I should note that Russell was also led in some pretty weird directions by the desire to resist skeptical arguments:

What distinguishes neutral monism from its monistic rivals is the claim that the intrinsic nature of ultimate reality is neither mental nor physical. [...] Following a series of critical engagements with neutral monism (see especially Russell 1914a,b), Russell adopted it in Russell 1919 and remained a neutral monist for the rest of his long career: “I am conscious of no major change in my opinions since the adoption of neutral monism” is what he says in an interview from 1964 (Eames 1969: 108). [...]
For an entity to be neutral is to “have neither the hardness and indestructibility of matter, nor the reference to objects which is supposed to characterize the mind” (Russell 1921: 36; cf. 124). Russell never suspected sensations of being material (in this sense). That sensations are mental (in this sense)—that they consist of a mental act of sensing directed at a non-mental object—was, however, a pivotal part of his earlier view. But then his views changed:
"I formerly believed that my own inspection showed me the distinction between a noise [the object] and my hearing of a noise [the act of sensing], and I am now convinced that it shows me no such thing, and never did." (Russell 1918b: 255)

Also, insofar as Moore and Russell are gesturing at similar issues, Moore's paper provides some support for the claim that master-argument-ish reasoning was central to the idealism and rested on a simple error that was concealed by motivated reasoning and obfuscatory language, and that no one noticed (or successfully popularized) the error prior to Moore/Russell:

I am suggesting that the Idealist maintains that object and subject are necessarily connected, mainly because he fails to see that they are distinct, that they are two, at all. When he thinks of 'yellow' and when he thinks of the 'sensation of yellow', he fails to see that there is anything whatever in the latter which is not in the former. [...]
But I am well aware that there are many Idealists who would repel it as an utterly unfounded charge that they fail to distinguish between a sensation or idea and what I will call its object. And there are, I admit, many who not only imply, as we all do, that green is distinct from the sensation of green, but expressly insist upon the distinction as an important part of their system. They would perhaps only assert that the two form an inseparable unity.
But I wish to point out that many, who use this phrase, and who do admit the distinction, are not thereby absolved from the charge that they deny it. For there is a certain doctrine, very prevalent among philosophers nowadays, which by a very simple reduction may be seen to assert that two distinct things both are and are not distinct. A distinction is asserted; but it is also asserted that the things distinguished form an 'organic unity'. But, forming such a unity, it is held, each would not be what it is apart from its relation to the other. Hence to consider either by itself is to make an illegitimate abstraction.
The recognition that there are 'organic unities' and 'illegitimate abstractions' in this sense is regarded as one of the chief conquests of modern philosophy. But what is the sense attached to these terms? An abstraction is illegitimate, when and only when we attempt to assert of a part - of something abstracted - that which is true only of the whole to which it belongs: and it may perhaps be useful to point out that this should not be done. But the application actually made of this principle, and what perhaps would be expressly acknowledged as its meaning, is something much the reverse of useful. The principle is used to assert that certain abstractions are in all cases illegitimate; that whenever you try to assert anything whatever of that which is part of an organic whole, what you assert can only be true of the whole. And this principle, so far from being a useful truth, is necessarily false. For if the whole can, nay must, be substituted for the part in all propositions and for all purposes, this can only be because the whole is absolutely identical with the part.
When, therefore, we are told that green and the sensation of green are certainly distinct but yet are not separable, or that it is an illegitimate abstraction to consider the one apart from the other, what these provisos are used to assert is, that though the two things are distinct yet you not only can but must treat them as if they were not. Many philosophers, therefore, when they admit a distinction, yet (following the lead of Hegel) boldly assert their right, in a slightly more obscure form of words, also to deny it. The principle of organic unities, like that of combined analysis and synthesis, is mainly used to defend the practice of holding both of two contradictory propositions, wherever this may seem convenient.
In this, as in other matters, Hegel's main service to philosophy has consisted in giving a name to and erecting into a principle, a type of fallacy to which experience had shown philosophers, along with the rest of mankind, to be addicted. No wonder that he has followers and admirers. [...]
And at this point I need not conceal my opinion that no philosopher has ever yet succeeded in avoiding this self-contradictory error: that the most striking results both of Idealism and of Agnosticism are only obtained by identifying blue with the sensation of blue: that esse ["existing"] is held to be percipi ["being perceived"], solely because what is experienced is held to be identical with the experience of it. That Berkeley and Mill committed this error will, perhaps, be granted: that modern Idealists make it will, I hope, appear more probable later.

This updates me partway back toward the original claim I made (that Berkeley's master argument was causally important for the rise of idealism and its 20th-century successors).

A simple sketch of how realism became unpopular

by Rob Bensinger 3 min read11th Oct 201953 comments


[Epistemic status: Sharing current impressions in a quick, simplified way in case others have details to add or have a more illuminating account. Medium-confidence that this is one of the most important parts of the story.]

Here's my current sense of how we ended up in this weird world where:

  • I still intermittently run into people who claim that there's no such thing as reality or truth;
  • a lot of 20th-century psychologists made a habit of saying things like 'minds don't exist, only behaviors';
  • a lot of 20th-century physicists made a habit of saying things like 'quarks don't exist, only minds';
  • there's a big academic split between continental thinkers saying (or being rounded off to saying) some variant of "everything is culture / perception / discourse / power" and Anglophone thinkers saying (or being rounded off to saying) "no".

Background context:

1. The ancient Greeks wrote down a whole lot of arguments. In many cases, we're missing enough textual fragments or context that we don't really know why they were arguing — what exact propositions were in dispute, or what the stakes were.

2. In any case, most of this is screened off by the fact that Europe's memetic winners were Christianity plus normal unphilosophical beliefs like "the sky is, in fact, blue".

3. Then, in 1521, the Protestant Reformation began.

4. In 1562, the Catholics found a giant list of arguments against everything by the minor Greek skeptic Sextus Empiricus, got very excited, and immediately weaponized them to show that the Protestant arguments fail (because all arguments fail).

5. These soon spread and became a sensation, and not just for being a useful superweapon. Plenty of intellectuals were earnest humanists used to taking arguments at face value, and found Sextus' arguments genuinely upsetting and fascinating.

I trace continental thinkers' "everything is subjective/relative" arguments back to a single 1710 error in George Berkeley:

[...] I am content to put the whole upon this Issue; if you can but conceive it possible for one extended moveable Substance, or in general, for any one Idea or any thing like an Idea, to exist otherwise than in a Mind perceiving it, I shall readily give up the Cause[....]
But say you, surely there is nothing easier than to imagine Trees, for instance, in a Park, or Books existing in a Closet, and no Body by to perceive them. I answer, you may so, there is no difficulty in it: But what is all this, I beseech you, more than framing in your Mind certain Ideas which you call Books and Trees, and the same time omitting to frame the Idea of any one that may perceive them? But do not you your self perceive or think of them all the while? This therefore is nothing to the purpose: It only shews you have the Power of imagining or forming Ideas in your Mind; but it doth not shew that you can conceive it possible, the Objects of your Thought may exist without the Mind: To make out this, it is necessary that you conceive them existing unconceived or unthought of, which is a manifest Repugnancy.

If I can imagine a tree that exists outside of any mind, then I can imagine a tree that is not being imagined. But "an imagined X that is not being imagined" is a contradiction. Therefore everything I can imagine or conceive of must be a mental object.

Berkeley ran with this argument to claim that there could be no unexperienced objects, therefore everything must exist in some mind — if nothing else, the mind of God.

The error here is mixing up what falls inside vs. outside of quotation marks. "I'm conceiving of a not-conceivable object" is a formal contradiction, but "I'm conceiving of the concept 'a not-conceivable object'" isn't, and human brains and natural language make it easy to mix up levels like those.

(I can immediately think of another major milestone in the history of European thought, Anselm's ontological argument for God, that shows the same brain bug.)

Berkeley's view was able to find fertile soil in an environment rife with non-naturalism, skeptical arguments, and competition between epistemic criteria and authorities. Via Kant and Kant's successors (Hegel chief among them), he successfully convinced the main current of 19th-century European philosophy to treat the idea of a "mind-independent world" as something ineffable or mysterious, and to treat experiences or perspectives as fundamental.

(Edit: G.E. Moore seems to think that everyone in the 19th century was making an error along these lines, but I now suspect Kant himself wasn't making this mistake; I think his main error was trying too hard to defeat skepticism.

I also don't think Berkeley's writing would have been sufficient to confuse Europe on its own; it's too lucid and well-articulated. The transition to Kantian and Hegelian versions of these arguments is important because they were much more elaborate and poorly expressed, requiring a lot of intellectual effort in order to spot the inconsistencies.)

My unscholarly surface impression of the turn of the 20th century is that these memes ("the territory is fundamentally mysterious" and "maps are sort of magical and cosmically important") allowed a lot of mysticism and weird metaphysics to creep into intellectual life, but that ideas like those are actually hard to justify in dry academic prose, such that the more memetically fit descendants of idealism in the 20th century ended up being quietist ("let's just run experiments and not talk about all this weird 'world' stuff") or instrumentalist / phenomenalist / skeptic / relativist ("you can't know 'world' stuff, so let's retreat to just discussing impressions; and maybe you can't even know those, so really what's left is power struggles").

Today, the pendulum has long since swung back again in most areas of intellectual life, perhaps because we've more solidly settled around our new central authority (science) and the threats to centralized epistemic authority (religious and philosophical controversy) are more distant memories. Metaphysics and weird arguments are fashionable again in analytic philosophy; behaviorism is long-dead in psychology; and quietism, non-realism, and non-naturalism at least no longer dominate the discussion in QM, though a lot of Copenhagen slogans remain popular.

The above is a very simple picture featuring uneven scholarship, and history tends to be messier than all that. (Ideas get independently rediscovered, movements go one step forward only to retreat two steps back, etc.) Also, I'm not claiming that everyone endorsed the master argument as stated, just that the master argument happened to shift intellectual fashions in this direction in a durable way.