Does the External World Really Exist?
On what grounds are we justified in believing in an external world?
Is the external physical world as we perceive it or is the true nature of reality very different? Indeed, are our perceptions caused by an external world at all – could it be that the world is merely a convincing simulation created by a supremely intelligent and manipulative demon? Perhaps nothing exists except our mind and the demon. In this essay we shall question our common sense belief in an external world. Following Descartes ‘method of doubt’ we shall systematically destroy the foundations for this belief to arrive on the bleak, featureless plain of hyperbolical doubt. We shall then attempt to claw our way back to an objective reality by examining objections to the sceptical conclusion. The journey will raise questions about the existence of other minds and the very language we use to express our scepticism.
What do we mean by ‘the external world’?
By ‘external world’ we refer to the totality of objects and phenomena which exist independently of our mind and which are revealed to us through perception (sense data). This is the domain for which science attempts to provide a causal explanation for how the objects of the world act on each other and on our senses. We have no direct contact with the external world but derive knowledge of it through rationalisation of the patterns in the sense data (qualia) we experience. We hypothesise that our senses reveal a world of objects which have extension in space and time and which have causal relationships with each other and, through our senses, with ourselves. Our rational minds correlate and classify sense data into abstract classes and concepts, identifying instances of known classes or combining classes into composite concepts which may or may not exist in some external world (unicorns for example). Our mental model is intentional; containing tokens which are ‘about’ objects in the real world, linked by...