What are epistemologists for? One conception of the role of the philosophical theorist of knowledge has a consoling quality. It appeals to the epistemologist by assigning him a reasonably dignified position, and to the generally interested public, which it sees as his clients, it has the merit of taking him to be socially useful. This is the conception of him as the professional guardian of the standards of rationality. Beliefs abound, reasons are adduced in support of them, claims to knowledge are advanced. The task of the epistemologist, on this view, is to act as an umpire who closely observes all this cognitive play and blows his whistle when the rules of justified belief are infringed.

The run-of-the-mill epistemologist deals with the beliefs of ordinary men: that there are chairs and tables, people other than oneself who think and feel, past events and future probabilities. There is also the more specialized trade of scrutinizing the claims made in particular disciplines: history, the natural and social sciences, theology, the criticism of art and literature, psychology, and what may be called substantive ethics, the reasoned affirmation of principles of conduct.

On this view epistemology is, if a science at all, a normative one, an ethics of belief, in W. K. Clifford’s phrase, that aims to lay down principles for discriminating justified beliefs from unjustified ones. C. I. Lewis certainly thought of epistemology in this way and, indeed, in very much these terms. He constantly stressed the analogy between logically right thinking and morally right action.

There is something a little vaunting and Promethean about this notion, since it suggests that the epistemologist is somehow above and detached from the cognitive strivings he surveys. Some philosophers have tried to avoid any such immodesty, influenced, perhaps, by the thought that their own discipline is itself just one among many ways in which beliefs are formed and claims to knowledge made.

Three different versions of a humbler idea of epistemology have some currency. First, there is the view of linguistic philosophers that the epistemologist should do no more than describe the rules to which, in their understanding of words like “know,” “believe,” “certain,” and “probable,” their non-philosophical users are already committed. His task is to remind, not to legislate. Secondly, there is the view recently expressed by Quine that epistemology is a part of psychology, an account of the mental and linguistic mechanisms through which beliefs are formed, compete, and persist. Finally, there is the conventionalist view, held at one time by Carnap, which sees the epistemologist as a kind of conceptual entrepreneur, more specifically as a cognitive management-consultant, who devises possible systems of belief-formation and offers them to anyone interested in replacing unreflective habits with an explicit policy.

I do not believe that epistemology can be neutral to this degree. The linguistic philosopher’s description is critically selective and the whole point of the rules he propounds is to exclude some actual reasonings and beliefs from their scope. Of course the epistemologist does not prescribe ex nihilo, like Rousseau’s legislator, to a constituency of cognitive barbarians; he has to build on their fitful intimations of rationality. But his standpoint is inescapably corrective and critical.

However, it is one thing for epistemologists to claim this role, a very different thing for the claim to be effectively admitted by the public at large. It might seem that, for the most part, epistemologists, like contemporary poets, communicate only with each other. If they are to have an influence it must be through the students who pass through their hands and return to the outside world with improved and explicit standards. The exponents of other intellectual disciplines, to whom the epistemologist’s more specific injunctions are addressed, are commonly reluctant to receive correction.

There was a notable example of such resistance in this Review some time ago when J. H. Hexter applied the ethics of historical reasoning propounded by Morton White to a test case, Mattingly’s Defeat of the Spanish Armada. For Hexter, Mattingly’s book was an incontrovertible example of genuine historical knowledge. Since it did not remotely comply, in his view, with White’s specifications, the latter could be regarded as fit only for ornament, not for use.

There is one feature of the history of philosophical theorizing about knowledge that is a little at odds with the notion I have been considering of the epistemologist as a socially useful being in his role as critic of our intellectual processes. This is that the greatest epistemologists, by common acceptation, have all defended more or less wild, indeed radically subversive, conceptions of the genuine and proper pursuit of knowledge. For Plato true knowledge was demonstrative in its method and confined for its objects to abstract essences: the contents of the world in space and time lacked the kind of reality which was required for knowledge of them to be possible. Descartes went a little further by allowing that there is also knowledge of one’s own current mental states, but he could support the main body of our ordinary convictions only by relying on the principle that a benevolent God, whose existence he claimed to prove, would not deceive us. Hume seemed to himself, and to all of his readers except a group of resolute reinterpreters who take his skepticism to be essentially rhetorical, to have shown that we can know nothing but our own impressions and merely conceptual truths about the relations between our own ideas. Kant, attempting to answer Hume, concluded that we could know the world, but only if it was conceived as largely our own construction; things in themselves being forever beyond our grasp.


There is, however, a body of epistemologists, of the second class, perhaps, by comparison with the great extremists, who lay down altogether less stringent conditions for cognitive salvation: Aristotle, Locke, Reid, John Stuart Mill. These more earnest and responsible figures comment on the methods and results of our common knowledge in a practically more applicable way. The extremists, because of the extravagance of their ideals, can communicate at most a style to the thinking men who are influenced by them. No one, for example, could believe as little as Hume seems to allow, but there is a Humean stand-point of skeptical detachment which has its appeal. Similarly the reorganization of our beliefs that Descartes recommends, in which all our convictions about the common world are rescued only by subordinating them to the veracity of God, is not accepted by all those Frenchmen whose brisk, abstract, uncompromising mode of reasoning displays his influence.

The moderates accommodate their demands more realistically to the human propensity to believe. In Locke our ordinary beliefs are broadly endorsed, even if they show the bruises left by his examination of them, and in Reid the commonsensical dogmas which much philosophy has sought to undermine are sanctified as self-evident truths about the nature of things. It almost seems that the two kinds of philosopher are necessary to each other. The Don Quixotes produce their explosive illuminations; the Sancho Panzas put the pieces together again.

In this century and in the Englishspeaking world, something like this relation obtains between Russell and C. I. Lewis. Russell’s first great achievement was the construction of a purely extensional system of logic. This implied, as Russell eventually came to agree, that logic is not a substantive discipline with a subject matter of its own: it is essentially formal and concerned with the arrangement of substantive discourse about the world, not with making a further addition to such discourse. Lewis’s first books rejected this idea in favor of an intensional logic in which attention is paid not merely to the mathematically manipulable form of our assertions but to the necessary connections of meaning between the terms they contain.

For most of his career Russell was heavily skeptical about memory and induction and confessed in his last major work, Human Knowledge, that scientific theorizing could be ratified only by arbitrary postulations about the world it is applied to. Lewis, on the other hand, gave arguments for the necessary reliability in general of both memory and induction and held that the abyss of doubt that Russell claimed to have detected about everything but what is immediately present to the senses is an illusion.

Finally, despite his strong moral commitments, Russell became convinced that there could be no knowledge in the domain of values and that value judgments expressed personal emotional attitudes and not objective matters of fact. Lewis, in his later writings, fought this widespread opinion with determination, and even ferocity, insisting that our evaluations do express genuine knowledge about the conditions of human satisfaction and suffering.

It is clear to me that Lewis was the most distinguished American professional philosopher of the last halfcentury. The date and the requirement of professionalism rule out Santayana, who left the United States for good in 1914 and was more a critic of culture than a philosopher in the narrow sense. Dewey is Lewis’s most serious competitor. But although he was a much larger figure and has no doubt had more influence than Lewis through his work (most of all in education), as a philosopher pure and simple he is Lewis’s inferior. Despite his rejection of the type of Hegelian idealism in which he was brought up, Dewey retained the edifying amorphousness of its literary and, more to the point, logical style. Lewis, by contrast, is a hard and definite reasoner, although not much more of a stylist than Dewey.

He has now been honored, five years after his death, by the publication of a volume devoted to him in the “Library of Living Philosophers,” the thirteenth person to be so honored. These volumes consist of an autobiography, with more or less intellectual emphasis, by the subject; a series of essays by other people on aspects of his work; and a concluding essay, ideally rather long, in which the subject of the volume answers the criticism in the preceding essays. Three volumes in the series, which has been edited throughout by Professor P. A. Schilpp, are essential philosophical reading: those on Russell, Moore, and Carnap. These philosophers evoked some admirable critical essays and provided thorough and serious answers to criticism. Indeed Carnap’s reply to his critics is the best study of Carnap’s philosophy that there is.


The Lewis volume is not so good as these three major successes. The autobiography, though enjoyable for its revelation of Lewis’s gruff, dour character, is brief and peters out in the middle of Lewis’s career. The essays, although for the most part sound and decent, are generally a little uninspired. The selection of commentators is largely confined to a kind of philosophical Middle America and there are few arresting performers of the kind whose thoughts would be interesting in their own right. Lewis’s reply to his critics is, as he admits, fairly perfunctory. Here, as in other volumes in the series, the subject of the volume was too old by the time the opportunity of commenting at length on his own work came to him to take the best advantage of it. Certainly the next volume announced, which is on Popper, looks more exciting.

The autobiography is interesting about Lewis’s early life. His father worked in a shoe factory and got into difficulties for his membership in the Knights of Labor. The young Lewis was brought up on Fabianism and Bellamy’s Looking Backward and heard and revered Gompers and Debs. He got to and through Harvard only by the skin of his teeth (in 1902 40 percent of Harvard students depended on what they could earn for themselves). By dint of waiting on tables Lewis got his A.B. in three years. By 1912, after various vicissitudes, he had obtained his Ph.D. And so on to the study of Principia Mathematica, the devising of his own alternative logical system, and work in the great chaotic accumulation of the papers of Charles Sanders Peirce.

The characteristic stoicism of his mode of self-description cannot conceal the enormous amount of work he got through in his early years. He picks out Josiah Royce as the teacher who most influenced him but from that point on has little to say about influences, apart from Peirce’s papers. In philosophy, as in life, he was a model of old-fashioned New England self-reliance.

All sides of his work receive full treatment in the essays. A strikingly dull piece on his contributions to the history of logic reminds us that for fifty years his Survey of Symbolic Logic was the best history of logic in English, indeed it was the only serious one until the publication of William and Martha Kneale’s more comprehensive Development of Logic. There is a very thorough and detailed essay on Lewis’s work as a creative logician by W. T. Parry which, by its references to a mass of logical work somewhat at the margin of current interest, draws attention to the considerable influence Lewis has exercised in this area.

Roderick Firth and Roderick Chisholm are good on Lewis’s epistemology. Chisholm has done more than anyone else to develop Lewis’s conception of the theory of knowledge as a normative discipline, an ethics of belief. He points out here that Lewis is a strict moralist in this region: for him there are no indifferent beliefs, any belief that is not justifed ought to be rejected. Firth, with customary exquisiteness, questions Lewis’s assumption that the ultimate foundation of empirical knowledge must be indubitably certain. E. M. Adams neatly points out the uncomfortable relationship, verging on incompatibility, that holds between, on the one hand, Lewis’s empiricist assumptions that the basis of empirical knowledge is subjective appearances and that the meaning of words is determined by the experiences with which they are connected and, on the other, his insistence that his view of our beliefs about material things is a realistic one. Realism implies that there is more to the material world than the appearances it presents to us; but how, on Lewis’s assumptions about meaning and experience, can the belief that this is so be expressed?

Lewis’s work in formal logic has suffered a curious fate. It was undertaken in order to provide an alternative to the system of Principia Mathematica which would accommodate within itself, as that system does not, the essential connectedness that we ordinarily suppose to obtain between the antecedent and the consequent, the if-clause and the then-clause, of a conditional statement. Everyone agrees that “if p then q” is false when p is true and q is false. In Russell’s extensional system that is all there is to “if p then q.” Provided that p is false or q is true, or both, it is true in Russell’s system that if p then q. On this view the truth or falsity of a conditional statement can be established simply by considering the truth or falsity of its constituents. It is not necessary to consider the specific meaning or content of the constituents.

It turns out that this rather meager interpretation of the type of statement that is essential to all reasoning confirms all the rules of inference which we accept in our more reflective moments and which we should want a logical system to preserve, even if it also underwrites as laws certain patterns of inference that are not intuitively acceptable. In particular it is a law of Russell’s logic that if p is false then it follows that if p then q is true, whatever p and q may be and however unrelated they are to each other as regards their content. It also follows that if p then q is true if q is true. whatever p and q may be. These “paradoxes of material implication” impelled Lewis to construct a system which excluded them. But most logicians have accepted them as a reasonable price to pay in oddity for the immense manipulative benefits that accrue from the extensional interpretation of “if—then.” What such an interpretation makes possible is a purely mechanical way of deciding on the logical validity of patterns of inference in which conditional statements occur and on the consistency of sets of statements some of which are conditional.

So, despite Lewis, extensionalism generally prevails in logic. The result may be a bit of a caricature of our ordinary ways of reasoning but it contains what is essential and is vastly fertile from the point of view of formal construction, a liberating simplification. But Lewis’s approach (one should not say “system,” since he devised several, overlapping ones) has not been abandoned. It has found a new employment of an interesting and important kind: as modal logic, concerned with the rules governing the relations of statements containing such words as “must,” “may” and “can,” “necessarily” and “possibly,” “ought” and “oughtn’t.” For example, if p is necessary then p is possible; but if p is not impossible it does not follow that p is necessary. Lewis’s logic has not been accorded the position its creator designed for it, that of representing the rules of ordinary assertion, about what is or is not the case. But a more specialized task has been found for it, that of specifying the rules governing assertions qualified by the pervasive range of modal terms, assertions about what must or should or can be the case.

As an epistemologist Lewis’s position always rested on a fundamental distinction between knowledge that is necessary and a priori, independent of what actually happens in the world, and contingent, empirical knowledge. For Lewis, necessary truth is determined by the relations between the meanings of the terms we use, while all contingent statements must be somehow reducible to the incorrigible deliverances of immediate experience. A full exposition of this logical dualism, which has been fundamental to much of the analytic philosophy of the past forty years, is to be found in Mind and the World-Order (1929), Lewis’s first great book on the theory of knowledge. It anticipated many of the doctrines of the logical positivism of the 1930s but presented them in a more perceptive, perhaps because less polemically combative, way. There is still no better defense of the view that all necessary propositions are analytic than the one to be found in that book.

His account of empirical knowledge received its full development in his long Analysis of Knowledge and Valuation in 1946. It is the culmination of a long tradition of more or less radical empiricism in English-speaking philosophy; prepared for by Locke and Berkeley, salvageable from the skeptical desperation of Hume, set out plainly in outline form by Mill, broken into a number of brilliant, hasty fragments by Russell. Lewis goes at the problem of accounting for our knowledge of, or at any rate justified belief in, a world of material objects existing independently of us, on the basis of the momentary and discontinuous impressions of our senses with a cool head, in great detail, and with a solid readiness to follow the argument wherever it may lead him.

It leads him a long way, into investigations of induction (since our beliefs about the material world are in his view derived by generalizing from the regularities disclosed in our sense experience), probability (since no such belief is ever certain or finally established), and the nature of counterfactual conjectures (since all beliefs about what we are not here and now observing assert, he contends, what we should be observing if certain conditions were to obtain which in fact do not).

The problem of our knowledge of the external world is perhaps more calculated than any other to inspire the non-philosopher with an amused conviction of the essentially dotty and fantastic character of epistemology. This results from incautious formulation of the problem as that of justifying our belief in a world that exists independently of us. As Reid too mildly remarked, that belief “is older and of more authority than any argument of philosophy.” Serious doubt of it is more a sign of mental derangement than of conspicuous intellectual penetration. In fact, the point of the problem is not whether the belief is justified; it is, rather, what the justification actually is.

Lewis’s handling of the complicated network of abstractions involved is an exemplary display of patient and systematic rationality. It amounts to a demonstration that, if the initial presumption that empirical knowledge must have infallibly certain foundations is correct (and, of the large majority of epistemologists who have supposed this, Lewis is almost alone in arguing for it instead of taking it for granted), our belief in a material world must be justified in his way. For it is plain that no beliefs about material objects have the required kind of certainty and such beliefs must, therefore, be inferred from beliefs about private experience which are certain in the required way.

In the last twenty years the theory of empirical knowledge has been considerably transformed by the abandonment of the presumption about empirical knowledge I have mentioned. Various things have contributed to the change. One was G. E. Moore’s persistent efforts to distinguish certainty, properly so called, from the much narrower concept of incorrigibility with which Lewis and those of his persuasion identified it. Another is the recognition that it does not follow from the fact that a belief is less than certain, in either sense, that it must therefore be the outcome of an inference. Since this is so our less precarious beliefs about material things, the ones we should unreflectively regard as direct reports of perception, are fit to serve as the foundations of our knowledge of empirical fact.

Lewis’s reason for thinking that only the certain is uninferred is that probability is always relative to evidence. But that does not, as Lewis thought, entail that all less than certain beliefs must be inferred. Any reason there is for thinking that probability is relative to evidence is a reason for thinking that certainty is relative to evidence too. The type of “direct realism” propounded by many current theorists of perception sees no logical difficulty in the admission that fallible beliefs about material things can be direct and uninferred reports of our perceptions just as well as the infallible beliefs about sense impressions which theorists of knowledge from Descartes to Lewis have held to be the only possible occupants of this epistemologically basic status.

The main preoccupation of the last twenty years of Lewis’s philosophical career was ethics, in a wide sense of the term that embraces prudence as well as morality, indeed, the whole range of principles by which conduct can be rationally guided. This width of scope, in which prudence, as the reflective pursuit of private advantage in the long run, as well as morality with its impersonal ends, is contrasted with the solicitations of immediate desire, marks him off from the majority of recent ethical philosophers by whom morality is considered in an unearthly isolation while all other action-guiding factors, whether rational or not, are indiscriminately lumped together. Lewis’s approach draws attention, to the fact that morality is not the only or most representative way in which conduct may be rationally guided. The conflicts with which it abounds tend to suggest that evaluation in general is an altogether more chaotic and emotional affair than it is.

Lewis’s first publication on ethics was Book III of his Analysis of Knowledge and Valuation. Eighty-thousand words long, it could have been a substantive work on its own. In it he treated valuation in general, without distorting concentration on moral valuation, in a way that should have been exemplary, but unfortunately was not. In 1955 he published his Woodbridge lectures, The Ground and Nature of the Right, in which morality proper is approached more closely but still in a fairly gingerly way. Now John Lange has edited a collection of Lewis’s pieces on ethics written between 1948 and 1959 under the title Values and Imperatives.

It is an attractively produced and altogether useful volume, understandably a bit repetitive, rendered delightful for connoisseurs of the idiosyncrasies of Lewis’s style by a fine array of characteristic touches. As the years went by Lewis’s manner of utterance became ever more gnarled and stilted. But although it became an increasingly graceless vehicle of thought, it remained entirely serviceable. A consistent peculiarity is abstention from articles: “a” and “the” are rigidly excluded from many places where they might have been expected. “Solution of this problem is hard to find,” he will say, or “this doctrine must be subjected to critique of cogency.” Much of his vocabulary is heavily upholstered: words like “purview,” “pertinent,” “perchance,” “venture,” “gratifying,” “cognize,” to offer a random sample, remains of the language of late nineteenth-century protestant edification. Finally, he had a fondness for the subjunctive: “if it be that…” and “it were well that….”

That this rather elaborate diction only grew on Lewis with time is made clear by the magnificent and magnificent looking assemblage of the Collected Papers of C. I. Lewis which has been brought together under the editorship of John Goheen and John Mothershead of Stanford University. This noble volume contains thirty-five of Lewis’s essays, written between 1912 and 1957, divided up into groups of criticism, ethics, epistemology, and logic. A number have not been published before but also here are some of the most influential and best known philosophical pieces of the last half-century (a fact attested to by the frequency with which they have appeared in anthologies) such as “Experience and Meaning,” “Logic and the Mental,” and “The Modes of Meaning.”

Some excellent published pieces of earlier date have been rescued from comparative neglect, such as his fine “Facts, Systems and the Unity of the World,” a logician’s critique of idealist metaphysics. The style of the earlier pieces is much more straightforward than that of his later works. A splendidly cool and authoritative dismissal, written in 1917, of the popular thesis that German idealism was responsible for the 1914 war makes its point with none of the cumbrousness and grandiloquence of his better known prose.

Lewis’s chief concern in ethics was to resist what he saw as the destructively sophistical agreement among up-to-date philosophers that judgments of value are neither true nor false and that they express not knowledge but only emotion. His positive view was that there are objective values and that they are unmysteriously empirical. We have a personal, subjective awareness of value in the satisfyingness or displeasingness that we find to be as much a feature of our immediate experience as shape or color. He saw the relation of objective value to experienced satisfaction as paralleling that between the real shape or color of things and the shape or color they appear to have. For a thing or situation to have objective value is for it to have the capacity to yield satisfaction for people in general in ordinary circumstances. There can be illusions of valuation, just as there can be illusions of perception, but they can be identified, as illusions of perception are, by their incongruity with the general testimony of individual experience.

Rightness and wrongness, for Lewis, are properties of actions that are within our control and they are determined by the value of the consequences to which those actions lead. It is important for the critical side of his argument that the terms “right” and “wrong” should be widely applicable, not merely to actions being morally appraised, nor just to actions involving bodily movements, but also to “internal actions” of believing and inferring. For it confronts those who would deny objective validity to judgments of moral rightness with the possibility that the same denial should be extended to the assumptions of logical rightness on which their arguments depend.

He distinguishes four main fields in which judgments of rightness and wrongness are made: prudence, where the end is a comprehensively satisfactory life for the agent; morality, where the end is justly distributed satisfaction for all; logic, where it is the consistency without which there can be no rational thought or significant speech; and epistemology, where it is cogency or a reasonable prospect of truth. In each of these domains there is a generally valued end, conduciveness to which sets the standard of right for that domain. If ethics, in the widest sense, is the theory of right action, including thought, then, he argued, it disastrously undermines itself if it holds judgments of rightness to be subjective. This for Lewis is an aberration which philosophers have been led into by concentrating on moral rightness alone to the neglect of other kinds of rightness.

The liveliest aspect of the essays in Values and Imperatives is Lewis’s vigorous development of this theme against the prevailing “non-cognitivist” orthodoxy in moral philosophy: the idea that value, or moral value at any rate, is not a possible topic of knowledge. He thought it absurd to suppose that the dictates of prudence are not rationally discoverable matters of empirical fact and, since that is so, why should not the same be true of morality? Against the idea that principles of obligation are matters of arbitrary choice he argued that this makes subjective nonsense of the imperatives of logic and epistemology. He often recurs to the pragmatically selfcontradictory character of the Cyrenaic’s rejection of prudence. The resolution to take no thought for tomorrow is self-refuting since it is itself a thought for tomorrow as well as for today.

In broad outline Lewis’s position is close to that of Bentham’s utilitarianism, for which the ultimate standard of value is the greatest possible pleasure for all, but it is wider in scope. Lewis did not deny the affinity but laid stress on some points of disagreement. He rejected “pleasure” as an adequate description of the positively valuable and expressed doubts about Bentham’s notion of a calculus of value with its suggestion that problems about the comparison and balancing-off of the pleasures and pains of different people could be settled in a simple, mechanical way.

In the best essay on Lewis’s ethics in the Schilpp volume, Mary Mothershill points out that he makes rather too much of this disagreement with Bentham’s idea of a calculus. He certainly allows for the comparison and over-all estimation of the values and disvalues realized for different people in the consequences of a particular action. But, as she goes on to show, there is a substantive difference with Bentham in the special emphasis Lewis lays on the satisfactions that come from activity as constitutive of a good life, in contrast to merely passive enjoyment.

For all its elaboration there are several loose ends in Lewis’s theory of value. Robert W. Browning points out in a perceptive essay that Lewis does not really address himself to the fact that the value experiences that things give rise to vary much more from one person to another than do the sense experiences they produce. A more homogeneous conception of human nature than the facts warrant seems to be presupposed by the idea that an objective, social, impersonal value can be ascribed to things in the way that perceptible qualities like color can be ascribed to them. Our tastes are more various than our sensory equipment. In particular, the expert or connoisseur has a place in evaluation that the does not have in ordinary perception. No expert is needed to tell us that The Golden Bowl is long and written in English, nor is there any persisting doubt about these judgments. But this is not obviously true of the book’s value. It is not hard to think of the sort of modifications Lewis’s theory would need to meet this kind of objection, but the modifications are needed.

Another important weakness is the very tentative nature of Lewis’s engagement with morality proper. To start with he offers two definitions of the domain of the moral that do not coincide. On the one hand, it is tied up with justice or consideration for others; on the other, it is identified with the resultant or over-all value of an act or state of affairs when all particular value-claims have been taken into account. To regard these as the same is to make altruistic self-suppression the ultimate rule of conduct by implying that in every situation of choice consideration for others must override all other claims.

In general there is something of a gap between the well-worked-out view that values are matters of empirical knowledge and the conception of the morally right as that which contributes most to the satisfaction of all. We all may agree that it is right to change out of wet clothes and come to this agreement by the same train of reasoning and in the light of a universally shared hostility to pneumonia. There is no such community of reasoning or of attitude toward the taking of human life to sustain an objective judgment about the moral acceptability of euthanasia.

Lewis shows an awareness of this gap by endorsing a description once given of him as a naturalist with respect to the good but a rationalist with respect to the right. This is a somewhat confusing way of recognizing his need to connect the idea that each man’s satisfaction is a good to him with the idea that the general satisfaction is a good to all. What he offers as a connecting link is the fact that we are social beings. “The ground of our obligation to another person,” he writes, “is that we know him to be as real as we are, and his joys and sorrows to have the same quality as our own.” As it stands this goes no further than, if it goes as far as, Hume’s grounding of benevolence in instinctive sympathy, an interest in social peace, and the convenience of having the same rules for all.

It is a measure of Lewis’s influence that, despite the somewhat old-fashioned quality of his style and approach, he is very much a background presence in two ambitious and resolutely up-to-date books by young American philosophers. In Arthur Danto’s Analytical Philosophy of Knowledge, indeed, he is very much in the foreground, being, along with Austin, the most frequently mentioned twentieth-century philosopher in the book. There is only one explicit mention of him in Thomas Nagel’s The Possibility of Altruism. But Nagel’s project, which is to show that morality, the consideration of the welfare of others, can be shown to be rational in just the same way as prudence, the consideration of the welfare of one’s future self, is entirely Lewisian.

Danto’s book has been unfavorably criticized for its convoluted and ornamental style. It is written with the kind of showy and nervous volubility that suggests a lack of self-confidence. Danto insistently applies the symptomatic word “banal” to positions from which he is anxious to dissociate himself, as if in terror of the raised eyebrows of some group of arbiters of philosophical chic. I said earlier that Lewis’s style was quaint and clumsy, but its peculiarities do not obstruct understanding or slow up the argument. This cannot be said of Danto’s. Where Lewis advances on his readers in dun-colored verbal garments of complex and antiquated cut, which nevertheless do not impede his movements, Danto keeps falling over the elaborately unfunctional folds and hanging of his stylistic fancy dress. (Nagel, however, appears in a tight-fitting scuba-diving rig, in which he moves so rapidly that it is often hard to keep up with him.)

Danto’s main thesis is that epistemology is concerned with “the space between language and the world,” that is to say with a group of semantic concepts the chief of which are knowledge, truth, and existence. These concepts do not describe ordinary empirical properties of the thoughts and things to which they are ascribed but, rather, the semantic relations of thoughts, sentences, and the names of things to the world. The type of very general and far-reaching skepticism that has always provoked epistemological reflection dramatizes the gap between our thoughts and the world they refer to by insisting that we are irrevocably stuck on one side of the gap.

Danto holds that the gap is necessary and so is not a ground for skeptical anxiety. His all-purpose cure for doubt is the principle that in order to understand a sentence one must be able to experience whatever it is in the world that makes it true. The possibility of knowledge necessarily follows from the fact of understanding. Without understanding there is nothing about which the question of knowledge can be raised.

On the way to this conclusion Danto disposes, to more or less effect, of various competing accounts of the nature of knowledge; of the idea that true knowledge must be infallible (making very heavy weather of what is at most a partial diagnosis of this assumption); and, more convincingly, of the idea that to know something is to know that one knows it. He accepts the traditional distinction between direct knowledge based on experience and indirect knowledge that is derived from other knowledge already possessed. By laying down the very strong condition that indirect knowledge must be logically entailed by the evidence for it (the usual view is that the evidence for it should be good or sufficient, not logically conclusive) he avoids consideration of the whole topic of justified, as contrasted with absolutely certified, belief which ordinarily forms a main part of epistemological discussion.

His main point, perhaps, is that experience has been traditionally misrepresented as the object of knowledge, when it is in fact the relation between the knower and the world he knows. Traditional theories (Lewis’s as much as Descartes’s) maintain that the only direct objects of knowledge are experiences themselves, namely private ideas or sense impressions. Danto concludes from the fact that sentences about public, extra-mental objects are intelligible that such things can be experienced directly. The traditional view that public, material things can be known only indirectly is nowhere, as far as I can see, refuted, although I agree with Danto that it is in fact false.

Nagel’s The Possibility of Altruism is an extremely tough, polished, and altogether stimulating piece of work. Most recent ethical theorists, by their monocular concentration on the issue of the precise logical status of moral judgments (are they really statements, true or false; are they implicitly universal?) have taken it as a simple brute fact that people are disposed to make such judgments and to guide their conduct by them. Nagel, adopting the sensible but recently much blown-upon position that the core of morality is concern for the welfare of others, raises the grand old question: why should I be moral, how can it be shown to be rational to pay any attention to the welfare of others except to the extent that doing so can be seen to conduce to my own well-being?

His basic strategy is much the same as Lewis’s. If men are conceived as always choosing simply between what morality dictates and the satisfaction of their own desires, their choice of the former is made to look irrationally self-immolating. But such a view, he holds, misrepresents the nature of our situations of choice. In the many situations where no moral considerations are relevant we still have to choose ordinarily between what our present desires suggest and the requirements of prudence, which takes into account the desires we have good reason to think we shall have in the future.

The heart of his argument is that the desires relating to the future which prudence takes into account are not desires we currently possess. To cater for them by taking out insurance, giving up smoking, stifling rude remarks is only rational in the light of the fact that we are beings that endure or persist through time. For most people most of the time it is true that they have a future in which chickens will come home to roost and the displeasing consequences of present gratifications will materialize. One attitude toward conduct that everyone would admit to be irrational is that it is the kind of impulsive living in the present that is uninfluenced by the fact, that we are temporally continuing beings.

The next step Nagel takes is to argue that there is another fact, parallel to that of our having futures, which makes a measure of altruism rational (he is not arguing for major self-sacrifice, only for consideration for others) in the way that our futures rationalize prudence. Just as the desires we actually have, rather than have reason to think we shall have, are insufficient to justify prudent conduct, he says, so our natural benevolence and our personal interest in being members of a peaceful and not vengefully disposed society are too weak to justify the kind of consistent and principled concern for others which constitutes the minimum demand of morality. The elementary fact which, according to Nagel, makes it rational to be concerned with the satisfactions and sufferings of others is that they really exist and do rejoice and suffer in just the same way as we do.

Many ethical theorists have been dissatisfied with the attempt to base morality on its connection to our private, personal interests. Our natural benevolence, as Hume observed, is fairly confined in its operations, largely to the small circle of people whom we love or are fond of. It is, of course, personally convenient to each of us that morality should be maintained as a general institution, but we can easily argue that a few tempting deviations from its requirements can be indulged without damaging it perceptibly, provided that they are carefully concealed and so do not evoke vengeance or inspire imitation. Something more seems needed to justify a fixed and settled practice of altruism, and Nagel finds it in recognition of the fact of the real existence of others.

If I found the parallel argument that our really current desires are too weak to justify prudence both cryptic and elusive it may be because it is a genuinely new and original idea. He does seem to me to have overstated the case in saying that we have in fact very few desires for anything but the immediate future. I now strongly desire many things which I should like to have now if it were possible but which I know I shall have to plan and work for in a protracted way. He could still say, however, that I do not currently desire to be solvent and healthy in twenty years’ time (and much of my prudent behavior is directed toward that end) but only know that I shall desire it when the time comes.

There is a more fundamental weakness, I think, in the parallel he draws between the fact of my future existence and the real existence of others. He says that the concern for others that expresses our recognition of their equal reality with ourselves does not need to be understood as any kind of “mystic identification” with them. The recognition that there are other people is, after all, a recognition that they are other people. But although in conceding the reality of other people I am certainly not taking myself to be in some way actually identical with them, as contrasted with being more or less like them in certain respects. I surely am the very same person as my future self, I am numerically identical with that future being for all our differences with regard to teeth, hair, posture, and general vivacity. The desires for whose satisfaction I cater in my prudent conduct are still my desires, even if they are not my desires yet. The desires of others that I aim to satisfy with my moral conduct are not, and never will be.

But despite these doubts Nagel’s attempt to strengthen a weak link in Lewis’s ethics seems to me more successful, at least to the extent of deserving a good deal of further and serious examination, than Danto’s attempt to circumvent the main problems of his epistemology altogether.

This Issue

July 23, 1970