Moore’s philosophy is famous because it looks harder to attack than to admire, yet the very features that make it appealing also make it vulnerable. The first and most obvious criticism is that his “proof” of the external world does not seem to satisfy the skeptic’s standards. The skeptic asks not merely whether we have hands, but whether we can know that we are not dreaming, deceived, or otherwise mistaken. Moore replies that he knows he has hands. Critics say this simply refuses the skeptic’s challenge rather than answering it.
The most influential critique came from Ludwig Wittgenstein, whose late remarks on certainty, gathered after his death in On Certainty, treat Moore with both respect and disagreement. Wittgenstein thought Moore had identified something deeply important—the special role of hinge propositions, those commitments we do not usually doubt—but that Moore misdescribed their logic by calling them propositions known in the ordinary sense. Some things are not inferred; they stand fast in our practices. The tension here is subtle and profound: Moore thinks he defeats skepticism by asserting a very ordinary truth, while Wittgenstein thinks the very grammar of certainty changes once a proposition functions as a hinge.
A second critique comes from the internal side of Moore’s own method. If common sense is the court of appeal, which common sense counts? Ordinary people have often held contradictory beliefs, and science routinely revises everyday appearance. Moore’s critics argued that his appeal to the obvious can look selective. Why trust common sense about hands, but not about causation, morality, or mind? The problem is not that common sense is useless, but that it can be too elastic to serve as a final tribunal without further argument.
In ethics, the open question argument generated its own field of dispute. Philosophers sympathetic to Moore granted that “good” cannot be casually reduced to a natural property, yet they disputed whether the open question shows irreducibility in the strong sense Moore wanted. Some argued that the continued intelligibility of the question reflects only linguistic flexibility, not metaphysical independence. Others thought Moore had identified an important feature of moral thought but had overstated the epistemic authority of intuition. The moral world may not be identical with nature, but that does not automatically establish the kind of non-natural realism Moore defended.
A striking tension lies in Moore’s reliance on intuition. He thought that some truths are known directly, or at least recognized without proof. But critics asked: which intuitions, and why these? If intuition is the foundation, then disagreement becomes hard to adjudicate. Moore’s moral theory especially depends on the claim that people can see intrinsic goods, yet history gives abundant examples of intelligent, sincere disagreement about value. The price of Moorean self-evidence is that it can start to look less like certainty and more like confidence.
Another pressure point appears when Moore’s anti-skeptical method is pushed to its limits. If I can know that I have hands, can I know everything required to defeat skepticism? Or does the skeptic simply shift ground, asking about memory, induction, or the reliability of perception? Moore’s strategy is strongest when it preserves ordinary beliefs, weaker when the challenge concerns the conditions that make such beliefs possible. The skeptic may concede the hand and still question the bridge from appearance to knowledge.
There is also the problem of explanatory depth. Moore often resists metaphysical speculation, but philosophy sometimes wants more than resistance. Critics sympathetic to Idealism thought he replaced a system with a series of assertions. To say the world contains hands is true enough, they would concede, but philosophy should explain what kind of reality hands have, how minds relate to them, and why the world is knowable at all. Moore seemed, to these critics, to stop where explanation ought to begin.
Yet a fair judgment must also notice the cost of the opposing positions. Skeptical and system-building philosophies often promise rigor but deliver alienation from ordinary life. Moore’s great virtue is that he exposes this cost. If a theory makes it seem irrational to believe in hands, tables, friends, and the ordinary furniture of the world, then perhaps the theory has overreached. His opponents may be right that his reply is not a technical refutation. But they must still explain why their more technical route should be preferred to the world it places in doubt.
This is why Moore’s critics never quite bury him. Wittgenstein softens him, later ordinary-language philosophy develops him, and metaethics revises him, but the challenge remains. A philosopher who doubts the world must still confront the fact that most human beings, most of the time, do not. Moore’s opponents are right that he does not settle every skeptical puzzle. He is right that skepticism loses something important if it detaches itself from the life in which knowledge actually occurs.
The fire therefore leaves him both damaged and intact. His arguments are not final weapons, but they are durable instruments. They expose philosophical inflation, even when they do not silence philosophical doubt. What remains to be asked is why this modest-seeming resistance had such a long afterlife, and how a man who answered skepticism by holding up his hand came to shape so much of twentieth-century philosophy.