To: Katherine A.
From: Geoffrey Klempner
Subject: What holds the world up?
Date: 30 January 2007 09:47

Dear Katherine,

Thank you for your email of 21 January, with your first essay for the Ancient Philosophy program, in response to the question, 'Why does the Earth (appear to) stand still? Discuss this with reference to the theories of Thales, Anaximander and Anaximenes.'

This is a very readable essay. You are right to emphasise the importance of the tendency to believe that we are the centre of the cosmos.

I can beat your mother-in-law story: when I first started teaching philosophy, I had a student who believed that the Earth was flat. She was a woman in her 70's and a Quaker. When she was 8, someone had showed her a globe and she thought, 'No way.' And that was that. It provided a very entertaining distraction as each of the other students in turn tried, and failed, to 'prove' that the Earth is round.

Of course, it is just conceivable that she was kidding. But she convinced us that she wasn't.

The question is why does the Earth (appear to) to stand still. I put 'appear to' in brackets to make it clear that we are evaluating explanations of a certain phenomenon which we can all agree about. Whether the Earth moves or not, in reality, is something that one cannot tell just from appearances. Thales, Anaximander and Anaximenes all sought to explain how it is that this appearance is veridical, and not an illusion.

But DOES the Earth appear to stand still? This might seem obvious. You give the nice illustration of the donkey. Obviously, if the Earth was a donkey you would be very much aware of its movement. But that idea is absurd: if the Earth is a donkey then how is it that everyone manages to fit on it?

In that case, how would something very, very big - as big as the Earth must be in order for everyone to fit on it - appear to move? What possible experience could be an 'experience of a moving Earth'? In earthquakes, the Earth certainly 'moves', but that is not the same as the experience of moving along, as on a donkey traversing a rocky path. If there is nothing that could count as the experience or appearance of an Earth moving along, then it is arguably incorrect to say that the Earth 'appears' to stand still.

According to Thales, the Earth floats on water. (You refer to 'Thales' water spout' but the idea of a spout is more appropriate for Anaximenes, see below.) How good an explanation is this?

In order to evaluate the explanation, we have to start by assuming something which we know in fact to be false: that it is a universal law that 'things fall down' and that there is one, and only one direction which is 'down'.

Things dropped fall to the Earth because things fall down. But the Earth is not itself falling down because the water supports it. However, the question then arises, why the supporting water does not 'fall down'? In the unit I suggest that Thales' idea was, 'If you go down, it's water all the way.' In other words, there is nothing for the water to fall into, no empty space underneath. There is no textual evidence, however, that Thales considered the supporting ocean to be infinite in extent, which is what it would have to be to 'go down' forever.

The main point of Anaximander's ingenious theory, by contrast, is to question the assumption that 'things always fall down'. What if, falling down is only something that happens where there is an asymmetry of some kind? What if, an Earth positioned precisely in the centre of the cosmos stayed where it was because there is 'no more reason' for it to go one way or another. At the centre of the cosmos there is no difference between 'up' and 'down', everything is the same whichever way you look. That seems to have been his idea.

You say, 'Anaximander was not drawn specifically on what kept the Earth supported in mid air.' However, the point of Anaximander's theory is that the Earth does not need any support, because it has 'no reason' to go one way rather than another. If you like, it is 'supported' by the logic of the 'no more reason' argument.

Anaximenes had an ingenious theory of his own. The earth is supported on air. Logically, he would have to say this if he is following Thales lead and identifying the thing that everything is made of (water, or air) with the thing that supports the Earth. There is only one problem with this: air is not very effective at holding things up. So he hit on the brainwave of a continual powerful updraft of air that supports the Earth in the same way as the steam coming out from a boiling pot is able to lift a heavy iron lid. Hence the deliberately provocative claim that the Earth floats on air 'like a leaf'. It took a tremendous leap of imagination to picture the Earth, from a sufficiently wide perspective, as a mere leaf borne aloft in the wind.

All the best,

Geoffrey