Bishop Berkeley: is there an external world?

George Berkeley (1685-1753)

George Berkeley, born in 1685 at Dysart Castle in County Kilkenny, and Bishop of Cloyne from 1734 to 1753, wrote a philosophical analysis of materialism which has been the subject of controversy since its publication.

Berkeley attacked the belief in material objects that underlay the prevailing scientific model of the world. He argued that there was no basis for a belief in physical objects or an external world, and that we should think of all objects as being mental.

It is indeed an opinion strangely prevailing amongst men, that houses, mountains, rivers, and in a word all sensible objects, have an existence, natural or real, distinct from their being perceived by the understanding. But with how great an assurance and acquiescence soever this principle may be entertained in the world; yet whoever shall find in his heart to call it in question may, if I mistake not, perceive it to involve a manifest contradiction. For what are the forementioned objects but the things we perceive by sense? And what do we perceive besides our own ideas or sensations; and is it not plainly repugnant that any one of these or any combination of them should exist unperceived? *

Modern philosophers have tended to marginalise Berkeley because his views appear to be radically at odds with the conventional scientific worldview. Bertrand Russell, for example, took Berkeley’s arguments seriously but felt justified in dismissing them.

In one sense it must be admitted that we can never prove the existence of things other than ourselves and our experiences. No logical absurdity results from the hypothesis that the world consists of myself and my thoughts and feelings and sensations, and that everything else is mere fancy. [...] There is no logical impossibility in the supposition that the whole of life is a dream, in which we ourselves create all the objects that come before us. But although this is not logically impossible, there is no reason whatever to suppose that it is true; and it is, in fact, a less simple hypothesis, viewed as a means of accounting for the facts of our own life, than the common-sense hypothesis that there really are objects independent of us, whose action on us causes our sensations.

The way in which simplicity comes in from supposing that there really are physical objects is easily seen. If the cat appears at one moment in one part of the room, and at another in another part, it is natural to suppose that it has moved from the one to the other, passing over a series of intermediate positions. But if it is merely a set of sense-data, it cannot have ever been in any place where I did not see it; thus we shall have to suppose that it did not exist at all while I was not looking, but suddenly sprang into being in a new place. **

In these extracts from his book The Problems of Philosophy, Russell mentions some of the apparent problems of Berkeley’s thesis. It seems natural to one to suppose that, during the time between seeing the cat the first time and seeing it the second time, something exists which one can label as ‘the cat’, even if no one is having sensory experiences involving this inferred cat. However, the fact that positing such an independent entity may seem natural, or convenient, does not constitute philosophical proof.

* George Berkeley, A Treatise Concerning the Principles of Human Knowledge, in A.J. Ayer & R. Winch (Eds.), British Empirical Philosophers, Routledge and Kegan Paul 1952, p.179.
** Bertrand Russell, The Problems of Philosophy, Williams & Norgate 1912, pp.30-36.