Have you ever wondered whether you’re stuck in a computer simulation; just a brain in a vat, a helpless victim of a twisted scientific experiment? Is the world around you just a figment of your imagination? You may quickly dismiss such thoughts—but can you prove it isn’t true?

This was the disturbing problem proposed by the philosopher Hilary Putnam in 1981, but it closely resembles René Descartes’ idea of the Evil Genius, presented in his 1641 work Meditations on First Philosophy. Descartes wanted to investigate which of our assumptions about ourselves and our world we can actually show to be true, and his starting point for this was to doubt absolutely everything until we can be sure of it— “if you would be a real seeker after truth”, he says, “it is necessary that at least once in your life you doubt, as far as possible, all things”. Since he knows that his own senses have not always been accurate in the past, he concludes that he cannot be completely sure even that the pipe in his hand or the slippers on his feet are really there. Taking this idea to another level, Descartes imagined that there might be an omnipotent evil genius, a “malicious demon”, tricking us into believing everything we think we see around us and everything we think we know about our own lives, when in fact reality could be totally different.

This scepticism and doubt about our own senses and perceptions can be seen in popular culture, most notably in the 1999 film The Matrix and the 2010 film Inception. Such fictional accounts reflect our own niggling fears that perhaps we cannot trust anything at all, which are arguably heightened in our modern world of virtual reality technology and artificial intelligence.  Can we at least be sure that we ourselves exist? Descartes’ answer is yes, because if we are doubting everything around us there must be a thinking entity, an “I”, doing the doubting—I think, therefore I am.

Applicants wishing to study Philosophy should familiarise themselves with Descartes’ famous sceptical argument, and should think about their own response to the issue of reality and the senses. Is radical doubt the correct starting point? How, if at all, can we prove the reality of our perceptions? If we were all living in a computer simulation, would there be any way for us to know it? Finally, is “I think, therefore I am” a well-reasoned argument?

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