However, as Bertrand Russell (1872-1970) wrote:“the merit of the Copernican hypothesis is not truth, but simplicity.”105 This simplicity reveals itself as a simple scrutiny of facts and premisses, and subsequent rejection of superfluous hypothesis - a method commonly called Occam’s razor. It was this relative freedom from authorities that won Kant’s approval, for according to Kant it was the method through which Copernicus reached a solution that was the real novelty, insofar as Copernicus let the subject (the astronomer) disregard the previous methods of only letting the conclusions be uncritically dictated by those things that were accessible to the observer, be they facts or authorities. Instead, Copernicus allowed the observer to elevate and shift the perspective from the directly empirically accessible (the geocentric world view) to the rationally accessible (the heliocentric world view), whose validity, if not truth, could be tested by rational means. In other words, by temporarily disregarding facts, the observer through a subjective, but formal and systematic rearrangement of facts could arrive at conclusions explaining reality and causal relations better than could passive observation.According to Kant, the overriding goal of such intellectual operations was to arrive at that which sensory observations alone could not determine, namely synthetic knowledge a priori. Furthermore, by rationally testing the validity of his hypothesis Copernicus actually managed to provide a (relatively) consistent explanation for the observed astronomical phenomena (such as, for instance, the perceived retrograde action of planetary movement). Even though Copernican cosmology is only a rationally accessible explanation, thus lacking material truth value, it at least provides the scientist with the necessary tool to test the validity of competing hypotheses, namely consistency and simplicity. According to Kant, the Ptolemaic explanation’s fault is that it relied solely on sensory data and uncritically adduced authorities, which is the direct cause of the problems afflicting the astronoa ca l l f o r s c i e n t i f i c p u r i t y 67 105 Ibid., p. 225.