Descartes, as we have seen (extract 3, above) regarded matter as inert, passive extension; and both he and Locke considered that our ideas of sensible properties (such as colours, tastes, smells) did not really inhere in, or belong to the physical world, but rather were effects produced in the mind alone. Reflection on these issues led the Irish philosopher George Berkeley to the radical conclusion that nothing at all could be said to exist outside the mind. In the following extract from the Principles of Human Knowledge (1710), he attacks the Lockean distinction between primary and secondary qualities (see above, extract 4), and insists that all the arguments applying to sensible properties (like colour) apply equally to the supposed primary qualities (such as extension and shape): ‘where the other sensible qualities are, there must these be also, to wit in the mind, and nowhere else’.
Berkeley’s immaterialism has often been regarded as an affront to common sense (Dr Johnson famously ‘refuted’ it by simply kicking a stone). But Berkeley (as is clear from our extract) refers quite happily to ‘houses, mountains and rivers’, and to ‘all those bodies which compose the mighty frame of the world’. He does not deny the reality of such things, but asserts that their existence consists in their being perceived (or, as Berkeley puts it in Latin, their esse is percipi). So does the table in my study continue to exist when there is no one in the room? Berkeley suggests at one point that to say it does means that if I were in my study I would perceive it (a view sometimes called ‘phenomenalism’ – the analysing of physical objects as ‘permanent possibilities of sensation’). But Berkeley’s more characteristic line is to say that tables, chairs, mountains, rivers and all natural phenomena do indeed have a being independent of the human perceiver. They subsist as ideas ‘in the mind of some Eternal Spirit’; the uniformity and regularity of things, which we know is not dependent on us, ‘testifies the wisdom and benevolence’ of that governing spirit whose will generates those regular successions of ideas which we call the ‘laws of nature’. Berkeley’s metaphysical immaterialism is thus linked to his theology: in place of what he regarded as the godless materialism of those who conceived of the physical world as an alien reality, existing ‘out there’ independent of the mind, Berkeley offers a picture of reality as something essentially mind-dependent, and grounded in the divine consciousness. His labours will have been useless, he went on to observe in the closing paragraph of the Principles, unless he can ‘inspire his readers with a pious sense of the Presence of God’.
It is evident to anyone who takes a survey of the objects of human knowledge that they are either ideas actually imprinted on the senses; or else such as are perceived by attending to the passions and operations of the mind; or lastly ideas formed by help of memory and imagination, either compounding, dividing, or barely representing those originally perceived in the aforesaid ways. By sight I have the ideas of light and colours with their several degrees and variations. By touch I perceive, for example, hard and soft, heat and cold, motion and resistance; and of all these more and less either as to quantity or degree. Smelling furnishes me with odours, the palate with tastes, and hearing conveys sounds to the mind in all their variety of tone and composition. And as several of these are observed to accompany each other, they come to be marked by one name, and so to be reputed as one thing. Thus, for example, a certain colour, taste, smell, figure and consistency having been observed to go together, are accounted one distinct thing, signified by the name apple. Other collections of ideas constitute a stone, a tree, a book, and the like sensible things; which, as they are pleasing or disagreeable, excite the passions of love, hatred, joy, grief, and so forth.
But besides all that endless variety of ideas or objects of knowledge, there is likewise something which knows or perceives them; and exercises divers1 operations, as willing, imagining, remembering, about them. This perceiving, active being is what I call mind, spirit, soul or myself. By which words I do not denote any one of my ideas, but a thing entirely distinct from them, wherein they exist, or, which is the same thing, whereby they are perceived; for the existence of an idea consists in being perceived.
That neither our thoughts, nor passions, nor ideas formed by the imagination, exist without the mind,2 is what everybody will allow. And it seems no less evident that the various sensations or ideas imprinted on the sense, however blended or combined together (that is, whatever objects they compose) cannot exist otherwise than in a mind perceiving them. I think an intuitive knowledge may be obtained of this by anyone that shall attend to what is meant by the term exist when applied to sensible things. The table I write on I say exists; that is, I see and feel it; and if I were out of my study I should say it existed, meaning thereby that if I was in my study I might perceive it, or that some other spirit actually does perceive it. There was an odour, that is, it was smelled; there was a sound, that is, it was heard; a colour or figure, and it was perceived by sight or touch. This is all that I can understand by these and the like expressions. For as to what is said of the absolute existence of unthinking things without any relation to their being perceived, that seems perfectly unintelligible. Their esse is percipi, nor is it possible they should have any existence, out of the minds or thinking things which perceive them.
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?
If we thoroughly examine this tenet, it will, perhaps, be found at bottom to depend on the doctrine of abstract ideas. For can there be a nicer strain of abstraction than to distinguish the existence of sensible objects from their being perceived, so as to conceive them existing unperceived? Light and colours, heat and cold, extension and figures, in a word the things we see and feel – what are they but so many sensations, notions, ideas or impressions on the sense? and is it possible to separate, even in thought, any of these from perception? For my part I might easily divide a thing from itself. I may indeed divide in my thoughts or conceive apart from each other those things which, perhaps, I never perceived by sense so divided. Thus, I imagine the trunk of a human body without the limbs, or conceive the smell of a rose without thinking on the rose itself. So far I will not deny I can abstract, if that may properly be called abstraction, which extends only to the conceiving separately such objects, as it is possible may really exist or be actually perceived asunder. But my conceiving or imagining power does not extend beyond the possibility of real existence or perception. Hence as it is impossible for me to see or feel anything without an actual sensation of that thing, so is it impossible for me to conceive in my thoughts any sensible thing or object distinct from the sensation or perception of it.
Some truths there are so near and obvious to the mind that a man need only open his eyes to see them. Such I take this important one to be, to wit, that all the choir of heaven and furniture of the earth, in a word all those bodies which compose the mighty frame of the world, have not any subsistence without a mind; that their being is to be perceived or known; that consequently so long as they are not actually perceived by me, or do not exist in my mind or that of any other created spirit, they must either have no existence at all, or else subsist in the mind of some Eternal Spirit: it being perfectly unintelligible, and involving all the absurdity of abstraction, to attribute to any single part of them an existence independent of a spirit. To be convinced of which, the reader need only reflect and try to separate in his own thoughts the being of a sensible thing from its being perceived.
From what has been said it follows there is not any other substance than spirit, or that which perceives. But for the fuller proof of this point, let it be considered, the sensible qualities are colour, figure, motion, smell, taste, and such like, that is, the ideas perceived
