The philosophical revolution begun by Descartes was to be completed by Berkeley and Hume.  Descartes had reduced reality to thought with his statement, "I think therefore I am (cogito ergo sum)," but he did not take this idea to its logical conclusion.  Berkeley and Hume continued along the main line of Descartes reasoning reducing reality even further, turning it into a form of subjectivist idealism, and in the case of Hume ultimately to a denial even of the notion of the subject or person itself.  This subjectivist quality is what distinguishes the idealism of Plato from that of the idealism of the Cartesian revolution, because Plato's Ideas subsist independently of any mind, even independently of the mind of the Demiurge.

          Berkeley's position can be divided into five main points, which I will now present, but in an order that is slightly different from his own.  He begins by defining reality as ideas which exist in the mind, he states that ". . . the objects of human knowledge . . . 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" [Berkeley, Of the Principles of Human Knowledge, #1].  So for Berkeley an apple is a "collection of ideas" which "are accounted one distinct thing" [Berkeley, Of the Principles of Human Knowledge, #2], thus an apple does not subsist independently of the mind perceiving it.

          The second point concerns the fact that these ideas are perceived by a subject, a living being, what Berkeley calls a mind, spirit, soul, or self.  Since the ideas are reality, their existence simply consists in being perceived; in other words, existence or being is perception (esse est percipi) [cf. Berkeley, Of the Principles of Human Knowledge, #2, #3].  Based upon what has been said so far, for Berkeley there can only be ideas if there is perception, and for there to be perception, there must be a perceiving agent.  Thus Berkeley says, "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, viz., 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" [Berkeley, Of the Principles of Human Knowledge, #6].  

          This brings us to Berkeley's third point, which deals with the notion of the soul or self.  Berkeley asserts that the soul or spirit is "one simple, undivided, active being" [Berkeley, Of the Principles of Human Knowledge, #27], and that because the soul is active, as both understanding and will, it cannot be an idea itself, because ideas are passive and lack motion.  This presents a problem in his system, a problem which he resolves by saying that the word soul does not stand "for any idea at all . . ." but at the same time we do "have some notion of soul, spirit, and the operations of the mind" [Berkeley, Of the Principles of Human Knowledge, #27].

          His fourth point deals with his denial of the concept of matter.  Because of Berkeley's assertion that only ideas are real, and that ideas must be perceived, it follows that matter, which is "an inert, senseless substance, in which extension, figure, and motion . . . actually subsist" [Berkeley, Of the Principles of Human Knowledge, #9], involves a logical contradiction.  Since extension, figure, and motion are all ideas in the mind it is impossible for them to exist in a substance which is incapable of perception, thus matter is – for Berkeley – a fiction.  His fifth and final point is connected to his faith in God; since being is perception, it is necessary that there be some spiritual being which constantly perceives things so that existence is continuous, this being or Spirit is God.

          Hume takes the Cartesian revolution to its logical conclusion, he completes the reduction of reality to thought and in this way eliminates the concept of spiritual substance which Berkeley wanted to keep.  Hume's system is more complex than that of Berkeley and thus more difficult to relate in a brief synopsis, so this portion of the paper will necessarily be a cursory overview of his theory.  Hume divides perception into what he calls impressions and ideas.  Impressions strike the mind more powerfully, while ideas are weaker and have less impact.  He further divides these perceptions into simple and complex concepts.  He next points out that our impressions and ideas possess a resemblance to each other, and that they differ only in "their degree of force and vivacity" [Hume, Sect. 1, Of the Origin of our Ideas, Para. 3], as Hume sees it, all of the mind's perceptions are dualistic, with the ideas being ". . . exact representations of the impressions" [Hume, Sect. 1, Of the Origin of our Ideas, Para. 3].  Hume's theory uses a more complex terminology than his predecessor, and clearly rejects the spiritual elements still present in Berkeley's system.  Nevertheless, Hume agrees with Berkeley in rejecting material substance, while also rejecting the idea of immaterial substance, for as he explains, "The idea of substance as well as that of a mode, [are] nothing but a collection of simple ideas, that are united by the imagination, and have a particular name assigned to them, by which we are able to recall, either to ourselves or others, that collection" [Hume, Sect. 6, Of Modes and Substance, Para. 2].

          Thus the idea of substance – in general – is arbitrary, in that we assign qualities to a thing and say that they inhere in the substance of the thing, but since substance is neither an impression nor an idea, it is not real and thus there is no such thing as substance, whether conceived of as material or immaterial.  In doing this Hume moves beyond Berkeley since he holds that what is true for material substance would also hold in connection with immaterial substance.  As a consequence of this, Hume also denies the very notion of a self, and in doing this he is more consistent than Berkeley.  The notion of the self is an illusion, as Hume says, ". . . we feign the continued existence of the perceptions of our senses, to remove the interruptions:  and run into the notion of a soul, and self, and substance, to disguise the variation" [Hume, Sect. 6, Of Personal Identity, Para. 6].

          My response to the philosophical theories of Berkeley and Hume will be brief and I will concentrate initially on the element within their systems which I find most problematic, i.e., their subjectivistic idealism; and in conclusion I will briefly respond to Hume's denial of the self.  They both follow Descartes with his reduction of reality to thought, and this presupposition is the weakness in both of their systems.  Their systems are completely subjective and this distinguishes them from the idealism of Plato; in Plato's system, as I mentioned earlier, the Ideas or Forms subsist independently of any mind.  This gives an objective quality to his system, which provides a more solid basis for understanding reality.  The philosophical systems of Berkeley and Hume only work if you accept the presupposition that reality is merely ideas, or in the case of Hume, ideas and impressions.  Their denial of substance follows naturally from their viewing reality as thought, but as a professor of mine once said, if idealism is true, why is the world not an ideal place?  Why is it filled with pain and suffering?  If the world is made up of ideas alone, then let the idealist kick a concrete barrier; for if he is right, he should feel no pain.

          As far as Hume's denial of the self is concerned, his view is not new, it is merely a more modern version of the theories of Heraclitus and the Buddha.  The problem of being and becoming was nicely resolved by Aristotle through the principles of act and potency.  The human person is a being in act (i.e., actually existing), but with the potency (i.e., a potentiality) for further perfections, thus Aristotle's philosophy reconciles the fact of stability and with the fact of change.  His system, unlike the Cartesian idealistic theory, accounts for the stability of beings and for the fact that they do undergo change with time, but then Aristotle was a realist.  This briefly expresses some of my concerns about the systems of Berkeley and Hume, it is in no way an exhaustive study, because that would require that I write a much longer essay, and my essay is already too long.

BIBLIOGRAPHY

George Berkeley.  A Treatise Concerning the Principles of Human Knowledge.  (Philadephia:  J. B. Lippincott and Company, 1874).

          Edited and translated by Charles P. Krauth.

David Hume.  A Treatise of Human Nature. (London:  Longmans, Green, and Company, 1874).  2 Volumes.

          Edited by T. H. Green and T. H. Grose.

Berkeley and Hume

by Steven Todd Kaster

San Francisco State University

Philosophy 457:  The Nature of the Self

Professor Georgia Bassen

17 October 2000

Copyright © 2000-2025 Steven Todd Kaster