If one man were to be singled out as personifying Oxford analytic philosophy over the past thirty years, Sir Peter would be that person. In these four lectures, which he delivered at Columbia University in 1983, he weighs issues in four traditional arenas of philosophical contention. In one arena the existence of external objects is at stake, in another the grounds of morality, in a third the status of mentalistic language, and in a fourth the existence of abstract objects.

Skeptics have long challenged our evidence for the existence of external objects. In response Strawson toys first with a “transcendental argument,’ somewhat reminiscent of Kant, which purports to show that our very ability to entertain the question of the existence of external objects presupposes our belief in them. Dissatisfied, he rallies to the naturalism, as he calls it, of Hume and Wittgenstein. Their position is that belief in external objects is ingrained in human nature and is never really suspended, the skeptic’s pretensions notwithstanding. It is not open to doubt or, therefore, to substantiation.

If this dismissal of the problem is felt to be lame, I would suggest that the feeling can be relieved by taking a more fully naturalistic stance. Our words have no meaning beyond what they acquire through our learning of them, and all our learning of them goes back directly or indirectly to the association of utterances with concurrent sensory stimulation. The sentences of science, no matter how theoretical, acquire what meaning they have through a network of sentence-to-sentence links whose starting point is sensory stimulation. All evidence for the truth of a scientific theory, moreover, is drawn from sensory observation through that same network. The existence of external objects is itself just one among the tenets of our scientific theory, albeit a primordial one, and it is sustained to the degree that the theory as a whole conforms to observational data. The very meaning of the existence thesis lies no deeper.

The skeptic who challenges the existence of external objects, in that first arena, has in the moral arena a confederate who challenges the objectivity of moral judgments. Strawson seems to suggest that this challenge would be met if we could show that human action is not ultimately determined by external causes. This connection is not clear to me, but no matter, for Strawson recognizes that “no one has been able to state intelligibly what such a condition of freedom…would actually consist in.” Tentatively he opts rather, as in the first arena, for the strategy of what he calls naturalism: human nature is inescapably committed to moral values, and there is no scope for challenge or defense.

He distinguishes between this brand of naturalism, which he calls “liberal,” and another which he calls “reductive.” In dealing with the moral matter the reductive naturalist is at one, it seems, with the skeptic. Strawson is responsive to the claims of both the liberal and the reductive naturalist with regard to morality, and he seeks to reconcile them by adopting a relativistic position. From the standpoint of participation and involvement, moral values are real; from an external standpoint they are just behavioral data for the annals of the anthropologist. Strawson draws an analogy in perception: from the percipient’s standpoint a table is smooth and hard, but from an objective standpoint it is a seething multitude of particles.

I see no need of contrasting standpoints in the case of the table. The molecular physicist can agree with the percipient that the table is smooth and hard; he just goes on to provide the surprising microphysical detail of what constitutes smoothness and hardness. He reveals the fine structure. This way of relating the physicist to the percipient restores a welcome unity of outlook.

And what then of morals? We can say with the reductive naturalist that moral law has no objective support in nature, being merely a pattern of human response and behavior rooted in natural selection and moral training; but we can still accept it for what it is, and as human beings among other human beings we can continue to espouse it and conform to it. The purported difference between reductive and liberal naturalism, in these contexts anyway, looks verbal.

In the third arena, which features the confrontation of mind and body, Strawson opens the proceedings by dismissing, as most of us do nowadays, the dualistic view of mind and body as distinct substances. It is the physical person, rather, that satisfies mental and physical descriptions; and what is in question is just the relation between these two sorts of descriptions. Each single, dated mental event or state is an event or state of the body and could in principle be described exhaustively, Strawson grants, in physiological language. However, the words we use to describe mental events or states—“mental predicates”—are general, like any predicate; each is fulfilled by any number of individual events or states. The same is true of the physiological predicates, and it is between the groupings imposed by the two sorts of predicates that the incommensurability between the mental and the physical subsists. Such is Strawson’s view, if I interpret him right, and it is shared by Donald Davidson and, I like to think, many others. Strawson demurs still over the “identity thesis,” which identifies mental states and events flatly with physical states and events; but what is at stake here seems to be just a question of phrasing.


The opposition between reductive and liberal naturalism reappears in this third arena, according to Strawson, as a contrast between physical and personal histories—the latter being couched in mentalistic terms of motives, purposes, desires, beliefs, and the like. Here again the notion of an opposition between two parties—between “the tough-minded and the tender-minded,” in William James’s phrase—strikes me as unfortunate. Anyone, however tough his mind, is well advised to recognize both the irreducibility and the indispensability of personal history and the mentalistic idiom. And the tender-minded person, conversely, if not too tender for “liberal naturalism,” is well advised to recognize the business of theoretical physics and astronomy as the exploration of the uttermost principles and mechanisms of nature. This is not to say that even physiology or entomology, let alone economics or personal history, is translatable into terms of electrons, quarks, spin, charm, weak force, gravitation, and the rest of the theoretical physicist’s austere lexicon. Who would reduce Gresham’s law to quantum mechanics? Once more, as in the morality arena, the opposition of reductive and liberal naturalism seems to waver and dissolve.

A final joust between the reductive and the liberal naturalist is staged in the arena of ontology, the study of what there is. Strawson represents the reductive naturalist at first as repudiating abstract objects of “intensional” kind, by which he means thoughts, ideas, propositions, properties, as opposed to natural objects. But presently he has him repudiating abstract objects of all sorts, including numbers, functions, classes.

The merits of the two cases are very unlike, and Strawson ought to have distinguished and contrasted them. There are reasons for shunning intensional objects, quite apart from any reductive proclivities. A major reason is that it is not clear when to say of two sentences that they express the same proposition, or when to say of two conditions that they determine the same property and not just two coextensive properties. As a means of settling such questions, philosophers have been led to invoke a notion of metaphysical necessity according to which two properties are the same insofar as they are “necessarily” equivalent (like the properties of “bachelor” and “unmarried man”); and for this, again, no clear criterion is evident. Moreover, none of these troublesome intensional objects seems to be needed for a scientific account of nature.

Intensional or mentalistic locutions have their place still in personal history, and we are already agreed that personal history is an indispensable mode of discourse. Ontological questions, however, are best seen as questions not of personal history but of the realities of nature; and in the scientific mode of discourse appropriate to those realities the existence of intensional objects may justly be denied.

Numbers, functions, and classes, on the other hand, for all their abstractness, are not to be lightly dismissed even from the scientific system of the world. Numbers are referred to as abundantly in the laws of physics as are forces or particles. It is not just a matter of the use of numerals, which might or might not be viewed as naming; it is a matter of wholesale reference to numbers as the objects denoted by general terms and pronouns and as the values of variables in scientific statements couched in mathematical language.

Even in what seems to be down-to-earth and ontologically uncommitted talk about words, moreover, as Strawson remarks, we talk mostly not of individual cases of a sentence being spoken or uttered, but of sentence types, which at the very least are classes of inscriptions or utterances. Even when we speak of a sentence like “The sun is hot,” we can say we are referring to the class of all the instances of the sentence—written, spoken, printed, engraved, etc. However enticing to the tough mind, nominalistic repudiation of all abstract objects is simply incompatible with all levels of science as we know it. Intensional objects can indeed be banished, and good riddance; but the extensional abstract objects, numbers notably, remain to be reckoned with (and that not in one sense alone). If Strawson’s reductive naturalist shuns all abstract objects while still championing science, then he owes Strawson and the rest of us an account of what he means by the unreality of objects that he is still seemingly making full use of. If he merely means that they are not in space and time, he can count on agreement from liberal naturalists and even tenderer minds. On this point I find Strawson underestimating the strength of his own position.


This Issue

February 14, 1985