The Closing of the Western Mind: The Rise of Faith and the Fall of Reason by Charles Freeman Read Free Book Online

rock. So perhaps it was some kind of animal. Yet it could not live detached from a rock, as an animal would. Jellyfish, on the other hand, lived as detached organisms but did not, so far as Aristotle could see, have any perception. They are like plants but, unlike other plants, do not stay attached to a base. Should one create a separate category, “plants which are detached,” or does one accept that it is possible to be an animal without having perception? Aristotle’s genius lay in realizing that these issues had to be worked out undogmatically, that observation had to continue and that sometimes the boundaries between categories would have to be redrawn as a result. In the natural world one could seldom, perhaps never, talk with absolute certainty in the face of the mass of living organisms that had to be categorized. It was this openness to the provisional nature of knowledge that helps make Aristotle one of the truly great philosophers. 20
    Aristotle also firmly believed that knowledge would be cumulative from generation to generation, and this process was supported by the competitive nature of Greek science. Take, for example, the idea of spontaneous generation. Aristotle first posited the concept after he had tried in vain to find out how eels spawned. He could find elvers, young eels, but no sign of what they grew from. The answer was straightforward if remarkable—eels spawned in the Bermudas and the young swam back to Europe—but, of course, this was well beyond any possibility of discovery in the fourth century B.C. The act of spawning was not observed for the first time until the 1920s. So the idea of spontaneous generation, from mud in the case of eels, was one possibility. Aristotle’s successor Theophrastus took the matter further. He examined many different cases of apparent spontaneous generation in plants and showed that, in fact, there were often tiny seeds from which plants grew. He noted too that spontaneous generation seemed to take place when earth was warmed. Even though he could not grasp the importance of this as we can today, he still recorded it as part of his investigation. He concluded by leaving the issue open: “More accurate investigation must be made of the subject and the matter in which spontaneous generation takes place be thoroughly inquired into . . . This is why an experienced person is needed to gather it [the evidence], who has the ability to observe the proper season and recognise the seed itself.” For Theophrastus it remained a possibility that every form of apparently spontaneous generation would one day be explained, although he insisted that the concept remain in place until it was actually disproved by empirical observation. He was also insistent on the importance of professional expertise, another important development in the history of science. 21
    Crucially, Theophrastus was not prepared to accept the views of even such a great scientist as Aristotle (who also happened to be an associate of his) uncritically. He actively sought out explanations (the tiny seeds) that might undermine Aristotle’s suggestion. This was fundamental to the nature of Greek science. It was essentially competitive, with each scientist not only building on earlier observations but seeking to outdo his predecessors. Geoffrey Lloyd sums up its distinctive nature:
    The extant remains of Egyptian and Babylonian medicine, mathematics and astronomy can be combed in vain for a single example of a text where an individual author explicitly distances himself from, and criticises, the received tradition in order to claim originality for himself, whereas our Greek sources repeatedly do that. 22
    Lloyd gives a wide range of examples from medical treatises where an author explains what he believes, the observations on which the belief is based and why it differs from what has been believed before. Anyone, even an Aristotle, could be challenged by anyone who comes after. There can be certainty, in