René Descartes in his book, Meditations (1642), discussed the idea that he might be deceived by a malign genius, "some evil demon, who has used all his artifice to deceive me". A more contemporary example would be a virtual reality machine into which we could be plugged, feeding us all sensory information. Could we know anything? Could we ever know that we were not being fed a 'virtual' reality?

If we assume that we have been fed all sensory input via a machine, then we must distrust everything we have ever experienced. We cannot know if this experience is a result of the machine or our own perceptions. Thus all empirical knowledge must be disregarded, Descartes argued, as it cannot be proved to be true.

So what could we know? Mathematical or rational truths could surely remain true. Descartes considered the idea that his demon could simply cause him to believe that 2+3=5, and that this may not be the case. However, rational truths are by definition always true, independent of human perception or experience. Thus, rational truths remain true, although it can be argued by Descartes reasoning that what we consider to be rational truths are a product of our deception.

So we even doubt the rational truths we think we know. Surely all is lost? Descartes then constructed an argument that formed the basis of modern philosophy, something that remained true even if all else was false. He postulated that as he could doubt, and that doubt was a type of thought that he must be a 'thinking being'; by using his mind he affirmed the existence of his mind. He concluded cogito ergo sum: I think, therefore I am. This statement is self-affirming, since any attempt to doubt it simply proves it to be true.

Building from this firm foundation we can now attempt to answer the question by asking, what do we know about the nature of reality? What do we mean by reality? The concept reality means to each of us what we perceive, what we experience. Thus what we perceive must be reality as long as the concept remains the same. There can be no 'virtual reality' as whatever we experience is reality to us. Any virtual reality introduced to us simply becomes the new reality.

Following this idea we can also say that there is no one 'true' reality with which to compare any given perception of reality; as reality is simply what is experienced by the individual, and this perception may be different for each individual.

Therefore, although we cannot know if we are being deceived by a Cartesian demon, the question does not need to be answered as whatever we perceive is reality, and thus 'virtual reality' is an impossibility.

Tutor: Oliver McAdoo MA

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