Even the social scientist who is occupied with the study of what are called institutions must draw his ultimate data (with one important exception mentioned below) from the experience of the senses. Suppose, for instance, that he is engaged on a study of the role of trade unions in contemporary England. The abstract conception 'trade union' is simply a shorthand for certain types of behaviour by certain people, of which we can only be aware by sensory perception. It means men sitting in a room and making certain sounds in the conduct of a 'trade union meeting', or handing over to other persons tangible objects (money) as their subscriptions to the union. Anyone who wishes to make a study of trade unions, or even of the more abstract conception 'trade unionism', can only do so by personally observing such behaviour, or by using his eyes and ears on books and speeches made by other people who have themselves made such observations (or who have in their turn heard or seen records of such observations made by others). Even such comments on a union meeting as that it was 'orderly' or 'peaceful' are fundamentally statements about its physical properties: an orderly meeting is presumably one in which people do not make noises by banging upon the table or speaking very loudly.

This dependence of social studies upon sense perception is certainly a wholesome reminder of the fundamental homogeneity of the original data of science. For knowledge of the external world, whether of things or of people, we continually come back to our five senses in the end. Nevertheless, if a great mass of data relevant to social science is sensory, we have, I think, also to admit an important collection that is not namely the whole body of primary mental or psychological experience. Perception of mental pleasure and pain appears to have the same universality as sensory experience. At all levels of culture, sensations of simple happiness and unhappiness are as general as are the experiences of seeing and hearing. It is of course true that no person can experience the feelings of anyone other than himself; but equally no one can see with another's eyes or hear with another's ears. The grounds for belief in the sense experiences of other people and the grounds for belief in their primitive psychological experiences are thus both equally shaky, or equally firm. We derive our conviction that other people experience emotion from the fact that they say so, and from analogies between their behaviour and our own: we derive our conviction that they see and hear from exactly the same evidence.

The irresistibility of psychological experience is perhaps slightly more disputable. If one's eyes are open and one looks in a certain quarter one cannot help seeing. Is it equally true that one cannot help a feeling of pleasure or pain or shock or excitement? Essentially, I should say that it is. But it is clear that primitive emotional reactions can be inhibited: one can, for example contrive not to be depressed by an event. Nevertheless, if we stand back from all philosophical niceties and ask ourselves whether psychological sensation ought to be omitted from the data of the social sciences on the ground that it is doubtfully 'primitive', there cannot, I think, be much doubt about the answer. We must conclude with Bertrand Russell 'that there is knowledge of private data, and there is no reason why there should not be a science of them'. Equally, if we consider whether the similarities or the differences, in this matter of universality-plus-irresistibility, between psychological and sensory experience are the more impressive, we are surely bound to come down on the side of the similarities. Certainly, social studies which consistently ignored human feelings would be worse than laughable.

(From Testament for Social Science by Barbara Wootton)