One of the most striking and significant features of the present climate of opinion is to be found in the resumption, often tentative, questioning but real, of the age-old conversation between philosophy and theology. It is not to the present purpose to trace in detail the reasons which led to the lapse of this conversation in the first instance; but it would probably not be misleading to lay very considerable weight in this connexion upon two developments in modern thought, one in the sphere of philosophy and the other in that of theology.

The former of these consists in the rise of the school of radical empiricism or logical positivism, and especially in the enunciation of the principle of empirical verifiability according to which the test which determines whether an alleged statement purporting to be informative and not just tautologous or analytic is really meaningful or not is that it should be in principle empirically verifiable or falsifiable, in other words, that there should be the possibility of certain observations in sense-experience relevant to its truth or falsity. It is now some thirty years since Professor A. J. Ayer announced the elimination of metaphysics on the ground that ‘no statement which refers to a “reality” transcending the limits of all possible sense-experience can possibly have any literal significance’, so that ‘the labours of those who have striven to describe such a reality have all been devoted to the production of nonsense’ and Professor Ayer was no less emphatic, when he turned his attention to theology, that ‘the possibility of religious knowledge’ had ‘already been ruled out by our treatment of metaphysics’.