The Closing of the Western Mind by Charles Freeman

Aristotle (Metaphysics, quoted in “The Closing of the Western Mind”, by Charles Freeman)

The investigation of truth is in one way hard, in another easy. An indication of this is found in the fact that no one is able to attain the truth adequately, while, on the other hand, no one fails entirely, but everyone says something true about the nature of things, and while individually the contribute little or nothing to the truth, by the union of all a considerable amount is amassed.

“The Closing of the Western Mind”, Charles Freeman, pp 21-22.

While Aristotle believed that an underlying unity would be found to all knowledge, he accepted that in the present state of knowledge much must remain provisional and unsure. Take, for example, a difficult question in the natural world, how to differentiate between “plants” and “animals.” A dogmatic scientist might have drawn up some arbitrary rules and simply classified each organism as one or the other. Aristotle realized that this was to avoid the real issue. He took some examples from the marine world, the sponge, the jellyfish, sea anemones, razor shells. He noted that when a sponge was pulled from a rock to which it was attached, it reacted by clinging to the rock. So perhaps it was some kind of animal. Yet it could not live detached from the 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.

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 the 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 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.