything about such a truth that would be different than other truths?

I pronounce the Trilemma dissolved by virtue of the 'axiomatic argument' not being a bad method for justifying truth, actual mundane truth not 'absolute truth'.

Most people think of mundane truth as absolute truth. The relative truth offered by GPF is a rather idiosyncratic taste.

Let's ignore most people. I don't think of mundane truth as absolute truth. If you're not arguing that they're the same, what are you arguing?

I agree and I freely admit that nothing is true in an absolute sense. I don't even know what that would mean. What could possibly be true – and expressible in a language made and used by humans – "in an absolute sense"?

It's meaning is a straightforward reversal of "in a relative sense". If the one is comprehensible, so is the other.

So there's nothing else distinctive about absolute truth other than it 'not being relative'? That seems pretty uninteresting.

Of course, you might be using "I can't see what absolute truth would mean" to mean "I can't see how absolute truth can be obtained"....

Of course you might have written:

Mathematics doesn't escape the Munchausen Trilemma...how do you justify your axioms?

but you didn't actually mean anything by it. You haven't committed to claiming that mathematics is false; just that they're not 'absolutely true'. You haven't provided any means of distinguishing 'absolute truth' from any other kind other than claiming that the former is the complement of the latter among the set of all truths (or something similar).

You haven't offered any reason to care about 'absolute truth' or any ideas about the benefits acquiring such truths would render; nor any constructive, even-minutely-specific details about how one would acquire them.

I never used the phrase "mundanely true". As I have explained, the popular notion of truth is absolute, not relative, so the Munchausen Trilemma, if irresolvable, has the momentous implication that people can't have the only kind of truth they believe in.

I'm not arguing for any popular notion of truth. I claim truth is not absolute and cannot be.

Is there anything left to discuss?

Note that my original comment to which you replied was about mathematics being reducible, not absolutely true (or otherwise).

That seems unlikely. Describing something as 'game-playing' seems to be clearly implying that it's not serious, and therefore unworthy of serious consideration. How do you know it's not pejorative? Or were you merely asserting that you are not using it pejoratively?

Principally the latter, I suppose, although I don;t think it is particularly perjoritive in any case.

Prinicpally that its truth doesn't depend on arbitrary assumptions.

I'm still confused. If a truth doesn't depend on "arbitrary assumptions" what makes it different than an "arbitrary assumption"? If you're familiar with mathematics, what would a sketch of a 'constructive proof' of an absolute truth look or seem like?

There are any number of areas of knowledge where the axioms aren't at all obvious.

Presumably, something "true in a full-strength sense" would not depend on "arbitrary assumptions". If it depends on no other truths it seems equivalent to an axiom.

Consider an observation. Is that an axiom?

So there's nothing else distinctive about absolute truth other than it 'not being relative'? That seems pretty uninteresting.

And there's nothing distinctive about God's existence other than it's being the opposite of God's non-existence. You seem to be associating momentousness with complexity.

You haven't provided any means of distinguishing 'absolute truth' from any other kind other than claiming that the former is the complement of the latter among the set of all truths (or something similar).

The means of distinguishing them is just the kind of argument we are having now. Of course, that is not particularly algorithmic. If you are running on the implicit assumption that nothing is meaningful unless it has very precise, algorithmic truth conditions, then that could do with being made explicit.

You haven't offered any reason to care about 'absolute truth'

I have in fact explained why the non existence of absolute truth would turn the world upside down for billions of people.

Consider use of arbitrary axiom in arguments with real-world implications:

Axiom1: You owe me a whole number sum greater than $99. Axiom2: You owe me a whole number sum less than $101. Conclusion: You owe me $100.

So.. do you owe me that money? Arbitrary axioms are relatively safe in mathematics, because it is abstract..they are pretty disastrous when applied to the real world.

I'm not arguing for any popular notion of truth. I claim truth is not absolute and cannot be.

Is there anything left to discuss?

Yes: whether you are correct.

Mathematics does not "compeltely" sidestep the Munchausen Trillema, because completely sidestrepping it would not involve a compromise nature of truth!

Prinicpally that its truth doesn't depend on arbitrary assumptions.

I'm still confused. If a truth doesn't depend on "arbitrary assumptions" what makes it different than an "arbitrary assumption"? If you're familiar with mathematics, what would a sketch of a 'constructive proof' of an absolute truth look or seem like?

There are any number of areas of knowledge where the axioms aren't at all obvious.

It's not clear to me how your reply is relevant. But by your own criteria, in what sense do these areas consist of 'knowledge' if there are no obvious axioms? In what sense is something known if it's not true? Do you mean knowledge in a sense that I would accept?

Regardless of the obviousness of axioms for a particular area of knowledge – doesn't an area of knowledge accept – at least implicitly – a number of axioms? It sure seems to me that, in practice, every area of knowledge simply accepts many claims as axioms because it's impossible to reason at all without assuming something. For example, every area assumes that people exist, that the relevant object(s) of study exist, that people can gather evidence somehow of the objects of study, that the universe is not arbitrary and capricious 'magic', etc.

And there's nothing distinctive about God's existence other than it's being the opposite of God's non-existence. You seem to be associating momentousness with complexity.

That's not true (ha)! Certainly God's existence is incredibly distinctive in so far that God has definite attributes and there is some correlation between those attributes and the universe we can observe. If there is no such evidence it's not clear in what sense God 'exists'.

What I've yet to glean from your comments is how 'absolute truth' is any different than 'green sound'. They're both short phrases but neither seems to refer to anything.

You haven't provided any means of distinguishing 'absolute truth' from any other kind other than claiming that the former is the complement of the latter among the set of all truths (or something similar).

The means of distinguishing them is just the kind of argument we are having now. Of course, that is not particularly algorithmic. If you are running on the implicit assumption that nothing is meaningful unless it has very precise, algorithmic truth conditions, then that could do with being made explicit.

The argument in which I've been participating is whether 'absolute truth' is coherent in principle. A means of distinguishing it from some other potential kind of 'truth' would certainly help me better understand what you seem to be trying to communicate.

The means of distinguishing them is just the kind of argument we are having now. Of course, that is not particularly algorithmic.

What's not "particularly algorithmic"? I don't think you've provided a means of distinguishing between absolute truth and other truths. Did I miss it or miss them? I'd be curious if you could offer any potential means in any form.

You haven't offered any reason to care about 'absolute truth'

I have in fact explained why the non existence of absolute truth would turn the world upside down for billions of people.

You did? You simply asserted that most people conflate 'truth' and 'absolute truth' but I disagree. For one reason, I can't distinguish between people believing something to be an 'absolute truth' and believing something to be an 'axiom'.

But let's assume that most people believe things to be 'absolutely true' and yet, somehow, someone convinces them of the non-existence of absolute truth. What exactly causes the 'world to be turned upside down' for these people? That, because they think all truth is 'absolute truth' and that they're now convinced that the latter doesn't exist that therefore nothing is true? If they think nothing is true would that also include the belief or claim that 'absolute truth does not exist'?

Consider use of arbitrary axiom in arguments with real-world implications:

Axiom1: You owe me a whole number sum greater than $99. Axiom2: You owe me a whole number sum less than $101. Conclusion: You owe me $100.

So.. do you owe me that money? Arbitrary axioms are relatively safe in mathematics, because it is abstract..they are pretty disastrous when applied to the real world.

Your entire argument seems like an attempt at a 'sophisticated' justification of radical skepticism. So I'm not sure how I can possibly accept or decline either of those axioms. On what grounds would I do so or not do so?

What you seem to be trying to sidestep tho is a number of claims or beliefs that are required for the scenario you described above to even be sensible:

  1. There is a thing 'you'.
  2. There is a thing 'me'.
  3. That there are things 'the natural numbers'.
  4. There are things 'dollars' quantified using 'natural numbers'.
  5. That the things 'you' and 'me' could possibly be related such that one of us 'owes' the other some number of 'dollars'. x. ...

Those claims, those beliefs, are what seem like required axioms. Because without assuming they're true it's not clear in what sense one can believe anything, let alone engage in written communication about something.

It's pretty clear you're acting as-if you believe I exist and that I can engage in an argument or discussion with you. It's pretty clear that there is a 'you', tho the details of your person are largely unknown to me, e.g. whether you're really a number of distinct people.

There is no "ideal philosophy student of perfect emptiness" on which 'absolute truth' could possibly be bestowed. By the way, that post to which I just linked covers all the reasons why the idea of 'absolute truth' is not even wrong.

You and I were both bootstrapped as minds with already existing 'axioms', tho really none of them are incapable of being revised or replaced.

Mathematics does not "compeltely" sidestep the Munchausen Trillema, because completely sidestrepping it would not involve a compromise nature of truth!

Okay, everything completely sidesteps the Münchhausen trilemma because it's not actually a trilemma, because there is no absolute perfect truth of which anyone is capable of knowing.

Or, nothing involves a "compromise nature of truth" – because there's only one 'truth', it's built on evidence, and it's all bootstrapped by evolution and history.

From the end of the linked post, A Priori:

Perhaps you cannot argue anything to a hypothetical debater who has not accepted Occam's Razor, just as you cannot argue anything to a rock. A mind needs a certain amount of dynamic structure to be an argument-acceptor. If a mind doesn't implement Modus Ponens, it can accept "A" and "A->B" all day long without ever producing "B". How do you justify Modus Ponens to a mind that hasn't accepted it? How do you argue a rock into becoming a mind?

Brains evolved from non-brainy matter by natural selection; they were not justified into existence by arguing with an ideal philosophy student of perfect emptiness. This does not make our judgments meaningless. A brain-engine can work correctly, producing accurate beliefs, even if it was merely built - by human hands or cumulative stochastic selection pressures - rather than argued into existence. But to be satisfied by this answer, one must see rationality in terms of engines, rather than arguments.

The Münchhausen trilemma has been around for awhile and yet truth is just as true as ever. No one is bothered by it in practice. It's an empty argument.

It's not clear to me how your reply is relevant. But by your own criteria, in what sense do these areas consist of 'knowledge' if there are no obvious axioms?

In the sense that they are taught in classrooms, cited in encyclopedias and so on. Take empirical knowledge. It may be based on vague intuitions, but it isn't based on formal axioms.

Do you mean knowledge in a sense that I would accept?

I have no idea what you would accept.

It sure seems to me that, in practice, every area of knowledge simply accepts many claims as axioms because it's impossible to reason at all without assuming something. For example, every area assumes that people exist, that the relevant object(s) of study exist, that people can gather evidence somehow of the objects of study, that the universe is not arbitrary and capricious 'magic', etc.

I have been drawing a distinction between necessary presuppositions ("intuitions") and arbitrary premises ("axioms). The wholesale embrace of derivation from arbitrary axioms as fully-fledged truth leads to the undesirable outcome of an epistemological explosion..every proposition becomes proveable and disproveable.

Trying to manage without even the most basic intuition is desirable, but, as far as we can tell, impossible.

However, the ineradicability of some intuitions doesn't make the wholesale embrace of arbitrary axioms a good idea! If we cannot manage without intuitions, we can avoid the worst of the problems by minimising their use, particularly in real-world contexts, but that is damage containment, not a full solution,

What I've yet to glean from your comments is how 'absolute truth' is any different than 'green sound'. They're both short phrases but neither seems to refer to anything.

If "depends on axioms" has a meaning, "does not depend on axioms" has a meaning. Whether truth indpendent of axioms is obtainable is another question.

hat exactly causes the 'world to be turned upside down' for these people? That, because they think all truth is 'absolute truth' and that they're now convinced that the latter doesn't exist that therefore nothing is true? If they think nothing is true would that also include the belief or claim that 'absolute truth does not exist'?

Only if the law of the excluded middle remain robustly true, which it doesn't...

So.. do you owe me that money? Arbitrary axioms are relatively safe in mathematics, because it is abstract..they are pretty disastrous when applied to the real world.

Your entire argument seems like an attempt at a 'sophisticated' justification of radical skepticism. So I'm not sure how I can possibly accept or decline either of those axioms. On what grounds would I do so or not do so?

The argument is supposed to work as a reductio ad absurdum. You are supposed to disbelieve the conclusion that you owe me money, and therefore reject the assumption that "truths about the real world can be derived from arbitrary axioms".

And notice the amount of work being done by "arbitrary" here.

There is a thing 'you'. There is a thing 'me'. That there are things 'the natural numbers'. There are things 'dollars' quantified using 'natural numbers'. That the things 'you' and 'me' could possibly be related such that one of us 'owes' the other some number of 'dollars'. x. ...

There is some sort of evidence of argument for all of those, so they are neither arbitrary nor axiomatic, strictly speaking.

Mathematics does not "completelly" sidestep the Munchausen Trillema, because completely sidestrepping it would not involve a compromise nature of truth!

Okay, everything completely sidesteps the Münchhausen trilemma because it's not actually a trilemma, because there is no absolute perfect truth of which anyone is capable of knowing.

That amounts to saying that the MT is true because it is false. That there is no absolute truth, no entirely satisfactory means of justification is the conclusion of the MT, so adopting it as a premise is hardly to argue against MT.

You seem to think that in the absence of absolute truth , relative truth is 1) unavoidable and 2) unproblematic.

But 1) doesn't follow, because there is a third option, scepticism.

and 2) doesn't follow, because of epistemological explosion. We always do have background intuitions , and one of them is that the set of true propositions isn't a huge, incoherent , self-contradictory morass.

We can avoid the worst of (2) by minimising the use of intuition, but because that is not a full solution, we also need to adopt a degree of scepticism in recognition of the fact.

Or, nothing involves a "compromise nature of truth" – because there's only one 'truth', it's built on evidence, and it's all bootstrapped by evolution and history.

if the arbitrary axioms are handed to us by evolution, they are still arbitrary in the ways that matter. So your rightly scare quoted 'truth' isn't known to be true, and the MT still applies.

The Münchhausen trilemma has been around for awhile and yet truth is just as true as ever.

How do you know?

What I've yet to glean from your comments is how 'absolute truth' is any different than 'green sound'. They're both short phrases but neither seems to refer to anything.

It's kind of a side point, but there actually is such a thing as green noise (there's actually four different definitions...)

Definitely a side point, but thanks for the info anyways!

The investigation of the systems implied by a set of axioms also requires some assumptions. For example, one must assume that any axiom implies itself, i.e. P -> P. Once this axiom is accepted, there are a great number of logical axioms which are equally plausible.

This is why I claim that atheism is an established scientific result. One of the strongest lines of evidence is, indeed, that we have successfully reduced minds and shown the notion of an irreducible mind to be incoherent. Mind as an irreducible simple is basic to all monotheistic religions. Demonstrating something once thought coherent to be incoherent is, of course, one of the strongest lines of evidence in science. Other avenues through which atheism has been established by science include conservation in physics, chemistry and biology (which led directly to materialism), evolution, and the development of plausible sociological accounts of religion. I would argue that atheism is as well established as Plate Tectonics and Natural Selection. What I think is telling is that most contemporary approaches to religious apologetics implicitly recognize that science has established atheism.

The theist has three avenues of response. The first is to attack specific parts of science. This is what Fundamentalist Christians do. The second, by far the most popular, is to attack the very possibility of scientific knowledge. This is what nearly all "liberal" religious believers who claim there is no conflict between science and religion do. They generally adopt a skeptical epistemology, holding that no knowledge claim can be true, or instrumentalism about science, holding that scientific claims are nonfactual, or a quasi-Kantian constructivist metaphysics wherein "true" reality is forever out of reach. The weird thing is that this position, which essentially rejects all of science, is considered more "sophisticated" and acceptable than the Fundamentalist position which rejects only select parts of science but remains realist about the rest. The third approach is to adopt some sort of nonfactualism about religious claims; essentially to hold that your religious practice is merely tradition. I think this nearly exhausts contemporary positions on religious apologetics and is therefore evidence that people implicitly accept that science has established atheism.

If we have succefully reduced minds, that only shows that the claim that minds are irreducible is false, not that it is incoherent,

Ennui: "In that special Cartesian theater, I can picture an even smaller Homunculus pulling the strings of the larger."

But what if the homunculus were ontologically fundamental?--of course the notion is silly and of course it's false, but I'm not yet convinced that it's literally nonsense on the order of square circles or A-and-not-A. It could be that I just need some intuition-reshaping, but in the meantime I can do nothing else but call it as I see it.

Substance dualism doesn't even require that homunculi be fundamental. It only requires that they be built from mind-stuff. They can be composite agents in the sense of co-operative game theory. Maybe that explains why humans are not perfectly rational. We are controlled by a committee.

Constant: with dogs, you can point to examples and say "these animals, and animals closely related to these are dogs".

...whereas with vampires, you're stuck pointing to a collection of fictional representations. This restricts certain information-gathering techniques (you can't put a vampire under a microscope; at best, you can use a fictional account of a vampire under a microscope) but shouldn't make the exercise impossible. I'm pretty sure we could convey 'stop sign' without ever letting you observe a real-life stop sign.

If the "boring view" of reality is correct, then you can never predict anything irreducible because you are reducible. You can never get Bayesian confirmation for a hypothesis of irreducibility, because any prediction you can make is, therefore, something that could also be predicted by a reducible thing, namely your brain.

Some boxes you really can't think outside. If our universe really is Turing computable, we will never be able to concretely envision anything that isn't Turing-computable—no matter how many levels of halting oracle hierarchy our mathematicians can talk about, we won't be able to predict what a halting oracle would actually say, in such fashion as to experimentally discriminate it from merely computable reasoning.

I don't quite understand this one. How does "you are reducible" imply "you cannot conceive anything nonreducible"? Human beings with their merely Turing-complete brains can understand the concept of a non-Turing-computable problems. If our universe turns out to be more than Turing computable, and aliens give us a box that can map an integer to an integer by a non-computable function together with a verbal description of the function (say, "N -> busy-beaver(N)"), we will be able to use it, and understand what it does and why it is useful. Even though we will not be able to predict the exact outputs without a similar box, we could conceive what would the output look like ("like an integer bigger than X and smaller than Y"). Correspondingly, I see no impossibility in that a reducible brain can imagine what a non-reducible universe would look like.

Say, suppose there is a universe made of three types of things: ghosts, transistors and billiard balls. Transistors and billiard balls can form structures that compute functions up to primitive recursive. Billiard balls can interact with ghosts and transistors, acting as an interface between two. Ghosts can directly interact only with billiard balls. Every ghost observes the state of billiard balls around itself every five seconds and outputs one of actions: haunt, spook or wail, that affect the billiard balls in some way. The computation performed by a ghost is Turing-complete, but not primitive recursive. Thus, ghosts can never be reduced to transistors and billiard balls. Creatures made of transistors can observe billiard balls and infer the existence of ghosts. They will obviously not be able to form a complete model of a ghost, but they could make statistical observations about them. They could form primitive recursive statements, such as "a ghost spooks 50% of the time regardless of billiard balls around, except if it was surrounded by four balls in pyramidal pattern 5 seconds ago, in which case it always haunts". These statements will not describe the entire behavior of a ghost, but they will be conceivable, imaginable and detectable by transistor-creatures. And it, I suppose, is a probable thought that can occur to a transistor-creature - "what if ghosts are not computable?" (in their definition of computability that is merely primitive recursive).

In the same way, I see no trouble in visualizing a world which is just like ours, but contains a non-reducible-to-quarks, non-computable (by my definition of computability that is merely Turing computable) ghost that reads the state of quarks and produces a behavior that is outside of the box I'm thinking in. It will be my problem, not Universe's.

There's a difference between an existence proof and a constructive proof. We can talk about existence proofs for, "Here's what happens when we hook a magical Halting Oracle to a Turing Machine and run certain programs." We do not have any constructive proof of how a Halting Oracle would behave.

Just because you can say, "Imagine we had a thing with these properties" doesn't mean you know how to build such a thing.

I have to wonder if your characterization of people who deny reductionism is really correct. I agree most of them are probably confused and do not have a coherent model in the first place - certainly actual non-reductionism is a confusion - but I'm not certain all of them are confused in the way you say.

From my experience it seems that the claims of the people who deny "reductionism" could be coherently understood if we assume that they are actually confused about what reductionism actually consists of, and that they are not denying actual reductionism, just one particular version of it that they are imagining the term necessarily refers to.

E.g. if we assume that they are simply saying that in some cases, the irreducible components of the universe are complicated rather than simple, and that the lowest level is something that appears to be "high level", then this is, though almost certainly wrong, at least coherent. It is also technically reductionist, albeit possibly trivially so (worst case: entire universe is a giant lookup table). But they don't think of it as reductionism as it doesn't much resemble what they're used to seeing called by that name.

Indeed I would go so far as to say that the people who deny reductionism are very often the same people who are implicitly making the mistake of greedy reductionism! They fail to think in terms of interactions of components, of actual systems, and so make the mistake of inferring angry atoms. They do reduce things, it's just that they reduce everything to supernatural things that can only interact via some sort of superposition principle. This pretty much fails at predicting anything, but it is at least coherent.

I don't know, does this make sense?

Mm. It makes sense, but I don't think it's on-point.

Up to a point, I agree with you. The Bohr model of the atom posits a lowest-level description that appears to us now to be "high-level", as you say, but it would not be fair to dismiss Bohr as a denier of reductionism on that basis. Similarly, if 22nd-century physics demonstrates that our current ontology is similarly confused, and there is a yet-more-parsimonious explanation that is consistent with observed data, it would not be fair to claim we deny reductionism.

It's unfair precisely because it elides the difference between (on the one hand) not being able to analyze something in terms of its component parts and (on the other) rejecting in principle any such analysis.

EY seems to be talking here about people who do the latter... who would deny that anything explainable could be their God, whatever surface properties it turned out to have. You seem to be talking about both groups at once.

To put this a different way... suppose Alice, Bob, and Cindy all worship a dryad, who is either Tiiba's dryad or an analog made of quarks, and a scientist comes along to determine which it is. Alice insists that studying the dryad's composition isn't possible/permitted. Bob confidently predicts that the dryad will all be whitestuff. Cindy shrugs and doesn't care; she makes the choice to worship based on surface-level considerations that don't depend on whether it's quarks or whitestuff.

Alice and Bob both make supernatural claims. Cindy isn't making a supernatural claim at all, by this post's definitions.

You argue that Bob is just claiming that some irreducible components are complicated, and the dryad happens to be one of them, and that this is perfectly compatible with reductionism (albeit perhaps trivially so)... even if Bob doesn't call himself a reductionist.

And that's true enough, as far as it goes. Bob is also admitting that his supernatural claim is testable and falsifiable by scientific research.

Meanwhile, Alice claims "separate magisteria."

As far as I can tell, the argument of EY's post relates exclusively to Alice.

I remember, when first reading this article, that it was really convincing and compelling. I looked it up again because I wanted to be able to make the argument myself, and now I find that I don't understand how you can get from "if the staid conventional normal boring understanding of physics and the brain is correct" to "there's no way in principle that a human being can concretely envision, and derive testable experimental predictions about, an alternate universe in which things are irreducibly mental." That seems like too large a jump for me. Any help?

God is a shapeshifting horror from the outer beyond that constantly adapts its properties to whatever is most convenient given the argument currently being considered.

@poke (i think you posted in the wrong thread) -- if you did a survey, limited to scientists, and asked questions like "is general relativity largely correct?', or 'Does DNA encode genes?', you would get near-100% agreement. If you asked 'is atheism true?', you would get a much lower number. Therefore, whatever opinions or arguments might seem convincing to you personally, atheism is not the strongest modern scientific result.

As ought to be obvious, statements about god are not scientific statements. You will not find peer-reviewed scientific literature proving or disproving the existence of god. God is a topic of endless of fascination on the fringes of science, which include philosophy, blogs like this one and popular books written by scientists, but is largely absent from the literature of actual science, for good reason.

If god is not a natural being, then science does not have the means to say whether it exists or not. It is not even clear what "exists" means for such entities. You can say that it makes no sense to talk about non-natural, non-material entities in any way, but as I pointed out before, we do it all the time for mathematical entities and I assume nobody here has a problem with that.

I find atheist fundamentalists amusing, because they are so certain that they know what "god" means, just like religious fundamentalists. Most sane and intelligent people with religious tendencies (and there are many, although they don't seem to get much press) understand that if "god" means anything, it is a pointer towards something unknown and perhaps unknowable, and arguing about whether it exists in the physical sense is missing the point completely.

Good post. For a question to receive a specific answer, it must be itself specific. "Does God exist?" is not a specific question and can therefore not receive a specific yes/no/dunno answer. "Does Yahweh exist?" on the other hand, is quite specific and requires the equally specific answer of "No."

There are some perfectly well-defined generalizations, for instance "Was our portion of this universe designed in detail by an intelligent mind?"

(Of course, I take the Simulation Hypothesis seriously enough to answer either "Maybe" or "Yes and No", though further well-defined questions do distinguish between that hypothesis and more traditionally theist ones.)

Z. M. Davis: But if you think about the things that the homunculus tends to do, I think you would find yourself needing to move to levels below the homunculus to do it. To give it a coherent set of actions it is likely to take, and not to take, at any given time, you would have to populate it with wants, with likes, with beliefs, with structures for reasoning about beliefs.

I think eventually you would come to an algorithm of which the homunculus would have to be an instantiation, and you would have to assume that that algorithm was represented somewhere.

I just don't see how you can make sensible predictions about ontologically basic complicated things. And I know people will go on about how you can't make predictions about a person with free will, but that's a crock. You expect me to try to coherently answer your post. I expect a cop to arrest me if I drive too fast. More to the point, we don't expect neurologically intact humans to spend three years walking backwards, or talk to puddles, or remove their clothing and sing "I'm a little teapot" in Times Square.

And the same goes for gods, incidentally. Religious folk will say that their gods' ways are ineffable, that they can't be predicted. But they still expect their gods to answer prayers, and forgive sins, and torture people like me for millennia, and they don't expect them to transform mount everest into a roast beef sandwich, or thunder forth nursery rhymes from the heavens.

They have coherent expectations, and for those expectations to make sense you have to open the black box and put things in there. You have to postulate structure, and relationships between parts, and soon you haven't got something ontologically basic anymore.

Eliezer, your characterization of religion is not generally accurate, as evidenced by the fact that not all religious persons posit an irreducibly complex God. As one example, Mormons posit a material God that became God through organizing existing matter according to existing laws.

On the other hand, I wonder, do you attribute irreducible complexity to quarks?