We think that, at the present stage of man’s evolution, science is the one activity in which he displays himself as a truly rational creature. The reason is, of course, that success is granted on no other terms; in everything else, philosophy, theology, politics, reason is usually the handmaid to prejudice. The penalties that visit error in these fields are not so swift nor so unambiguous. The ideal of truthfulness is probably more rigorous with the scientist, _qua_ scientist, than with any other kind of man. But it would appear that this dispassionate rationality is hardly won and precariously maintained. Outside his laboratory the scientist may, and usually does, show himself as simple, as kindly, as credulous, as irrational as any other man. On Bolshevism, Disestablishment, the Morality of the Public Parks, his opinions will be indistinguishable from those of any other comfortable member of the lower middle class; that is to say that opinions on all such matters are “distributed” amongst scientific men according to the same statistical rules as they are distributed amongst ordinary citizens. Outside their views on purely scientific matters there is nothing _characteristic_ of men of science. The Royal Society may conceivably issue a unanimous report on some scientific matter; it would issue a unanimous report on nothing else whatever. Now on the assumption that men of science are truly rational beings this is a very strange state of affairs. Dispassionate attempts to sift evidence, to argue correctly and to base judgments solely on the outcome of these processes could hardly result in so remarkable a multiplicity of opinions. We must assume that, for scientific men as a body, their “scientific” methods of thought function only within very narrow limits. As a distinct community they are far less coherent than, for instance, the community of artists--musicians, poets, painters. The community of artists, with the exception of a few prosperous members, exhibits a really remarkable homogeneity in matters outside art. Doubtless this homogeneity is based on feeling--unless we are prepared to admit that artists, as a whole, are more rational than are men of science--and it is probable that the scientist’s difference from his fellow-citizens is more an intellectual than an emotional difference. But it is surprising that greater emotional sensitiveness should prove so much more pervasive and dominating a peculiarity than greater intellectual subtlety.