Concept

Mooreanism

Intro

A philosopher comes up to you and says, "How do you know you're not a brain in a vat being fed fake experiences by an evil scientist? You can't prove you're not. So you don't really know anything about the outside world." Most people freeze. The argument feels airtight.

G.E. Moore had a simple answer. He held up his hand in a lecture and said, in effect: "Here is one hand. Here is another. So there is an external world. The rest of your clever argument has to be wrong somewhere, even if I can't tell you which step failed."

That sounds like cheating until you think about it. Both sides of the debate accept some claims and reject others. The skeptic accepts his abstract premises and rejects ordinary knowledge. Moore accepts ordinary knowledge and rejects whatever abstract premise leads to denying it. Both moves use the same logical structure (modus tollens). The question is which is more obviously true: that I have hands, or that some abstract premise about closure-of-knowledge holds in every weird scenario?

Moore says the hands win. He knows he has hands more securely than he knows any abstract philosophical premise. So if a premise leads to "you don't have hands," the premise loses. The skeptic owes us a reason to think his premises are more secure than the obvious facts they would overturn.

This matters for theology too. Reformed epistemologists like Alvin Plantinga use a Moorean structure for belief in God. The skeptic says, "You have no proof God exists; therefore you don't know He does." The Plantinga reply is structurally Moorean: I know God exists more securely than I know the skeptic's epistemological framework is correct. So if his framework leads to "you can't know God," the framework loses.

Quick reply: "Which is more obvious: that I have hands, or that I need a separate proof I'm not a brain in a vat? The argument runs both directions; we just disagree which end gives way first."

In full

The anti-skeptical strategy named for G. E. Moore (1873-1958), British philosopher of the early-20th-c. "common sense" school. The signature move is to take the conclusion of the skeptical argument as more incredible than its premises and run the argument in reverse by modus tollens: since I clearly do know I have hands, and (by closure) my having hands entails my not being a brain in a vat, I therefore know I am not a brain in a vat, even though I have no inferential argument that distinguishes my situation from a BIV's. Mooreanism shifts the burden of proof: the skeptic must show why my common-sense knowledge of the external world is less secure than her abstract premises, and the Moorean contends that she cannot.

Moore's two papers

Two short Moore papers anchor the position:

"Proof of an External World" (1939)

Moore's most famous argument is here. Holding up his hands in a lecture, Moore says:

"I can prove now, for instance, that two human hands exist. How? By holding up my two hands, and saying, as I make a certain gesture with the right hand, 'Here is one hand,' and adding, as I make a certain gesture with the left, 'and here is another.' And if, by doing this, I have proved ipso facto the existence of external things, you will all see that I can also do it now in numbers of other ways: there is no need to multiply examples."

The argument has the form of a proof:

(P1) Here is one hand. [Premise]
(P2) Here is another. [Premise]
(C) Therefore at least two human hands exist outside us. [Conclusion]

Moore explicitly considers this an instance of modus ponens against the skeptic. He grants that he cannot give an argument for the premises, he simply knows them. But he argues that he is more certain of the premises than he is of any premise of any skeptical argument that would deny them. Therefore, by modus tollens, the skeptical argument's premises must be wrong somewhere, even if he cannot say exactly where.

"A Defence of Common Sense" (1925)

Moore lists a series of common-sense propositions ("the truisms") which he claims to know with certainty:

I have a body
The body has existed for some years
During this time the body has been in contact with the surface of the earth
Other human beings exist with bodies of their own
These other humans have had thoughts, feelings, and experiences -... and so on

Moore argues that any philosophical view that denies these truisms is mistaken, and not merely mistaken but obviously so, since the truisms are more secure than any premise of any philosophical argument that would deny them.

The Moorean argument structure

Mooreanism formalizes the modus tollens against Cartesian skepticism. The skeptic's argument:

(P1) I do not know I am not a BIV.
(P2) If I know I have hands, then I know I am not a BIV. [Closure]
(C) Therefore I do not know I have hands.

The Moorean runs this in reverse:

(P1') I know I have hands. [Common sense]
(P2) If I know I have hands, then I know I am not a BIV. [Closure, accepted]
(C') Therefore I know I am not a BIV.

The Moorean accepts P2 (closure) but rejects the skeptic's P1 (no BIV-knowledge) on the strength of P1' (common-sense knowledge of hands). She acknowledges that she cannot give independent evidence for P1' that wouldn't beg the question against the skeptic; her claim is that she doesn't need to, because P1' is more secure than the skeptic's P1.

The skeptic can complain that this is dogmatism: how can the Moorean simply assert P1' without justifying it against the skeptical scenario? The Moorean's principled reply: this is exactly what the skeptic does with her own P1. Both premises are intuitions; the question is which is more secure. The Moorean argues common-sense knowledge of one's own hands is more secure than abstract reflection on what one might or might not know about exotic skeptical scenarios.

The dogmatist version (Pryor)

James Pryor's "The Skeptic and the Dogmatist" (2000) gives the contemporary technical defense of Mooreanism. Pryor's "dogmatism" (his term, used non-pejoratively) is the thesis that perceptual experience provides immediate (non-inferential) justification for ordinary perceptual beliefs. If perception provides immediate justification, then I have justification for "I have hands" without needing prior justification for "I am not a BIV." So my justification for "I have hands" transfers (via closure) to "I am not a BIV," and I can know I am not a BIV by Moorean reasoning.

The skeptical reply is that Mooreanism (dogmatism) commits the transmission failure: justification for "I have hands" cannot transmit to "I am not a BIV" via closure if the BIV-scenario is exactly the kind of possibility that perceptual experience cannot rule out. Crispin Wright's notion of transmission failure (in "Facts and Certainty," 1985, and many later papers) is the principal technical objection to Mooreanism.

The reflective version (Sosa)

Ernest Sosa's A Virtue Epistemology (2007) develops a more nuanced Mooreanism through the animal vs reflective knowledge distinction:

Animal knowledge, first-order reliably-formed true belief; we have animal knowledge of our hands.
Reflective knowledge, second-order: we know that we know; we have an apt belief about our first-order belief.

Sosa argues that Mooreanism gives us animal knowledge of our hands and (derivatively) of our not being BIVs, but it does not give us reflective knowledge, for reflective knowledge we need to be able to defend the first-order knowledge against challenges, and the BIV scenario is one we cannot fully defeat. So the skeptic is right that we lack a kind of knowledge (reflective) but wrong that we lack knowledge altogether (animal).

This is structurally similar to what Plantinga does in Reformed Epistemology, the believer has warrant (Plantinga's term) for belief in God without needing to provide an argumentative defense, and it has been adopted by some Christian apologists (Robert Audi, Richard Swinburne in his later work).

Strengths

Phenomenological correctness, Mooreanism captures what most people actually find when they introspect: the BIV scenario seems vastly less plausible than the proposition that I have hands. The skeptical argument's premises are strictly weaker than its conclusion's denial.
Refusal to grant the skeptic the high ground, the skeptic typically frames the discussion as "until you defeat my argument I have won." Mooreanism rejects this framing: the skeptic must defeat my common-sense knowledge.
Compatibility with externalism, Mooreanism is naturally allied with reliabilism and externalist epistemology. If our perceptual faculties reliably produce true beliefs about hands, we know we have hands; that we cannot internally rule out the BIV is irrelevant.
Apologetic transferability, the structural move (refusing to let the skeptic set the agenda; insisting the burden of proof is on the challenger) carries directly into Plantinga's Reformed Epistemology and into common-sense apologetics.

Weaknesses

Begs the question against the skeptic, Moore offers no argument for his premises that the skeptic would accept. It is just a clash of intuitions.
Transmission failure (Wright), even granting that I have justification for "I have hands," it does not follow that I have justification for "I am not a BIV" via closure, if the BIV scenario is precisely the possibility my perceptual experience cannot rule out.
Dogmatism worry, refusing to engage skeptical premises looks like simply ignoring the problem.
Asymmetry of argument, Moore takes the direction of the modus tollens to be obvious; but the formal structure is symmetric (the skeptic could equally claim her P1 is more secure than Moore's P1'). Without an independent reason to break the tie, the argument is a stand-off.

Mooreanism vs other anti-skeptical strategies

Strategy	What it accepts	What it denies
Mooreanism	Closure (P2)	The skeptic's P1 (we do know we're not BIVs)
Closure denial (Dretske, Nozick)	The skeptic's P1 (we don't know we're not BIVs)	Closure (so the conclusion doesn't follow)
Contextualism (DeRose, Lewis)	Both premises in their context	The univocity of "know" between contexts
Externalism / Reliabilism	We know we have hands	The internalist demand that we have evidence ruling out BIV
Reformed Epistemology	Belief in God is properly basic	The need for inferential support
Presuppositionalism	Christian theism grounds rationality	The skeptic's right to use rational standards

Mooreanism is closer to contextualism and externalism than to closure-denial; it accepts closure but rejects the skeptic's antecedent. Some contemporary epistemologists (Sosa, Pritchard) hold blends of Moorean and contextualist positions.

Christian apologetic resonances

The Moorean strategy is structurally cognate to several major Christian-apologetic moves:

Plantinga's Reformed Epistemology

Reformed Epistemology's "properly basic belief" doctrine is structurally Moorean: belief in God is, for the believer, more secure than the premises of any argument that would defeat it. Plantinga is explicit about the parallel, Warranted Christian Belief (2000) treats the de facto objection to Christianity (it is false) as needing argument, and the de jure objection (it is unwarranted even if true) as defeated by showing that Christian belief is properly basic if true.

Reidian Common Sense

Thomas Reid (1710-1796) is the Scottish-Enlightenment ancestor of Mooreanism. Reid's common-sense beliefs, beliefs in the existence of the external world, of other minds, of one's own body, of the past, are foundational and incorrigible against any philosophical attack. Reid's strategy was self-consciously a defense of Christianity against Humean skepticism: the "common-sense beliefs" include moral and religious foundations that Hume would have dissolved. Modern Reformed-Christian philosophers (Wolterstorff, Plantinga) have explicitly retrieved Reid.

Classical evidentialism

William Lane Craig and other classical apologists deploy Moorean moves implicitly: the empirical premises of natural-theological arguments (e.g., "the universe began to exist," "the universe is finely tuned for life") are taken to be more secure than the metaphysical premises of arguments that would dispute them. The cumulative case is structurally Moorean in its accumulation of weight against any single skeptical challenge.

Pascal's Wager

Pascal's wager in the Pensées operates in a Moorean register: the practical impossibility of theoretical neutrality between theism and atheism makes the wager a real choice. Pascal accepts a kind of Pyrrhonist suspension on the theoretical question while insisting we cannot suspend on the practical one, a near-Moorean move applied to the religious question.

Practical role of Mooreanism

Even philosophers who reject Mooreanism's argumentative force often find themselves living as Mooreans. The position captures a real datum: we cannot meaningfully suspend judgment about whether we have hands. This makes Mooreanism a strong candidate for what skepticism comes up against psychologically and behaviorally, even if it is dialectically vulnerable. Hume's own observation (radical skepticism evaporates outside the study) is implicitly Moorean.