Avicenna’s Argument

Avicenna was apparently one of the most important polymaths in the so called “Golden Age of Islam”. He lived in Persia from 980 to 1037 and was renowned in many fields of knowledge, even to the extent that one of his textbooks on medicine was still used as the core text in Montpellier and Louvain in the mid 17th century.

One of the great ideas of Avicenna was his argument for the existence of God which, to me at least, smacks very much of mathematical proof (and is therefore understandably quite appealing to one such as myself…). So, what’s it all about?

Avicenna uses heavily the concept of contingency. A state of affairs is contingent if it could have been otherwise. So for instance, my mother at some point had a child: me. It was by no means a logical necessity that she do this – I might not have been born. Therefore my existence is contingent upon the fact my parents decided to have a child. Similarly their existence is contingent upon their parents having had children, and so on… Avicenna’s argument tries to construct a necessary object and then calls that God.

Ok. So the world contains a great many contingent things (like me for instance). The existence of each one of these things must therefore have been caused by something else which is itself contingent and so on and so forth… Such and such a table was made by a carpenter whose existence was caused by his father and mother etc. So we get a big long causal chain of events which are all contingent. The usual (cosmological) argument for the existence of God says at this point that this chain must stop somewhere so we get an ‘uncaused causer’, which is taken to be God.

Avicenna comes up with a slightly subtler approach. He basically defines ‘the world’ as the set of all contingent things and all the causes between them. He then states a principle of composition which, applied here, says that the set of all contingent things is also contingent. Since the world is therefore contingent, it must be caused by some object X outside the world. Suppose X is contingent. Then it must be part of the world, which is impossible. Therefore X was in fact not contingent, i.e. necessary. He defines this X to be God.

Of course, as with any argument for the existence of God, there are quite a few problems with this:

  1. What justification do we have that anything is contingent in the first place?
  2. How do we know that this X is the God of (in Avicenna’s case) Islam as opposed to just some abstract object? That is, how do we arrive at any of the traditional attributes of God such as omnipotence etc.?
  3. What’s all this principle of composition about? Admittedly, if I have a car, all of whose components are blue, then my car will be blue. But if I have a car, all of whose components are well made, then it’s certainly not true that the car itself must be well made.

Despite all of these, I think it’s a pretty cool argument and echos Russell’s paradox which came much later.
Here’s a nice Rube Goldberg example of a set of contingent events:

Flame from lamp (A) catches on curtain (B) and fire department sends stream of water (C) through window. Dwarf (D) thinks it is raining and reaches for umbrella (E), pulling string (F) and lifting end of platform (G). Iron ball (H) falls and pulls string (I), causing hammer (J) to hit plate of glass (K). Crash of glass wakes up pup (L) and mother dog (M) rocks him to sleep in cradle (N), causing attached wooden hand (O) to move up and down along your back.

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