G.E. Moore: Philosophy, Quotes & Legacy

Biography

George Edward Moore was born on November 4, 1873, in Upper Norwood, a leafy suburb south of London, into a comfortable middle-class family. His father was a medical doctor, and the household valued education and respectability in the manner typical of late-Victorian professional England. Moore was the fifth of six children, and he grew up in an atmosphere that was stable, bookish, and quietly ambitious. He showed early academic promise and won a scholarship to Dulwich College, one of the leading English public schools of the day, where he studied from 1887 to 1891. The curriculum at Dulwich was steeped in the classics, and Moore excelled at Greek and Latin, a proficiency that would shape his philosophical style for the rest of his life. He learned to read Plato and Aristotle in the original, and the precision and rigor of classical philology became a habit of mind he never abandoned.

In 1892, Moore went up to Trinity College, Cambridge, on a scholarship to study classics. He sat the Classical Tripos and performed respectably, but his interests were already drifting toward philosophy. At Cambridge he came under the influence of two very different thinkers. The first was J.M.E. McTaggart, a philosopher of genuinely eccentric personality but formidable dialectical skill, who defended a version of absolute idealism derived from Hegel. McTaggart's lectures introduced Moore to the tradition of British idealism then dominant at Cambridge, a tradition that held reality to be fundamentally spiritual and that the world of separate objects was an illusion. The second influence was Henry Sidgwick, the great utilitarian moral philosopher, whose methods of careful analytic reasoning provided a counterweight to McTaggart's speculative metaphysics. Moore also met a slightly older student named Bertrand Russell, and the two began a friendship that would transform English philosophy.

Russell, two years Moore's senior, had already abandoned his early idealism and was pushing Moore to do the same. The story of how Moore converted Russell to realism is one of the most oft-told episodes in the history of analytic philosophy, and though the details are sometimes embellished, the broad outline is clear. Moore, working through the arguments of idealism on his own, became convinced that the idealist doctrine that esse est percipi — to be is to be perceived — was simply a confusion. In a paper read to the Cambridge Apostles in 1898, Moore argued that consciousness is not identical with its objects but stands in a relation to them, and that those objects exist independently of being perceived. Russell, who had been struggling with the same questions, later wrote that Moore led the way and he followed. Moore and Russell jointly overthrew the British idealism that had reigned at Cambridge since the days of T.H. Green, and in doing so they created the intellectual movement we now call analytic philosophy.

Moore was elected to a Prize Fellowship at Trinity in 1898, which gave him six years of financial freedom to pursue his work. The period that followed was one of extraordinary productivity. He published "The Nature of Judgment" in 1899, a dense but groundbreaking paper in which he argued that propositions are composed of concepts that have being independently of being thought about. In 1903 he published two of his most important works: "The Refutation of Idealism," a direct assault on the idealist principle that reality is essentially mental, and Principia Ethica, the book that would establish him as one of the most important moral philosophers of the century. The Stanford Encyclopedia of Philosophy describes Principia Ethica as the most influential work of moral philosophy in the first half of the twentieth century, a work that defined the agenda for ethics for decades.

After his fellowship expired, Moore spent several years living in Edinburgh with the family of his friend and fellow philosopher A.D. Lindsay. He returned to Cambridge in 1911 as a university lecturer, a position he held until 1925, when he was elected Professor of Philosophy, succeeding McTaggart. He held the chair until his retirement in 1939. From 1921 to 1947 he also served as editor of Mind, the leading philosophy journal in Britain, a position that gave him enormous influence over the direction of professional philosophy in the English-speaking world. He was, by all accounts, a mesmerizing lecturer and a formidable discussant. Ludwig Wittgenstein, who arrived at Cambridge in 1911 and whose relationship with Moore was complex and sometimes fraught, acknowledged Moore's extraordinary intellectual honesty. The two men influenced each other profoundly: Wittgenstein's later philosophy reshaped Moore's thinking about language and meaning, while Moore's common-sense realism provided a foil against which Wittgenstein developed his own views.

Moore married Dorothy Ely in 1916, and the couple had two sons. He was, by the testimony of those who knew him, a man of exceptional personal integrity and kindness, unassuming to the point of shyness, and possessed of a philosophical conscience that would not let him rest until he had examined every assumption of an argument. He died on October 24, 1958, in Cambridge, at the age of eighty-four, having spent nearly his entire adult life in the service of philosophical clarity.

Philosophy

The Naturalistic Fallacy

Moore's most famous contribution to philosophy is the concept of the naturalistic fallacy, introduced in Principia Ethica (1903). The argument is deceptively simple in its formulation but revolutionary in its consequences. Moore observed that previous moral philosophers had almost universally tried to define "good" in terms of something else. Utilitarians defined good as pleasure or happiness. Evolutionary ethicists defined it as what promotes survival. Theological ethicists defined it as what God commands. Metaethical naturalists of various stripes defined it in terms of desire, preference, or some other natural or psychological property. Moore's claim was that all such attempts commit a fundamental error: they confuse a moral property with a non-moral one, and in doing so they distort the very concept they are trying to explain.

To see the force of Moore's argument, consider his analogy with color. If someone asks you what "yellow" is, you cannot define it. You can point to yellow things and you can describe the physical processes that produce the sensation of yellow, but you cannot explain what yellow is to someone who has never experienced it. "Yellow" is a simple, unanalyzable quality, known only by direct acquaintance. Moore argued that "good" is like "yellow" in this respect. It is a simple, non-natural property that cannot be broken down into more basic components. You can point to good things, and you can describe the natural properties that good things tend to have, but you cannot define "good" in terms of those natural properties. As Moore famously declared, if asked what good is, the only honest answer is that good is good, and that is the end of the matter.

The term "naturalistic fallacy" has sometimes been used more broadly than Moore intended. Moore himself used it to cover two related but distinct errors. The first is the attempt to define "good" in terms of natural properties — pleasure, desire, evolutionary fitness, and so on. The second is the attempt to define it in terms of metaphysical properties — what God commands, what the Form of the Good is, and so on. Both, Moore argued, are mistaken because they try to analyze what is simple and unanalyzable. The fallacy is not, strictly speaking, the same as the is-ought problem identified by David Hume, though the two are closely related. Hume pointed out that you cannot derive an "ought" from an "is." Moore pointed out that you cannot define "good" in terms of any natural fact. The former is a point about logical derivation; the latter is a point about meaning and definition.

The Open Question Argument

To support his claim that "good" is indefinable, Moore deployed what has become known as the open question argument. The argument works like this. Suppose someone proposes a naturalistic definition of "good" — say, "good means pleasurable." Moore asks us to consider the question: "Is pleasure good?" If "good" really meant "pleasurable," then the question "Is pleasure good?" would be trivial — it would be like asking "Is a triangle three-sided?" The answer would be obviously yes, by definition. But the question "Is pleasure good?" is not trivial. It is a genuine, open question. Thoughtful people can and do disagree about whether pleasure is good, or whether it is the only good. The fact that the question remains open shows that "good" does not mean the pleasurable. The two concepts are not synonymous.

The argument is completely general. Try any natural property you like — desire, happiness, evolutionary fitness, preference satisfaction — and ask whether that property is good. For any candidate, the question remains open. "Is what we desire good?" "Is evolutionary fitness good?" "Is preference satisfaction good?" None of these questions is trivial. None can be answered by definition alone. And since the question is open for every natural property we might propose, "good" cannot be identical with any of them. It must be a distinct, indefinable property.

The open question argument has been enormously influential, but it has also attracted serious criticism. Some philosophers have argued that it proves too much. If the argument works against naturalistic definitions of "good," it would seem to work against any proposed synonymy. "Is water H2O?" is an open question for someone who does not know chemistry, but that does not show that "water" and "H2O" have different meanings. The open question test, on this view, tracks ignorance rather than genuine semantic distinctness. Others have argued that Moore conflates two different senses of "definition" — a real definition (specifying the nature of a thing) and a nominal definition (specifying the meaning of a word). Despite these criticisms, the argument remains a touchstone of metaethical debate. Any naturalistic moral theory must explain why the open question argument fails, and the way it answers that challenge largely determines its character.

Moral Non-Naturalism and Metaethics

If "good" is a simple, non-natural property that cannot be defined in naturalistic terms, how do we come to know it? Moore's answer is moral intuition. We recognize goodness in the same way that we recognize yellow — by direct acquaintance with the quality itself. When we contemplate certain states of affairs — friendship, beauty, the enjoyment of great art — we intuit that they are good. This does not mean that moral knowledge is mysterious or supernatural. It means that moral perception is a form of direct apprehension, analogous to sense perception, in which we grasp a non-natural property by attending to the object that possesses it.

This position is known as moral non-naturalism, and it set the terms for twentieth-century metaethics. Moore divided moral philosophy into two branches: ethics as the investigation of what things are good (the substantive ethical inquiry), and metaethics as the investigation of what "good" means (the conceptual inquiry). Principia Ethica is primarily a work of metaethics, and its most enduring legacy is the way it separated questions about the meaning of moral language from questions about which actions are right. This separation made it possible for later philosophers to ask whether moral statements express truths (cognitivism) or attitudes (non-cognitivism), whether moral properties are natural or non-natural, and whether moral knowledge is empirical, intuitive, or constructed — questions that continue to animate moral philosophy today.

Intrinsic Value and the Ideal

The second half of Principia Ethica is devoted to substantive ethics — to the question of what things are actually good. Moore argued that the most valuable things we know or can imagine are certain states of consciousness, which may be roughly described as the pleasures of human intercourse and the enjoyment of beautiful objects. He famously wrote that, by far, the most valuable things which we know or can imagine are certain states of consciousness, which may be roughly described as the pleasures of human intercourse and the enjoyment of beautiful objects. This was not hedonism; Moore insisted that the value of these states does not reduce to the pleasure they produce. Pleasure is one component of the good, but beauty and personal affection have intrinsic value that cannot be captured by pleasure alone.

This aspect of Moore's thought had consequences far beyond academic philosophy. His emphasis on the intrinsic value of beauty, friendship, and personal relationships profoundly influenced the Bloomsbury Group — the circle of writers, artists, and intellectuals that included Virginia Woolf, John Maynard Keynes, Lytton Strachey, and Leonard Woolf. These men and women had known Moore at Cambridge, and they carried his ethical vision into literature, economics, and cultural criticism. Keynes later wrote that Principia Ethica had been the guiding text of their generation, and that Moore's distinction between intrinsic and instrumental value shaped their conviction that art, friendship, and the pursuit of truth were ends in themselves, not means to some further end.

The Defense of Common Sense

In 1925, Moore published "A Defence of Common Sense," a paper that took his philosophical work in a new direction. The paper begins with a list of truisms — propositions that Moore claims to know with certainty. Among them: that there exists at present a living human body that is his body; that this body has been continuously located on or near the surface of the earth for many years; that he has had many different experiences (perceptions, thoughts, feelings); and that many other human bodies have existed and have had similar experiences. Moore insisted that these propositions are all certainly true and that he knows them to be true.

The philosophical point was not that common sense is infallible or that it settles all philosophical questions. It was that any philosophical theory that entails the denial of these truisms must be false. If a philosopher argues that we cannot know there is an external world, or that time is unreal, or that other minds do not exist, then that philosopher's argument must contain an error somewhere — because the conclusion contradicts things we know with certainty. Moore was not offering a theory of knowledge or a refutation of skepticism in the traditional sense. He was issuing a challenge: explain how we know these common-sense truths, but do not deny that we know them.

This approach had a profound influence on later philosophy. Ludwig Wittgenstein took Moore's common-sense truisms as the starting point for his late reflections on certainty, arguing that such propositions function as the bedrock of our language games — the unquestioned background against which all inquiry takes place. The ordinary language philosophers at Oxford, including J.L. Austin and Gilbert Ryle, drew on Moore's respect for ordinary usage and common-sense conviction. And Moore's insistence that philosophy must not contradict what we all know set a standard of intellectual honesty that became a hallmark of the analytic tradition.

Proof of an External World

In 1939, Moore delivered his most famous argument: the proof of an external world. Standing before the British Academy, he held up his hands and said, in effect, "Here is one hand, and here is another. Therefore, there are external objects." The argument is a simple modus ponens: if these are hands, then external objects exist; these are hands; therefore, external objects exist. Moore insisted that this is a perfectly good proof. It is logically valid, the premises are true, and he knows the premises to be true. What more could a proof require?

The argument provoked a storm of controversy. Critics, including Wittgenstein, argued that Moore had not refuted skepticism so much as changed the subject. The skeptic's question is not whether Moore has hands but whether he can know he has hands, given the possibility of radical deception. Moore's proof assumes the very thing the skeptic questions — the reliability of perception — and so, the critic says, it begs the question. Moore's defenders respond that this gets the burden of proof backward. The skeptic asks us to doubt what we know, but Moore insists that we do know it, and that the burden is on the skeptic to explain why our knowledge should be impossible. The debate continues to this day, and Moore's proof remains one of the most discussed arguments in epistemology.

Influence on Analytic Philosophy

Moore's influence on the development of analytic philosophy is difficult to overstate, and it operates on several levels. The first is methodological. Moore's philosophical style — his patient attention to the actual meanings of words, his refusal to accept grand theories that distort ordinary usage, his insistence on clarity and precision — became the model for the analytic tradition. Where Russell brought the tools of formal logic to bear on philosophical problems, Moore brought the tools of conceptual analysis. Together, they established the methodological norms that would govern English-language philosophy for most of the twentieth century.

The second level is substantive. Moore's metaethical arguments in Principia Ethica reshaped moral philosophy. By arguing that "good" is indefinable and that any attempt to define it commits the naturalistic fallacy, Moore made it impossible for subsequent moral philosophers to simply identify the good with pleasure, desire, or any other natural property without addressing his challenge. The result was a century of metaethical inquiry into the meaning of moral language — into whether moral statements express truths or attitudes, whether moral properties are natural or non-natural, and whether moral knowledge is possible. Emotivism, prescriptivism, moral realism, and error theory all developed in direct response to the questions Moore raised.

The third level is the defense of common sense. Moore's insistence that philosophy must not contradict what we all know became a touchstone for the tradition of ordinary language philosophy and for later work on skepticism and knowledge. His influence on Wittgenstein's On Certainty is particularly significant: Wittgenstein's late reflections on the role of hinge propositions — the unquestioned certainties that ground all inquiry — are a direct response to Moore's common-sense papers.

Legacy

G.E. Moore died in 1958, but his philosophical influence has not diminished. The naturalistic fallacy and the open question argument remain central to metaethics, and virtually every introductory ethics course engages with them. The defense of common sense continues to shape debates about skepticism, knowledge, and the limits of philosophical theorizing. And Moore's methodological example — his patient, honest, meticulous analysis of concepts — remains the ideal to which much analytic philosophy aspires.

What makes Moore's legacy distinctive is not just the specific arguments he produced but the spirit in which he produced them. He had no interest in building a grand philosophical system. He was suspicious of metaphysical ambition and allergic to the kind of sweeping speculation that produces more heat than light. He believed that philosophical progress comes not from bold theorizing but from careful attention to the meanings of words and the structure of our concepts. This conviction — that clarity is a philosophical virtue and that confusion is the root of most philosophical error — is perhaps his most enduring contribution. The Stanford Encyclopedia of Philosophy notes that Moore, more than any other single figure, established the style and standards of the analytic tradition, and that his work continues to set the agenda for inquiry into the nature of goodness, knowledge, and reality. As the Internet Encyclopedia of Philosophy observes, Moore's career demonstrates that the patient analysis of a single concept can transform an entire field, and that the most revolutionary philosophy sometimes consists not in constructing new theories but in showing that the old ones rested on mistakes.