In this paper I intend to do two things. The first is to discuss a method of doing philosophy, the method of ‘ordinary language’ philosophy, as it is commonly and misleadingly called. (Its other common title: ‘Oxford Philosophy’ is even more misleading, since the roots of the method lie in Cambridge, and many of the most flourishing branches are in the United States rather than England.)If it needs a name, perhaps the best is—adapting Popper to our purpose—‘piecemeal philosophical engineering’. Such a title would emphasise the attention to detail and the caution about conclusions that characterise the best of such work. The second aim of this paper is to apply the method thus discussed and defended to three questions connected with the concept of freedom. These problems arise out of three recent discussions of freedom—Thought and Action and Spinoza and the Idea of Freedom by Professor Hampshire, and Two Concepts of Liberty by Professor Berlin.

By all indications, the popularity of the Sense-Datum Theory is definitely on the wane. This once-proud theory, which was perhaps the most characteristic feature of British Philosophy during the first half of this century, has been attacked from so many different sides that even its foremost protagonists have either accepted the very watered-down version according to which it is just an alternative language for speaking about the facts of perception or else they hold their peace and let the youngsters play. There are still some diehards who carry on as if nothing had happened, but they are an insignificant minority.

Traditional definitions of determinism in terms of causation seem nowadays to have been largely superseded by accounts in terms of predictability. If it were true that all and only caused events were predictable then doctrines of universal causation and universal predictability would be equivalent and it would only remain to ask what advantages if any an indirect epistemological account had over a direct ontological one—none, one might have thought, more especially if the former presupposed the latter. In fact, however, the two are by no means so simply and directly related: being caused is neither alone sufficient nor yet again is it necessary for predictability, or so at least I shall be endeavouring here to show.

The Term ‘liberty’ invokes such universal respect that most modern political economists and moralists endeavour to find a conspicuous place for it somewhere in their systems or prescriptions. But in view of the innumerable senses of this term an insistence on some kind of definition prior to any discussion seems to be justified. For our present purposes attention to two particularly conflicting interpretations will be sufficient. These are sometimes called the ‘negative’ and the ‘positive’ notions of Liberty. According to the ‘negative’ notion, my own liberty implies the reduction to a minimum of the deliberate interference of other human beings within the area in which I wish to act. Conversely the absence of liberty, or coercion, is regarded as undesirable because it amounts to the prevention by other persons of my doing what I want. On the other hand, the ‘positive’ sense of the word ‘liberty’ consists in the attainment of self-mastery, or, in other words, the release from the domination of ‘adverse’ influences. This ‘slavery’ from which men ‘liberate’ themselves is variously described to include slavery to ‘nature’, to ‘unbridled passions’, to ‘irrational impulses’, or simply slavery to one's ‘lower nature’. ‘Positive’ liberty is then identified with ‘self-realisation’ or an awakening into a conscious state of rationality. The fact that it is contended that such a state can often be attained only by the interference of other ‘rational’ persons who ‘liberate’ their fellow beings from their ‘irrationality’, brings this interpretation of liberty into open and striking conflict with liberty in the ‘negative’ sense.