George Berkeley 1685-1753
George Berkeley was born at Kilcrene near Kilkenny on the 12th March 1685. In the year 1700 he entered Trinity College Dublin, and graduated four years later with a B.A. degree. He became a Fellow of the College in 1707, and was ordained as a priest of the Protestant Church in 1710. In 1724 he was appointed Dean of Derry, and became Bishop of Cloyne ten years later. He served faithfully and competently in that position for eighteen years, refusing an offer of the more prestigious Bishopric of Clogher, and retired in 1752. He settled at Oxford with his wife and family, and died suddenly on 14th January 1753.
This brief chronicle of Berkeley's ostensibly uneventful life tells us nothing about the character of the man himself, nor does it indicate why the individual concerned was to become firmly established, with John Scotus Erugena, as one of the two truly great and original philosophers which this country has ever produced. In this regard, therefore, it may be as well to begin by observing that Berkeley's literary and artistic talents were almost as great as his philosophical ones: his prose style is fluent, lucid, precise, cogent and witty, end he is one of the very few great masters of the dialogue-form in the English language. His interests were neither exclusively nor even predominantly philosophical: as a Christian Bishop he was of course primarily concerned with the religious dimension of human life, and this concern evidenced itself in the plan which he put forward for the establishment of a College in Bermuda in 1723. The purpose of the College was to have been the provision of a religious and general education for the English settlers and native Indians of the New World, but despite Berkeley's own very practical and strenuous efforts (he spent four years in Newport, Rhode Island, patiently waiting for a financial grant from the British Parliament for his proposed College to arrive), the plan was never implemented. His concern with religious and theological issues in general, especially in the bearing which they have upon the lives, beliefs and moral behaviour of mankind, was the single most influential feature in the growth of his intellectual life, and, as I hope to show, was to play an extremely significant role in the evolution of his philosophical thought. Berkeley's interests did extend, however, beyond the purely religious sphere: he travelled widely, to France and Italy as well as to the New World; was on intimate terms with such prominent literary figures as Pope, Swift and Steele, as well as with leading members of the Court and Parliament, and he had a deep and abiding interest in contemporary developments in the natural sciences. He also had a fundamental sense of commitment to the ideals of justice and social equity, and he worked strenuously to awaken public awareness to the high levels of poverty, ignorance and disease which were rampant in Ireland at the time, to the point where he made conciliatory overtures to the Catholic clergy with a view to enlisting their support in improving the economic welfare of the country. Indeed, while his famous (albeit unduly optimistic) dissertations on the medicinal properties of tar-water, which Berkeley believed to be a panacea for most physical ailments, may strike the modern reader as being unduly naive, they symbolise his genuine concern for his fellow-man, and his over-riding desire to ameliorate unnecessary suffering. He was, in short, by natural inclination an idealist, in the literal and most comprehensive sense of that term, and his determination to see his ideals realised transformed him into a man possessed by an urgent reforming zeal which was as much conceptual as practical, and which found expression both in his writings and in his activities. His espousal of the apparently extreme and paradoxical thesis that matter does not exist may in the first instance, I think, be viewed as a philosophical manifestation of this reforming zeal, motivated as it was by Berkeley's conviction that the concept of matter is confused and incoherent, which from time immemorial has served as the linchpin for both epistemological scepticism and atheism. (Cf. Principles of Human Knowledge, 92).
Unlike his predecessor Locke, therefore, whose philosophical writings were for the most part disinterested and detached, in the sense that they played no direct part in his daily life or his duties as a statesman and physician, Berkeley's interest in philosophy was motivated principally by his concern with the defence of orthodox Christianity against the dangers of materialism, scepticism, and ultimately, atheism, which he was convinced were inherent in the philosophical and scientific theories dominant in his day. Consequently the central thrust of his two major works, The Principles of Human Knowledge and Three Dialogues between Hylas and Philonous, is unashamedly apologetic, and this is reflected strongly in the subtitles which he appended to them:
The Principles: 'Wherein the Chief Causes of error and Difficulty in the Sciences, with the Grounds of Scepticism, Atheism, and Irreligion are inquired into.'
Three Dialogues: 'The design of which is plainly to demonstrate the reality and perfection of human knowledge, and the incorporeal nature of the soul, and the immediate providence of a Deity: in opposition to Sceptics and Atheists. Also to open a method for rendering the Sciences more easy, useful and compendious.' (Berkeley - Philosophical Works, ed. M. R. Ayers).
Berkeley was justified to a large extent, in my view, in thinking that the philosophical systems of Descartes and Locke - the latter of whom bears the brunt of Berkeley's attack - lead ultimately to scepticism, particularly in view of their perceptual representationalism, and this was one of the many theories which he determined to controvert. But the principal object of his attack was materialism, a doctrine which was implicit in the mechanistic account of the natural order advanced by Newton, Boyle, and the other 'corpuscular' theorists, elements of which Locke had incorporated into his philosophical system. Locke had argued, in his Essay Concerning Human Understanding, that the mind, observing, through the mediation of its ideas, that clusters or complexes of qualities occur in regular sequences, tends naturally to explicate such sequences in terms of the intrinsic 'powers' and 'properties' which objects possess as part of their 'real essences', i.e. their molecular configuration or structure. By this means the mind is naturally led to the conception of a material substratum as something which 'underlies' and 'supports' the sensory qualities which we perceive and know: 'the supposed, but unknown support of those qualities we find existing, which we imagine cannot exist sine re substante' (Essay,11.xxiii.2). Locke accepted, in other words, a modified version of the Aristotelian doctrine that material substances are the ontological correlates of logical subjects - they are the things which possess qualities, such as extension, figure and motion. But Locke himself had acknowledged that if we attempt to abstract from our ideas of these qualities, we are left with only the vaguest notion of an indeterminate substratum. Yet Locke persisted in arguing that it is this substratum which unifies and integrates the qualities instantiated in it. Moreover, he also held that the 'real essences' of objects, which in principle are incapable of being comprehended by the human mind, determine the structure of all complexes of qualities, are 'situated' in the indeterminate substratum, and are capable of being understood by a being with adequate, superhuman faculties. Thus Locke held that we know only things as they systematically appear to us, conditioned by the perceptual process; things as they actually are in themselves lie forever beyond the reach of the human intellect. It is not difficult to see why Berkeley thought that this viewpoint contained the seeds of radical scepticism - he was perhaps the first philosopher in modern times to see with crystalline clarity that scepticism is unavoidable once the real is placed beyond the reach of all possible experience. And he saw that the doctrine of material substance had precisely this effect.
Contemporary science too was a source of concern for Berkeley. At this time, of course, Newton's theory of universal gravitation dominated physics, and Newton's law that bodies tend to move towards each other with an acceleration directly proportional to their mass and inversely proportional to the square of the distance between them was regarded by all and sundry as the very paradigm of scientific laws. However, in very many popular representations of Newton's theory not only was the natural order held to be explicable in purely mechanistic terms, but the law of gravitation itself was held to exemplify and underwrite the view that inanimate objects exert 'forces' upon each other at a distance (though Newton himself, it should be added, firmly repudiated this interpretation of his theory). Now Berkeley, incisive as ever, saw clearly that terms like 'force, 'attraction' and 'repulsion' could not be significantly used or understood in such contexts in anything other than a purely metaphorical way. He believed, correctly in my view, that it made no sense at all to treat inanimate objects or inert matter as causal agents in the sense in which human beings (or 'spirits', as Berkeley insisted on calling them) are causal agents. Yet many, if not indeed most, contemporary physicists treated inanimate objects as causal agents in precisely this way, and tended to assume that this is implied by mechanistic determinism. The concept of God functioning as immanent agent is expressly excluded on this view - the principle of parsimony renders the thesis that God is required to sustain and structure phenomena redundant. Moreover, since mechanistic determinism is compatible with the thesis that the agency of God is transcendent rather than immanent, it is not a viewpoint with which many modern theologians would necessarily find fault. But Berkeley did not see things quite that way. Like Plato in the classical world, he found the concept of inanimate material objects functioning as causal agents incomprehensible, anthropomorphic, and self-contradictory. For Berkeley, as for Plato, only a 'spirit' or soul could function as a causal agent in the literal sense, and he believed that the ultimate cause of all phenomena, in terms of which alone they can be explicated, is the cosmic spirit or mind of God. This naturally coloured his interpretation of, and reaction to, scientific mechanism: for Berkeley, as again for Plato, the only genuine form of explanation was teleological explanation in terms of final causes, and he viewed with disdain the contention of the 'corpuscularian' scientists that phenomena could be both described and explained in terms of the mechanical interaction of material objects and particles. It was against this attempt, as he saw it, to supplant God with inert matter that Berkeley reacted, arguing (not entirely without reason) that it constituted the first step towards atheism.
So much then for the general background to the evolution of Berkeley's ontology; I come now to his argument's for immaterialism. While Berkeley's philosophical system as a whole was designed to controvert the materialism of Locke and the natural scientists of his day, it nevertheless derives from epistemological principles which are remarkably similar to those of Locke. For not alone did Berkeley espouse Locke's empiricist thesis that all knowledge is derived from experience (cf. Principles, 1), he also followed Locke in accepting the Cartesian view of consciousness, viz. the thesis that the immediate object of perceptual experience is itself a mental event or an item of consciousness, which Berkeley, following the prevailing fashion of the day, termed an 'idea'. For Berkeley, as for Descartes and Locke, this seemed a truth so obvious as to require no vindication. (Thus in the Principles, 4 he asks 'what do we perceive besides our own ideas or sensations?', and assumes that it is self-evidently true that the only possible answer to this question is 'nothing').
As a result, the destructive effect which the acceptance of this precept had wrought upon the philosophical systems of Descartes and Locke was, unfortunately, to be repeated in Berkeley's, although it was to take a significantly different direction. For while Locke had tried to break through the so-called 'veil of ideas' which this precept erects between consciousness and the objective, extra-mental world by means of a causal or 'representationalist' theory of perception (i.e. the theory that the ideas or data of which we are aware in consciousness are 'caused by', and so represent, physical objects existing outside of the mind), Berkeley saw that this account of perception leads inevitably to scepticism about the nature and existence of the objective world, and so rejected it out of hand. Representationalism duplicates the world of perceptual experience with an unperceivable real world, and those such as Locke who subscribe to it have inevitably to admit that our knowledge of the real world is, at best, indirect and inferential in nature. In direct opposition to this Berkeley adopted the anti-sceptical position that the real world is directly or immediately encountered in perception, and that our knowledge of this world is direct and non-inferential. (Berkeley's succinct and brilliant critique of perceptual representationalism occurs in the Principles 8, and is further developed in 56-7). But if what we perceive immediately is the real, objective world, and we immediately perceive only our own ideas, then it follows analytically that our ideas are constitutive of reality, and are not, as Locke had argued, merely representative of reality.
This was the line of reasoning which led Berkeley to formulate his famous 'immaterial hypothesis', that an idea exists only insofar as it is perceived, and that a spirit or mind exists only insofar as it perceives or is conscious. Thus, at the end of the Third Dialogue, Philonous, who speaks for Berkeley, says:
My endeavours tend only to unite and place in a clearer light that truth, which was before shared between the vulgar and the philosophers: the former being of the opinion, that those things they immediately perceive are the real things; and the latter, the things immediately perceived, are ideas which exist only in the mind. Which two notions put together, do in effect constitute the substance of what I advance. (262).
Notwithstanding the commendable clarity with which Berkeley stated and defended this principle, it is scarcely an exaggeration to say that few principles in the entire history of philosophy have attracted so much distortion, misunderstanding, and misrepresentation as this. Samuel Johnson, who, we are told, upon first hearing of Berkeley's principle, kicked a stone as hard as he could, exclaiming 'I refute it thus', typifies a very common initial reaction to Berkeley, as does the sardonic humour of the poet William Cowper, who, in his poem Anti-Thelyphthora, in what is clearly a thrust at Berkeley, has the fair maid Hypothesis intone that
Substances and modes of every kind
Attention is almost invariably directed to the fact that Berkeley apparently denied the existence of the world of physical objects, despite his explicit assertions that he had no such intention. Thus, for example, in his Philosophical Commentaries (which consists of two notebooks which Berkeley kept while refining his philosophical theories, and which are invaluable for the insights which they give us into the genesis of his thought) he asserts, 'Let it not be said that I take away Existence. I only declare the meaning of the word so far as I can comprehend it.' (593).
Are mere impressions in the passive mind;
And he that splits his cranium, splits at most
A fancied head against a fancied post.
What Berkeley offers us here, then, it should be clear, is a metaphysical analysis of what it means to say that a physical object exists, an analysis which is offered quite overtly as an alternative to Aristotle's doctrine of the categories of being, and Locke's conception of the 'material substratum'. What makes his theory interesting is the fact that it is also a neo-phenomenalist reduction of physical objects into complexes of ideas, which Berkeley nonetheless believed to be commensurate with the common sense view of the nature of the physical world. Thus, for example, in his Philosophical Commentaries he writes that 'All things in the Scripture which side with the Vulgar against the learned, side with me also. I side in all things with the mob.' (405). And in a later entry he inserts a reminder to himself: 'Mem. To be eternally banishing Metaphysics, etc., and recalling men to common sense.' (751). By 'Metaphysics, etc.' in this passage Berkeley is generally understood to refer to metaphysical accounts of the nature of reality other than his own, which he quite clearly, and on the face of it astonishingly, believed to be the correct analysis of the common belief of the 'mob' on this issue.
But it is important to note in passing the precise extent to which Berkeley was both borrowing from, and reacting to, his predecessor Locke at this point. To use a crude but not entirely inappropriate metaphor, Locke held that concepts, or, as he called them, 'abstract general ideas', are related to simple ideas such as size, colour, shape, etc. as molecules are related to atoms, and consequently that such physical object concepts 'chair' and 'tree' are made up of a complex unity or 'cluster' of simple ideas of the qualities of those objects, taken in conjunction with the idea of a material substratum in which the qualities are instantiated. Yet when he tried to explicate the general idea of the underlying material substratum, Locke discovered that its very indeterminate nature emptied the putative idea of all content, and of this substratum or substance he could only say haplessly that it was 'something, he knew not what.' (Essay, 11.xxiii.2). Berkeley was not slow to observe the essential incoherence of this. For if our entire conceptual framework is derived entirely from experience, as both Locke and Berkeley believed, and material substance is indeterminate and metaphenomenal, then there can be no concept of material substance, and the assertion that such a substance or substratum exists becomes, in an empiricist frame of reference, meaningless.
However, it was only this material substratum, which, as he correctly saw it, was a philosophical conception quite foreign to the thought of the layman, that Berkeley wished to repudiate; the objective world of physical objects remains, he argues, just as real as ever. The suggestion here is that physical objects cannot be analysed in Lockean terms as complexes of qualities 'supported by' an underlying substratum; for Berkeley they are rather composites of the simple ideas acquired in perception. In short, for Berkeley a physical object is equivalent to the sum of its sensible attributes, where 'attributes' is understood to refer to ideas in the mind of the perceiver, rather than to the properties of a material substance. Thus whereas in Locke's ontology there are four kinds of irreducible entities, matter and primary qualities, and mind and ideas, in Berkeley's metaphysical schema matter disappears, and sense-qualities are assimilated with ideas. The assimilation of ideas and sense-qualities here (which was made more plausible, if not quite respectable, by Locke's ambiguously loose use of the term 'idea' in his Essay to denote both the quality of the physical object which gives rise to the perceptual experience, and the content of the perceptual experience itself) is fundamental to Berkeley's immaterialism, for, once accepted, it destroys the traditional distinction between a sensation and its intentional object. This in turn has the effect of consolidating the esse est percipi principle, for the very use of the word 'idea' as a synonym for a physical quality implies that such qualities are mind-dependent. If redness, for example, is identical with the sensation of redness, we can assign no sense to the suggestion that redness as a sensory quality continues to exist in some mode or other when it is not an actual object of sensory experience. Furthermore, the fact that Berkeley conflated qualities and ideas in this manner genuinely served to convince him of the soundness of his immaterialist hypothesis, for the Lockean contention that material substance does exist and that sense-qualities are instantiated. in it seemed to him to be equivalent to the assertion that material objects can have ideas, which, on any system of reckoning, is quite absurd (cf. Principles, 7).
For Berkeley, therefore, there are two and only two kinds of entity which possess real existence: minds or spirits and ideas. The esse or being of an idea or collection of ideas (i.e. a physical object) is to be perceived, for even if we try to conceive of some object existing unperceived, we of necessity bring that object to mind, and it cannot logically, as Berkeley puts it, exist 'out of all minds whatsoever'. (We have here, it is worth mentioning in passing, the identification of thinking with perceiving; such an identification, and the confusion of both with imagining, is fundamental to Berkeley's philosophy). Similarly, the esse of a spirit or mind is to perceive and to act; it is the fundamental reality, the only kind of substance, which thinks and wills and apprehends ideas. Because he shared Locke's view that ideas are essentially 'passive', Berkeley held that it is impossible to conceptually represent or to have an idea of spirit or mind, because, as he remarks in the Principles, 'All ideas whatever, being passive and inert, cannot represent unto us, by way of image or likeness, that which acts.' (op. cit., 27). Spirit, therefore, is for Berkeley the only substance which really exists, and he held that it fulfils all the functions which Locke had accorded to the material substratum. Berkeley's ideas, like Locke's qualities, have a dependent and relative status, in that they cannot exist autonomously, without substantial 'support', but while in the case of ideas this latter metaphor is made intelligible by being equated with perception, in the case of the Lockean material substratum it remains, and is condemned to remain, obscure and incomprehensible. (cf. Principles, 17; also First Dialogue, 199)
The hypostatisation or reification of ideas in this manner, i.e. the analysis of sensible objects into complexes of ideas, was Berkeley's chief weapon in his assault upon Locke's theory of material substance, and the position which he adopted has come to be known as 'subjective idealism'. But it should be emphasised that his procedure was to make ideas into things, not things into ideas. Thus he differentiated between what he termed 'ideas perceived by sense', (Principles, 36) i.e. sensible objects, and those ideas which have no immediate experiential source, but spring directly from the imagination. However, as with Locke, his conception of the manner in which ideas are originally formed forced him to see the difference between them merely as a qualitative one: ideas which derive from the imagination are 'faint, weak and unsteady' (ibid.), and can be summoned up or dispensed with at will, while those which we perceive by sense can not. As he puts it in the Principles
These latter are said to have more reality than the former: by which is meant that they are more affecting, orderly, and distinct, and that they are not fictions of the mind perceiving them. (Ibid.).
Thus while the esse of all ideas is to be perceived, and the ideas perceived by sense are consequently mind-dependent, they are not dependent upon any one mind, or any finite mind, at any rate, because experientially we observe that they impose themselves upon our attention, and we are accordingly forced to infer that they are functions of the operation of an external causal power.
Berkeley did not see this as a possible abrogation of his immaterialist principle, however, because for him only a spirit could be a causal agent in the literal sense of the term, hence the fact that 'ideas of the sensible world' are impressed upon our minds did not for him in the least suggest that an inference to material substance is warranted or justified. What it did suggest, and indeed, entail in his eyes, is that there is some spirit who functions as causal source or ground of our passively received ideas of the sensible world, and this argument, which is commonly known as the 'passivity argument', was Berkeley's first proof for the existence of God. (cf. McMullin, F. (ed.), 1978, p.40 ff.). This argument is articulated in a number of places in Berkeley's works, but is perhaps expressed most succinctly by him in the Principles:
But whatever power I may have over my own thoughts, I find the ideas actually perceived by sense have not a like dependence on my will. When in broad day-light I open my eyes, 'tis not in my power to choose whether I see or no, or to determine what particular objects shall present themselves to my view; and so likewise to the hearing and other senses, the ideas imprinted on them are not creatures of my will. There is therefore some other will or spirit that produces them. (105).
It should be seem immediately, however, that this argument is formally quite fallacious. For even if it is granted to Berkeley that every idea of sense is caused by a powerful spirit, as his premises assume, it does not follow that one powerful spirit causes all the ideas of sense. In other words, Berkeley was not justified in inferring Christian monotheism from the fact that our impressions or ideas of the physical world are causally imposed from 'without'; for on his own principles it is equally possible that for each idea imposed upon a given finite mind there exists a spirit who is causally responsible for putting it there. Moreover, we are justified in asking whether Berkeley's position here is really any more coherent than the Lockean view which he attacked so vigorously - in both cases the cause of the so-called ideas of sensation is itself something which lies beyond the scope of sensation, and it would seem to make little difference whether we call this unknown cause 'God' or 'matter'. It would appear that Berkeley saw this difficulty, and felt it more keenly as time went on, for while in the Principles he is content to argue that we are entitled to infer the existence of God from our recognition that we ourselves are not the causal source of our ideas of sensation, in one of his later works, Alciphron, he develops a variant of the teleological argument to the effect that the order of nature is the language or handwriting of God, and consequently that our knowledge of God, though inferential in nature, is on a par with our knowledge of finite spirits other than ourselves (op. cit., 1V.vii.12).
The important point which develops out of this, however, is that when Berkeley says that ideas are mind-dependent, he did not mean in any way to imply that the sensible world is in any way illusory, or that it is a mere collection of sense-data present in the consciousness of some mind or spirit; rather he held that everything is exactly as it appears to be, 'The horse is in the stable, the books are in the study as before' (Philosophical Commentaries, 429), but the hypothesis of an unperceivable material substratum underlying and 'supporting' such objects is totally without foundation. To say that the table exists merely means that I perceive it, and it is even possible, Berkeley affirms, for me to assert its existence when I am not actually perceiving it, 'meaning thereby that if I was in my study I might perceive it, or that some other spirit actually does perceive it'. (Principles, 3).
We do encounter here, however, a certain tension in Berkeley's thought between strict phenomenalism, which defines physical objects as 'permanent possibilities of sensation', and subjective idealism, which defines physical objects as clusters of actual sensations or ideas. To say that 'my table exists' means 'If I was in my study I might perceive it', as Berkeley does in the above passage, is to opt for the strict phenomenalist alternative, and this is incompatible both with common sense ('the mob viewpoint'), and with the esse est percipi principle. An examination of Berkeley's Philosophical Commentaries shows that he wrestled for a considerable time with both viewpoints, and saw merits in both. The idealist viewpoint attracted him because if its simplicity and logical economy. Thus, an early entry in his private journal reads 'We see the house itself, the church itself; it being an idea and nothing more. The house itself, the church itself, is an idea, i.e. an object - immediate object - of thought'. (427, 427a). However, this kind of logical economy is purchased at a substantial cost: if we identify an object with our actual perception of it, as he does here, then it follows that the object becomes as transitory, intermittent, and fragmented as the perceptions themselves. If I blink my eyes when I look at the church, it ceases to exist for an instant, to be reconstituted when my eyelids reopen. Berkeley, in the best of Irish traditions, meets this objection in the Principles in two mutually incompatible ways. For the 'learned', he advocates a form of phenomenalism: to say that a physical object exists means that it is actually perceived by someone now, or could be perceived by someone appropriately situated. For the 'mob', he has a very different, and much better-known argument: to claim that the existence of an object consists in its being perceived does not necessarily mean that it must be perceived by any particular finite mind, merely that it must be perceived by some mind, if not by a finite one, then by the infinite mind of God. Thus he asserts that 'Whatever bodies are said to have no existence without the mind, I would not be understood to mean this or that particular mind., but all minds whatsoever.' (Principles, 48). This is his idealist view - God is not only the external cause of our ideas of the sensible world, He is also the ubiquitous observer whose presence guarantees its existence.
The latter is the view expounded in Ronald Knox's famous limericks. If we accept that Berkeley took this view seriously (the issue is somewhat controversial) we find that it constitutes another proof for God's existence, which is popularly termed 'the continuity argument', i.e. the continued existence of objects which are not actually perceived by any human mind is guaranteed by the fact that they are perceived by the cosmic mind of God. Certainly Berkeley was not above making rhetorical gain out of this argument, for in the Second Dialogue Philonous is made to say
To me it is evident ... that sensible things cannot exist otherwise than in a mind or spirit. Whence I conclude, not that they have no real existence, but seeing they depend not on my thought, and have an existence distinct from being perceived by me, there must be some other mind wherein they exist. As sure therefore as the sensible world really exists, so sure is there an infinite omnipresent spirit who contains and supports it. (212).
For the sake of clarity it may perhaps be profitable at this point to summarise Berkeley's ontological theory as simply as possible. It can, in effect, be reduced to five points:
(1) The esse of sensible objects is to be perceived, and that of spirits to perceive or be conscious.
(2) What is perceived, or what we are conscious of in perception and thought, are ideas.
(3) Ideas differ from each other, in that some, which Berkeley called 'ideas of sense', are strong, vivid and involuntary, in the sense of being imposed from without, while others, 'ideas of the imagination', are weak and can be conjured up at will. The 'imposed' character of the former attests to the existence of a supreme causal agent, God.
(4) The continuous existence of physical objects which are not perceived by finite minds is explicable only by reference to the agency of a ubiquitous, cosmic mind (vulgar argument); or a physical object which is not actually perceived exists as a permanent possibility of sensation (learned argument).
(5) Finally, Berkeley is an anti-essentialist: science enhances our knowledge of phenomena not by describing the causal powers which produce the phenomena (which is properly the function of metaphysics), but by the observation of regularities in the sequence of phenomena, and by the reduction of such regularities to general rules. (cf. Principles, 105; See also Popper, K., 1968 for a detailed account of Berkeley's philosophy of science).
Stated thus, the theory's positive attributes become very evident: it is powerful and comprehensive, the product of the dialectical engagement of a brilliant and original mind with quite fundamental problems in theory of knowledge and metaphysics. It also has an aesthetic appeal which, in my view, contributes in no small way to Berkeley's high standing amongst professional philosophers today. Further, as critics have discovered to their cost., Berkeley's theory is notoriously difficult to refute. Yet Hume was surely right when he remarked of Berkeley's arguments that they 'produce no conviction' (Enquiry Concerning Human Understanding, XII.1.122n). He also said that they 'admit of no answer', but I am going to ignore his counsel in the latter respect, and in conclusion I shall attempt to show why Berkeley's arguments should produce no conviction. If I succeed I shall not have refuted Berkeley, but I shall have demonstrated that there is no reason for thinking that Berkeley's theory is true.
Let us look first at Berkeley's claim that his theory is a metaphysical expression of common sense beliefs about the nature of the physical world. Berkeley is, I believe, deviously inconsistent on the vital issue as to whether or not the common sense belief in the existence of a shared public world, in which people live and interact, is compatible with his theory. Because he saw himself as a realist championing the cause of common sense against the pernicious metaphysical obscurities of (other) philosophers, he naturally wished to be seen asserting that there is just one common world of physical objects, and that this world is perceived by all; but at the same time his most fundamental philosophical convictions precluded him from committing himself to the objective, extra-mental existence of sensible objects, independent of all perceivers. Berkeley, as one commentator puts it, was driven
by two conflicting desires: one, to oblige men to see that if there were no minds there would be nothing at all; the other, to meet the demands of common sense.' (Grave, S. A., 1968).
In actual fact, however, it is difficult to conceive of anything so far removed from the basic tenets of common sense as Berkeley's account of the sensible world. For in his system what are normally taken to be publicly observable attributes of physical objects, such as colour, size, shape, etc. become intra-mental ideas when perceived, and (on the phenomenalist reading of his theory) possibilities of sensation when not perceived. Perceived ideas are, of course, private to the particular mind which perceives them, and this destroys the possibility of a public world - so far from being compatible with common sense, Berkeley's theory is in fact inimical to it, and in its destruction of the public it demonstrates that, in common with all theories which incorporate the Cartesian view of consciousness, it is fundamentally and irrevocably solipsistic in its implications. Further, since each mode of sensory experience takes a distinct kind of idea as its intentional object, it follows from Berkeley's theory that we cannot touch what we see, or see what we hear. In short, in dispensing with material substance Berkeley removed the sole principle which, in post-Aristotelian metaphysics, unifies and integrates qualities, and was consequently left with 'free-floating' ideas, devoid of any principle of integration or unification. Thus in his Third Dialogue Berkeley has Philonous remark that 'Strictly speaking, Hylas, we do not see the same object that we feel; neither is the same object perceived by the microscope, which was by the naked eye.' (op. cit., 245).
This, of course, is the kind of viewpoint which we expect from an idealist philosopher, and Berkeley's equanimity at the collapse of the public world would be very much less surprising were he to drop his claim to 'side with the mob' in all things. But the latter is a claim which, inconsistently, he refuses to relinquish.
The upshot of my first criticism of Berkeley's theory, then, is this: not alone is it not a metaphysical expression of the common sense view of the physical world, as Berkeley implies, it is in fact incommensurate with common sense, and if we make conformity with common sense the touchstone of acceptability, as Berkeley himself urges in his First Dialogue (172), then his theory will have to be rejected out of hand. Perhaps more seriously - since not everyone would accept such a criterion of assessment - Berkeley's tacit, if unwilling, repudiation of the public places him squarely in the front rank of those philosophers whose beliefs in the primacy of the private, and mistaken assumptions concerning the putative incorrigibility of present-tense statements relating to occurrent mental states have been so greatly discredited by the work of the later Wittgenstein. It is beyond the scope of this paper to recapitulate Wittgenstein's arguments here, so I will content myself with the observation that, while it may perhaps be true (it is certainly arguable) that solipsism cannot strictly speaking be refuted, this is principally because solipsism cannot be coherently asserted in the first instance - the solipsist cannot claim to know that his words make sense without relinquishing his solipsism. (Cf. my 'Solipsism and Problem of Other Minds' in the Internet Encyclopedia of Philosophy). This is as true, in my opinion, of a theory which is implicitly solipsistic, such as Berkeley's, as it is of overt solipsism.
My second point of criticism has to do with the internal consistency of Berkeley's theory, and concerns the relationship which obtains between spirit and idea, knowing subject and known object, in his system. In asserting that the esse of an idea is to be perceived and that of spirit to perceive he was making a very clear distinction between the modes of being which pertain to the two elements in his ontology. He was also repudiating all forms of pan-psychic monism, the thesis, later to be adopted by Hegel and his followers, that everything is essentially spiritual, and that outside of spirit or mind nothing is real. In Berkeley's ontology spirit and idea are fundamentally distinct, the former being conscious, active, and volitional, the latter being passive and inert. Like Locke, Berkeley argues that ideas or sense-qualities are not substantial in themselves, and consequently that they cannot exist without the 'support' of substance. And he held that the only substance which is capable of fulfilling this task - because it is the only substance - is mind or spirit. This substance, of course, 'supports' ideas in the sense that it perceives them - this is why the esse of the latter is percipi. Consequently, a doctrine constantly reiterated by Berkeley both in the Principles and in the Dialogues is that the qualities which constitute physical objects, deprived of the impossible 'support' of material substance, have instead the 'support' of immaterial substance or mind. In short, Berkeley held that mind or spirit, unlike the material substratum of Locke, can coherently be held to 'support' qualities, in the precise sense that the metaphor of 'support' can be liberalised and explicated, in the case of mind, by identifying it with 'perception', whereas in the case of matter the metaphor remains unintelligible.
However, there is a fundamental difficulty here. To say that qualities are 'supported by' or 'instantiated in' a substance means, and can only mean, that these qualities are attributes of that substance and are therefore predicable of it. Thus a substance in which the qualities 'redness', 'extension', and 'solidity' are instantiated is, tautologically, red, extended, and solid. But while Berkeley was keen to argue that it is mind rather material substance which 'supports' qualities or ideas, he was unwilling to acknowledge that such qualities are ever attributes of mind, which is a logical consequence of this position. For he saw clearly that the acceptance of such a conclusion would have unacceptable implications for his ontology. On the one hand, it would lead to pan-psychic monism: ideas would be reduced to mere modes or attributes of mind, which would in effect encompass everything. On the other hand, a mind which had the sensations of blueness and extension would itself be blue and extended - if these were attributes of mind they would be predicable of it in precisely the same way that they are predicable of material substance in Locke's system. But it was a fundamental principle with Berkeley that the mind is incorporeal and therefore spatially non-extended, and this was a position which he consequently had to reject. Thus in the Principles he asserts that 'those qualities are in the mind only as they are perceived by it, that is, not by way of mode or attribute, but only by way of idea.' (49). However, if this latter is true then the mind cannot be related to ideas as subject to attribute, and Berkeley's original contention, that the metaphor of 'support' has a coherence when used in connection the mind which it lacks when used in connection with the Lockean substratum, collapses.
My final criticism is that Berkeley is guilty of the charge of having intellectual double standards, and of permitting his theological commitments to intrude into what purports to be a pure philosophical analysis of the nature of the physical world. As we have seen, both Locke and Berkeley were empiricists, and as such were strong advocates of the view that there is no a priori knowledge - all knowledge has its origins in experience. Despite the fact that Locke is commonly regarded as the 'father' of modern empiricism, he nevertheless persisted in his belief that a material substratum, unperceivable and unknowable, exists and functions as the 'support' for physical qualities, and Berkeley was perfectly justified in his denunciation of this view as inconsistent and incoherent. However, for Berkeley himself such philosophical niceties were of secondary importance - as we have seen, his attack on Lockean and corpuscularian materialism was motivated primarily by his conviction that it led ultimately to atheism. In this instance, of course, the philosophical and theological issues coincided: the philosophical rejection of the Lockean substratum was the first step towards immaterialism, and Berkeley's keenly analytic mind grasped this opportunity to demonstrate the anomalies and inconsistencies inherent in the materialist thesis, at least as it was outlined by Locke. However, he was at all times inclined to be less critical of issues which seemed to support his uniquely theistic world-view than he was of those to which it stood opposed, and consequently the charge of theoretical inconsistency can be as justifiably levelled at him as at Locke. For while he denied the existence of Locke's material substratum both on the grounds that, from the strict empiricist point of view, it is a metaphenomenal excrescence, and that the metaphor of 'support' which is used to convey the alleged relationship between the material substratum and the qualities instantiated in it is meaningless, he nevertheless affirmed the existence of 'spirit' or immaterial substance, which is open to precisely the same objections.
A reading of Berkeley's journal indicates that he was initially far from sure how the problem of our knowledge of mind or spirit should be approached. To begin with, his instinct seems to have been to opt for a realistic stance on this issue. Thus he writes: "We think we know not the Soul, because we have no imaginable or sensible Idea annex'd to that sound. This the Effect of prejudice.' (Philosophical Commentaries, 576). But in the very next entry, recognising, presumably, that the theory of meaning to which both he and Locke subscribed rendered any term to which an idea could not be 'annex'd' meaningless, he flatly contradicts himself: 'Certainly we do not know it. This will be plain if we examine what we mean by the word knowledge.' (576a). And he goes on to develop this latter viewpoint, outlining in the process a phenomenalist account of mind which is identical in every important respect with the version subsequently adumbrated by Hume:
The very existence of Ideas constitutes the soul ... Consult, ransack your Understanding. What find you there besides several perceptions or thoughts? What mean you by the word mind? You must mean something that you perceive or that you do not perceive. A thing not perceived is a contradiction. To mean (also) a thing you do not perceive is a contradiction. We are all in this matter strangely abused by words. Mind is a congeries of Perceptions. Take away Perceptions & you take away the Mind. Put the Perceptions and you put the mind. (Ibid., 577-580).
This would seem to be Berkeley's considered view; it is certainly the view which his empiricist theories of knowledge and meaning logically entail. But in the works which he wrote for publication, and in particular in the Third Dialogue, he adopts a very different position. With an intellectual sleight of hand which is a dazzling as it is reprehensible, he shifts the basis for the repudiation of matter: 'I do not deny the existence of material substance, merely because I have no notion of it, but because the notion of it is inconsistent, or in other words, because it is repugnant that there should be a notion of it.' (op. cit., 232). This allows him to argue that the concept of mind or spirit is not inconsistent or incoherent in this sense, and that we do in fact have a 'notion', though not an idea, of mind or spirit. The grounds offered for this latter affirmation bring out quite clearly the extent to which Berkeley's position here is at variance with his epistemological commitments:
I know or am conscious of my own being; and that I myself am not my ideas, but somewhat else, a thinking active principle that perceives, knows, wills, and operates about ideas. I know that I, one and the same self, perceives both colours and sounds: that a colour cannot perceive a sound, or a sound a colour: that I am therefore one individual principle, distinct from colour and sound; and, for the same reason, from all other sensible things and inert ideas. (Ibid., 234).
This implies that the mind or spirit is discriminated from ideas by the very process of abstraction which Berkeley attacks so fiercely in his Introduction to The Principles, and indeed it should have been a matter of no small intellectual embarrassment to him, given his castigation of Locke's characterisation of material substance as an indeterminate 'something', that his own specification of the nature of mind should be equally vacuous. Nor is his argument that it is possible to have a 'notion' of mind, which, though lacking the status of an idea, is nonetheless not empty, particularly convincing - it presumably could equally well be argued that we have a 'notion', though not an idea, of material substance.
Berkeley, in my view, was fully aware of his theoretical inconsistency here - the starkness of the contrast between the phenomenalist analysis of mind in the Commentaries and the views expressed in his published works bears eloquent testimony to this - but he simply could not bring himself to publicly advocate phenomenalism, entirely because the theological implications of such a reductionist account of mind were unpalatable to him. Consequently, it was left to his successor Hume, who suffered no such compunctions, to take the final step in the dialectical movement away from the Cartesian account of the nature of reality, by denying the existence of material and immaterial substance alike. There is a deep philosophical irony here - the central thrust of Berkeley's philosophical work was determined by his desire to impede the development of philosophical positivism and scepticism, the seeds of which he had discerned in the materialism of Locke. Yet in the final analysis his immaterialist ontology, resting as it does upon his skilful (if selective) employment of Ockham's razor in the field of genetic epistemology, was to constitute a major step in the development of the positivism which he so abhorred. From this, in my view, an incalculably valuable general precept may be adduced: the conceptual bi-polarity of idealism and positivism is, or can be, misleading in the extreme - the movement from the former to the latter which we encounter when we turn from Berkeley to Hume is indicative of the true practical proximity of the two positions. Berkeley's deservedly high standing with professional philosophers today is due to no small degree to the fact that we can learn such fundamental lessons from his work.