  Clearly, with this reference to the connection between science and disproof, Bondi has added a distinctly Poppererian element to the deductivist methodology, one which had not previously appeared in the works of any of the earlier members of the hypothetico-deductive school. According to Popper’s philosophy of science, a theory can legitimately be called “scientific” only if that theory makes a prediction that, in principle, can be shown to be false, or falsified, to use Popper’s own term. Thus astrology, for example, fails to be a scientific theory because it cannot be falsified: although astrology seems to make predictions, these statements about the future are so vague, so general and abstract, that they cannot be tied down to definite claims about observations to be made at a definite time and place. Hence there is no explicit observation to be made in falsification. Astronomy, in comparison, makes explicit, specific predictions about what will occur in the sky on such-and-such a date, in such-and-such a place. If the prediction fails, then we know that the element of astronomical theory which made the prediction is deficient, maybe even false.