Scientist by training, coder by previous session,philosopher by inclination, musician against public demand.
Team Piepgrass: "Worried that typical commenters at LW care way less than I expected about good epistemic practice. Hoping I’m wrong."
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.
Physicalism, materialism, empiricism, and reductionism are clearly similar ideas, but not identical. Carrier's criterion captures something about a supernatural ontology, but nothing about supernatural epistemology. Surely the central claim of natural epistemology is that you have to look...you can't rely on faith , or clear ideas implanted in our minds by God.
it seems that we have very good grounds for excluding supernatural explanations a priori
But making reductionism aprioristic arguably makes it less scientific...at least, what you gain in scientific ontology, you lose in scientific epistemology.
I mean, what would the universe look like if reductionism were false
We wouldn't have reductive explanations of some apparently high level phenomena ... Which we don't.
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.
Note that there are four possibilities here...
I assume a one level universe, all further details are correct.
I assume a one level universe, some details may be incorrect
I assume a multi level universe, all further details are correct.
I assume a multi level universe, some details may be incorrect.
How do we know that the MPF is actually fallacious, and what does it mean anyway?
If all forms of mind projection projection are wrong, then reductive physicalism is wrong, because quarks, or whatever is ultimately real, should not be mind projected, either.
If no higher level concept should be mind projected, then reducible higher level concepts shouldn't be ...which is not EY's intention.
Well, maybe irreducible high level concepts are the ones that shouldn't be mind projected.
That certainly amounts to disbelieving in non reductionism...but it doesn't have much to do with mind projection. If some examples of mind projection are acceptable , and the unacceptable ones coincide with the ones forbidden by reductivism, then MPF is being used as a Trojan horse for reductionism.
And if reductionism is an obvious truth , it could have stood on its own as apriori truth.
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?
Science isn't 100% observation,it's a mixture of observation and explanation.
A reductionist ontology is a one level universe: the evidence for it is the success of reductive explanation , the ability to explain higher level phenomena entirely in terms of lower level behaviour. And the existence of explanations is aposteriori, without being observational data, in the usual sense. Explanations are abductive,not inductive or deductive.
As before, you should expect to be able to make reductive explanations of all high level phenomena in a one level universe....if you are sufficiently intelligent. It's like the Laplace's Demon illustration of determinism,only "vertical". If you find yourself unable to make reductive explanations of all phenomena, that might be because you lack the intelligence , or because you are in a non reductive multi level universe or because you haven't had enough time...
Either way, it's doubtful and aposteriori, not certain and apriori.
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"
I think I have answered that. I don't need observations to rule it out. Observations-rule it-in, and incoherence-rules-it-out aren't the only options.
People who live in reductionist universes cannot concretely envision non-reductionist universes.
Which is a funny thing to say, since science was non-reductionist till about 100 years ago.
One of the clinching arguments for reductionism.was the Schrödinger equation, which showed that in principle, the whole of chemistry is reducible to physics, while the rise of milecular biology showeds th rreducxibility of Before that, educators would point to the de facto hierarchy of the sciences -- physics, chemistry, biology, psychology, sociology -- as evidence of a multi-layer reality.
Unless the point is about "concretely". What does it mean to concretely envision a reductionist universe? Pehaps it means you imagine all the prima facie layers, and also reductive explanations linking them. But then the non-reductionist universe would require less envisioning, because byit's the same thing without the bridging explanations! Or maybe it means just envisioing huge arrays of quarks. Which you can't do. The reductionist world view , in combination with the limitations of the brain, implies that you pretty much have to use higher level, summarised concepts...and that they are not necessarily wrong.
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.
"Your brain is made of quarks" is aposteriori, not apriori.
Your brain being made of quarks doesn't imply anything about computability. In fact, the computatbolity of the ultimately correct version of quantum physics is an open question.
Incomputability isn't the only thing that implies irreducibility, as @ChronoDas points out.
Non reductionism is conceivable, or there would be no need to argue for reductionism.
Know for certain? I think you have.conceded that some metaphysical claims are less likely than others.
It you place a terminal value on knowing how things really work, then it has a value for you, even if it's basically academic and lacking in instrumental value
Instrumental value doesn't float free of terminal value..it's got to be instrumental for something.
To get a little more into why I think it’s not worth doing metaphysics
Surely you can value whatever you like...or are you saying its not possible to make progress in metaphysics ?
all metaphysical claims must converge to account for our observations.
They must retrodict the same observations -- phenomena -- but that doesn't mean they have to agree on the behind-the-scenes mechanisms .
which means we have no way to distinguish them except by non-observable evidence,
Non observable "evidence" can consist of conditions like simplicity and consistency, which are accessible, even if not to the senses. They are also used in science.
The “physics of cognition” hypothesis is that the relevant quantum dynamics includes a non-Turing-computable quantum-gravitational selection of eigenstates, which in its deepest form manifests as the metamathematical ability to transcend any particular axiom system via conscious insight into the meanings of the axioms.
OK, but that's another unnecessary problem, because you don't have to regard the mind as a (consistent) axiomatic system.
Along with the hard problem, you mention the problem of accounting for knowledge of mathematical truth. Penrose is indeed tackling an aspect of that problem, but with the very specific priority of explaining how mathematical knowledge is possible, given the constraints on knowledge implied by Gödelian theorems.
There's no way of confirming that we have a kind of knowledge that goes beyond "proveable from unfounded axioms" and "seems to work in practice".
Perhaps we aren't as limited as a single formal system, but then we might be using cheap tricks like switching between systems, using intuition, or tolerating inconsistency.
There aren’t many people who have embraced this approach to the challenge of Gödelian limits to physically based thought. The most common approach is to suppose that the human brain simply is genuinely finite in its capabilities and that there are mathematical facts that inherently transcend us.
From the anti realist point of views, If there are facts that transcend everyone, they aren't facts. They aren't sitting somewhere gathering dust for eternity, they just aren't there at all.
My own view is that the finitist approach is the sensible one,
Which finitist approach? An anti realist can regard infinties as suitable objects of study, no less real than other numbers.
The wellspring of the debate is a confrontation between phenomenology—the phenomena of mathematical reasoning and mathematical knowledge—and natural science—the apparent finitude of the information processing that can occur in the human brain.
Perhaps, but the phenomenological argument is really weak. Phenomenology is strong evidence of phenomenality..if it things seems to you to be certain way,then that is evidence that somethings seems so some way to you...but weak evidence of anything else.
But neither side can anchor its intuitions in a clear picture of how mathematical thinking is related to neuronal processes,
There isn't the slightest evidence that mathematical thinking is non neuronal or otherwise unusual ... from.neuroscience.
or even a principled answer to the general Searlean question of how brain states “represent” or manage to “be about” mathematics.
Under the form of anti realism known as fictionalism , there is no problem...the brain simply conjures up mathematical objects like dragons and werewolves.
It is the form of realism known as Platonism that causes the problems, since it needs to explain how immaterial entities affect thought, and therefore neural activity.
You could say that the Feferman completeness of human thought, is what allows us to prove the Gödel incompleteness of a formal system;
I wouldn't:understanding GIT might require some leveling meanness, but doesnt require transfinite levels....
and the debate between Penrose and cog-sci common sense, is a debate over whether human thought isn’t literally Feferman-complete, but only extends some basic axiom system by a few rounds of reflection;
...as you say.
My own interest in quantum mind theories derives especially from the belief that physical theories of mind have a severe sorites problem (one dimension of which you can see in this ongoing discussion)
That's another unnecessary problem. There's actually lots of evidence that consciousness is non binary.
* Drowsiness, states between sleep.and waking.
* Autopilot and flow states , where the sense of a self deciding actions isn absent.
More rarely there are forms of heightened consciousness: peak experiences, meditations jñanas, psychedelic enhanced perceptions , etc.
, and that quantum entanglement, and fundamental physics in general, offer a way out in the form of entities which are “wholes” with complex internal structure and non-arbitrary boundaries.
Like Chalmers , I don't see why any mathematical structure would have associated qualia.
Nobel laureates and lab heads and the most cited researchers in the field are saying there’s a real issue here
Some do, others dont. A lot of people are smart enough to spot cherry picking.
I don’t think this is generally correct. Induction is about moving probability mass to both parameters and models that best explain the evidence
Is it? That isn't the classic definition. The classic definition is fairly limited, more like:-
Example: “For the past 7 days it has been raining. Therefore, tomorrow it will probably also rain.”
Ie, just more of the same , not an infinite variety of models
It does sounds like Bayes,...but Bayes could be a superset of induction.
And where are you getting your models from? If you are creating them , that's abduction, even if you are calling it induction. If they they are already there, in some oracular database, that's uncomputable ideal reasoning.
This is a Machine Learning friendly way to see induction
Or it's something in ML that has been mislabelled "induction", like "hallucination"
Bayes is complete: there is no other theorem or formula required to achieve the most accurate estimate of probability for beliefs
Complete what? It isn't complete epistemology as I have shown.
(Also, Bayesian statistics is considered a subset of inferential statistics, which is the formal mathematics associated with induction
What does "associated with" mean? If inferential stats is a superset of induction it's pretty unsurprising that it could contain abduction. If your models are being created on the fly, it actually does.
I was originally considering the standpoint of an “optimal Bayesian” who simultaneously evaluates all hypotheses at once by shifting probability mass, but this is far from the human experience
Indeed. If ideal Bayesians don't need abduction, that doesn't mean humans don't.
focus on generating hypotheses/explanations/models
Why is that a bad thing?
That implies different permissible levels of making and breaking assumptions, choosing and changing models. It’s more fluid, less rule-bound, more willing to accept being knowingly wrong in some ways, less tied to formalisms and precise methods.
Yes. Hypothesis generation isn't mechanical or algorthmic. That may be "bad", but there's not much alternative -- you can't actually use Solomonoff Induction, or whatever.
I think we could potentially have knowledge of the mathematical and physical structures that give rise to particular types of experiences in general. In this case, a first-person experience could indeed be defined
Only as the subjective thingy that arises from.an objective thingy. We can do that already -- red is what you see when you look a tomato. That isn't a definition of a subjective quality in the Mary's Room sense.
However, I don’t think that consciousness is a concept which is coherent enough formally defined
I think the word "consciousness" labels several concepts that can be coherently defined.
See related ideas from Michael Levin and Emmett Shear.
I tend to find that sort of thing underwhelming. You can point at some objective thing, and say it's subjective..but why? Explanations need to be explanatory.
Or you can.adopt some.camp.#1 definition of consciousness that doesn't include the subjective.
Simplicity and consistency are then factors that positively affect the probability of a belief being true, but they are not in themselves determinants of the “best” explanation
If that is so, you no longer have an argument that abduction is merely a form of induction, because you have admitted to two sources of probability other than induction.
The underlying issue is that what we are trying to do with abduction is find the hidden mechanism behind the directly observable, the force of gravity that makes the apple fall. Since induction is limited to inferring futures observations from past ones, it is limited to the observable and silent about behind-the-scenes mechanisms. And so it is limited compared to abduction, and so abduction is not a form of induction. ( The classic argument against induction is that it is not a form of deduction...within classical loguic. It could still be a form of probabilistic reasoning).
Bayes allow you to confirm hypotheses that would generate the observable evidence, but doesn't mechanically generate them for you , and also.doesn't allow you to distinguish equally predictive ones. You can solve the first problem by creatively positing hypotheses, and the second with the criteria of simplicity and consistency. That gives you full abductive reasoning . Bayes is a subset of full abductive reasoning.
Science uses abductive reasoning , plus (dis)confirmation. Deduction is needed for these, because you need to deduce the expected consequences of a theory to observe them.
Assuming the probabilities are correct, I think Belief A should be considered the “best”. Would you agree with this?
I would need to know where you are getting your likelihoods from. Are they hard observational data, or subjective priors?
Quantum field theory is an example of a very complex theory and inconsistent with other accepted theories (e.g. General Relativity), but still the “best” explanation for empirical evidence
Simplicity is a relative measure, not an absolute. QFT can both a complex theory, and the simplest that does the job.
@Viliamand
This reasoning is okay in our world, because we have the prior that among diseases that have these three symptoms, flu is most frequent. But this is an extra information that is not included in the quote.
Yes, we need to know where the likelihood is coming from.
Probabilistic reasoning is also induction, so long as induction isn't required to be certain: observing multiple instances of something in the past raises the probability that it occur again in the future.
@AnthonyCand
this case, my own (not at all formal, just my sense) understanding is that while induction and deduction are largely about interpreting and reasoning regarding facts/data, abduction is largely about applying, proposing, and evaluating models and heuristics
Not really. they have standard definitons you can just look up. You don't have to guess.
Bayes factors come from metaphysical assumptions and concept groupings
Well, Bayesian updates are no good unless you have the right hypothesis. That might be what you mean.
I find it useful to think in terms of failure modes: inductive reasoning is the sort of reasoning that tends to fail because you overestimated the strength of the existing evidence, abductive reasoning is the sort of reasoning that tends to fail because you didn’t evaluate the direction of the existing evidence well (maybe you over-weighted something, maybe you’re missing a possible hypothesis and hence a direction in possibility space, etc.
It's naive to assume that explanations are suggested by the data. They are conjectured.
"it" isn't a single theory.
The argument that Everettian MW is favoured by Solomonoff induction, is flawed.
If the program running the SWE outputs information about all worlds on a single output tape, they are going to have to be concatenated or interleaved somehow. Which means that to make use of the information, you gave to identify the subset of bits relating to your world. That's extra complexity which isn't accounted for because it's being done by hand, as it were..