Today, Aristotle (384–322 BC) has a reputation as a philosopher. However, he was also a natural historian. He had much to say about living things and the universe in general. Formerly, his views formed the basis of much thinking about the universe. His philosophical ideas are still pertinent, but his scientific ideas are less so. They are of more interest to historians of science than to scientists. How Aristotle lost this seemingly unimpeachable reputation is particularly interesting (and perhaps less well-known to scientists). How he fell out of favour influenced how modern science operates.
For over a thousand years, the writings of the ancients - in particular, Aristotle - were the ultimate authorities in scientific matters. In the sphere of anatomy and physiology, for example, the works of Galen (129-c216) were adhered to strictly. Human dissections at medical schools were demonstrations of what Galen had stated centuries before. They were not a means of discovery. A professor - seated above proceedings - would read from Galen while a junior colleague under his direction would perform the dissection.*
In the thirteenth century, the Roman Catholic church in Paris, keen to counter - what it considered - heretical teachings, published a list of 219 propositions whose discussion was forbidden. Neither could these be read about - even in private! Prohibition was not limited to theological ideas. An ecclesiastical condemnation published in 1210 prohibited Aristotle’s books on natural philosophy (i.e. physics) from being read. Even reading commentaries was forbidden. (His philosophical works were not directly affected.) The penalty was excommunication. (Excommunication implied eternal damnation to hell fire.)
Initially, that condemnation only applied in Paris. Other cities in France were unaffected. Aimed at attracting students, some universities even advertised that they allowed the reading of things forbidden in Paris!
An unforeseen consequence of the condemnation was that without the authority of Aristotle upon which to rely, the only option was to find out for oneself. Thus, an intellectual shift away from the reliance on ancient authority began.
Simple reflection must recognise how relying on authority must result in intellectual stagnation. Often, a plurality of possible positions exists. No authority can advocate a plurality of positions. Authorities can hold only a single position. By definition, that position must be the right one. There is no need to develop ideas if they are right. Hence stasis. Only a revolution in thinking can change this. An authoritative position presupposes perfect knowledge of all relevant facts. Nobody can genuinely claim this. Thus, there can be no authoritative positions in science.
Later, Hegel (1770-1831) proposed that knowledge could progress via dialectic between a thesis and an antithesis. There can be no completely authoritative positions. Every position is provisional, dependent on the current state of our knowledge.
Note
* There are two approaches that one can take when dissecting a human body.
(a) One takes a dissecting guide and follows its instructions closely. When I was teaching medical students, this was the approach prescribed. Classes of this type have something in common with those of old. Professors no longer sit directing proceedings, but dissection is still strictly guided.
(b) One opens the body to see what is inside. It is helpful to know what to expect in advance. However, this is not essential. One then identifies the findings. When I was a (non-medical) undergraduate on a course that permitted human dissection, we adopted this approach. We knew what we were looking for, but we went about it in our own way.
