Sunday, 12 September 2010

Metaphysics 101

Kant's left handed universe

Is space absolute or relative? Newton thought that it was but Leibniz argued that if you created another universe but with everything translated then it would be the same, as only the distances between particles (internal coordinates) matter.

Kant created a thought experiment to show Newton was right and Leibniz wrong by imagining a universe that contains only a left hand. Then if you create another universe this time with an identical left hand then while all the internal distances are the same these two universes are clearly not the same as they are mirror images of each other.

Now we have general relativity that shows that space is like a plastic sheet that folds and so the space we see are all those points that share the same time. The bending is caused by gravity and acceleration, which are equivalent.

The reason why relative and absolute are important comes when we consider,

Laplace's Demon

If the universe is composed of atoms (using atoms in the broadest sense to mean particles), and these are governed by the laws of physics then if there is a super intelligent demon that knows the positions and velocities of all the particles at a particular time. Then they can calculate the positions and veolicities for any other time and the future would be completely determined. There would be no possibility of having free will other than as an illusion. We would be destined to have the life we have.

Some argue that quantum mechanics removes this rigid determinism but this was the root of Einstein's famous saying that "God does not play dice". He means that the probabilities of quantum mechanics cannot apply to determinism and in particular the theory must retain causality. Events cause future events to happen. If causality is broken then there are no laws. Chaos is another example of what seems like random behaviour but it still maintains rigid determinism, it just requires an even higher standard of knowledge for the Demon.

Ryle's Ghost in the Machine

Descartes introduced the idea of dualism, i.e. mind stuff is different to physical stuff. This causes problems with understanding how the two interract. Gilbert Ryle thought this was the wrong view. For him they are an undivided whole and the body and its activities comprises the mind - a way of describing the machine's activities. In more modern terms we can imagine that mind "emerges" from the components of the body.

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