Dear all,
Thank you for the contributions and reactions to my initial post. Since I am not an expert on information theory, I must resist the urge to comment on more technical aspects of the subject that have been raised. Let me concentrate instead on what may be an underlying issue. I sense some scepticism about my contentions that ancient science could never have developed into what we call modern science. There also seems to be an assumption that freedom of thought must be good for science. I'm not sure this is true. This has much to do with the way theories (that is, information about nature) are constructed and judged. In both these areas, the Greek philosophy of science was wanting. In other words, it could neither generate true theories nor determine which theories were true. Let me take Aristotle as an example. One example of Aristotle's physics going badly wrong is his theory of motion. It is explained in one of his most difficult texts, The Physics. To be fair, Aristotle is often not as dogmatic about his theory as his successors took him to be. But his careful reasoning makes arguing with his conclusions seem very difficult. He started with the observation that when an object falls, it keeps moving until something stops it. If you drop a stone, it falls until the ground intervenes to halt it. On the other hand, in all cases other than falling, objects appear to need something to move them. For instance, a chair will remain stationary unless someone pushes it. When they stop pushing, the chair stops moving. >From these observations, Aristotle formulated a general rule. There are, he said, two kinds of motion. There's natural motion like a rock falling under gravity and there is forced motion such as when someone pushes a chair. Each kind of motion is subject to different rules. For natural motion, objects have a property of heaviness or lightness. The heavier an object is, the faster it falls under gravity. So a brick, which is heavier than a feather, falls faster. For forced motion, Aristotle formulated a theory that linked the force pushing an object with its weight and friction. He correctly realised that the medium through which an object is moving is closely related to how it moves. So an object moving through air is subject to less resistance than an object moving through water. The speed at which an object moves, he said, must be proportional to the density of the medium through which it is moving. Water is denser than air so objects moving through it, subject to the same force, go more slowly. He then gives us an egregious example of where his reasoning goes badly off the rails. It is logical that when a medium has no density, such as a vacuum, objects would move through it with infinite speed. But that is impossible. So a vacuum must be impossible. The result of Aristotle's perfectly rational method was a theory of motion that required heavy objects to fall faster than light ones (which they don't); for something to stop moving if it stops being moved (which it doesn't) and for a vacuum to be impossible (it isn't). Aristotle's theology was at least part of the problem. Although he believed that a god of sorts existed, it was not the creator of the world. The world was eternal and so it could not be the product of an 'intelligence' or, indeed, of anything else. It seemed to follow from this that the rules the world followed could only be those of the strictest logic. Logic is always true everywhere and so it appears to be the only system from which the eternal workings of the world could be derived. This provided grounds for Aristotle's rationalism when explaining how the world worked. But Aristotle was only one philosopher who subscribed to a particular theology. There were loads of others. This religious and philosophical free-for-all produced an astonishing variety of scientific and metaphysical thought. And by carefully picking through them, we can find plenty that seems to be reflected in modern science. The problem is that this variety hides a lack of what we could call progress. With no one singing from the same hymn sheet, the discord of theories hid any advances that there were. No one had any idea how to determine who was right and who was wrong. The concept of experiment and falsification did not exist. Besides, everyone agreed that reason was the way to settle these disputes, not observation. Of course, freedom of religion and the freedom to dissent from received ideas are good things in themselves. But without an agreed way to decide the 'right' answer, progress in science is impossible. The Greeks thought that reasonable people should always be able to disagree. But scientific progress is marked by the point where reasonable people are compelled by the evidence towards consensus. Thus in Greek science, the signal to noise ratio was far too high for there to be significant progress. What information there was could not be picked out of the background and was often lost before it could be built on. The only exception was in mathematics where pure rationalism can serve to both generate and recognize true theorems. For these reasons, some sort of orthodoxy, rather than "anything goes" may be good for science. Best wishes James The Genesis of Science: How the Christian Middle Ages Launched the Scientific Revolution <http://www.amazon.com/Genesis-Science-Christian-Scientific-Revolution/dp/15 96981555/bedeslibrary> by James Hannam is available for pre-order now. "Well-researched and hugely enjoyable." New Scientist "A spirited jaunt through centuries of scientific development. captures the wonder of the medieval world: its inspirational curiosity and its engaging strangeness." Sunday Times "This book contains much valuable material summarised with commendable no-nonsense clarity. James Hannam has done a fine job of knocking down an old caricature." Sunday Telegraph
_______________________________________________ fis mailing list fis@listas.unizar.es https://webmail.unizar.es/cgi-bin/mailman/listinfo/fis
