This paper is concerned with a problem which has puzzled me for many years. The Greek philosophers of the Ionian tradition, from Anaximander to Epicurus, are commonly called specially ‘scientific,’ in contrast with the Italian tradition started by Pythagoras. Why is it, then, that their systems are cast in the form of dogmatic pronouncements? It is not only that they describe, with complete confidence, matters beyond the reach of observation, such as the origin of the world; but when they come to matters of detail, they make assertions which could have been upset by a little careful observation or by the simplest experiment.

It has been argued—by Burnet, for instance—that this dogmatism may be only apparent. Our evidence is fragmentary, and comes largely from manuals compiled much later by men whose object was to discredit science for reaching contradictory conclusions, and by no means to record the methods employed to reach those conclusions. W. A. Heidel, too, thought that, if we possessed the philosophers' notebooks, we should find that their results were obtained by methods akin to those of modern science, though with less awareness of the need for caution in experimental tests. Behind these arguments lies the assumption that the questions they asked themselves, the motives prompting their inquiries, and the quarter to which they looked for the sources of knowledge, were the same then as now.