Monday, May 16, 2016

The end of the universe

In these blogs I talked already several times about thought experiments. Thought experiments are used in all kinds of philosophy but especially when discussing questions concerning man’s personal identity and analyzing ethical problems. The reason is that it is often impossible to do real experiments in these fields, for practical or for moral reasons. For example in the debate on personal identity it often happens that brains are switched between two persons. Should we take the risk that a man wouldn’t survive such an operation just for the sake of testing or developing a philosophical theory? So we use our imagination for answering our questions.
The first philosopher who used a brain switching thought experiment was John Locke in 1694 in his An Essay concerning Human Understanding. (Actually, Locke didn’t switch the brains but the bodies of a prince and a cobbler in his case). Before Locke Descartes used already thought experiments, for example when he developed the theory that led to his statement “Cogito ergo sum” – I think so I am. However, thought experiments are much older and also Greek philosophers employed them, although they didn’t call them by that name. Some of their cases are still used by modern philosophers, like “The Ship of Theseus”. One version of it is that gradually the planks of Theseus’ ship are replaced by new planks but that the old planks are again used for constructing a new ship. Which ship is the real ship of Theseus?
Although “Theseus’ Ship” is the best known thought experiment from classical philosophy, it is not the oldest one. That’s one ascribed to Archytas of Tarentum (428-347 BC), so Katerina Ierodiakonou in a Dutch philosophy magazine. His thought experiment is the first one that has been recorded. Archytas worked in the tradition of Pythagoras’ School and he is an interesting person. He is said to be the founder of mathematical mechanics and to have developed a kind of airplane that has even flown over a short distance. But that’s not what I want to talk about here. I think that for historical reasons, but also for philosophical reasons, this oldest thought experiment is interesting, also because it’s one that can be used in present-day philosophical debates. When discussing the problem whether the universe is finite or infinite, Archytas says: Suppose that you arrive at the end of the universe and extend a staff. Then you touch either a body or it is possible to extend the staff in empty space. In both cases you will not have reached yet the end of the universe and you can go on and repeat the same action when you have arrived at what you think now as the end of the universe, which will lead to the same result. The upshot is that the universe is infinite. What Archytas did not and could not consider is that the universe might be curved, so that nevertheless it could be finite. Is it important? As Karl Popper told us, every answer is significant for it gives us a starting point to discuss about and to improve it. But despite that, Archytas’s thought experiment is not only a contribution to the cosmological theory, but it has also a psychological meaning, for instance – “for instance”, for I guess that it can be given very different interpretations –: Even if you think that you have come at the end of your mental possibilities (for example in a conflict), stretch your mind and you’ll see that there still is some space to move and to solve your problem and to solve your inflexibility. Thinking is infinite, as are our ideas.

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