as a prominent recognition of the new doctrine in France, within thirty years from its first promulgation: 'Il faut absolument conclure de tout ceci, que les distances, les grandeurs, les situations ne sont pas, à proprement parler, des choses visibles, c'est à dire, ne sont pas les objets propres et immédiats de la vue. L'objet propre et immédiat de la vue n'est autre chose que la lumière colorée: tout le reste, nous ne sentons qu'a la longue et par expérience. Nous apprenons à voir, precisement comme nons apprenons à parler et à lire. La difference est, que l'art de voir est plus facile, et que la nature est egalement à tous notre maître. 'Les jugemens soudains, presque uniformes, que toutes nos âmes, à un certain age, portes des distances, des grandeurs, des situations, nous font penser, qu'il n'y à qu'à ouvir les yeux, pour voir la manière dons nous les voyons. On se trompe; il est faut les secours des autres choses. Si les hommes n'avoient que le sens de la vue, ils n'auroient aucun moyen pour connaitre l'étendue en longueur, largeur et profondeur; et un pur esprit ne la connoîtroit peut-etre, a moins que Dieu ne la lui révélât. Il est très difficile de separer dans notre entendement l'extension d'un objet d'avec les couleurs de cet objet. Nous ne voyons jamais rien que d'étendu, et de-là nous sommes toutes portés à croire, que nous voyons en esset l'étendue.' (Elemens de la Philos. de Newton, Second Partie, ch. 5.) Condillac, in his Essais sur l'Origine des Comnaissances Humanes (Part I. sect. 6), published in 1746, combats Berkeley's New Theory, and maintains that an extension exterior to the eye is discernible by sight, the eye being naturally capable of judging of figures, magnitudes, situations, and distances. His reasonings in support of this 'prejudice,' as he afterwards allowed it to be, may be found at length, in the section entitled 'De quelques jugemens qu'on a attribués à l'ame, sans fondement, ou solution d'un problême de métaphysique.' Here Locke, Molyneux, Berkeley, and Voltaire are criticised, and Cheselden's experiment is referred to. Condillac's subsequent recantation is contained in his Traité des Sensations, published in 1754, and in his L'Art de Penser. In the Traité des Sensations (Troisieme Partie, ch. 3, 4, 5, 6, 7, 8, &c.) the whole question is discussed at length, and Condillac vindicates what he allows must appear a marvellous paradox to the uninitiated—that we gradually learn to see, hear, smell, taste, and touch. He argues in particular that the eye cannot originally perceive an extension that is beyond itself, and that the notion of trinal space is due to what we experience in touch. Voltaire and Condillac gave currency to the New Theory in France, and it soon became a commonplace with D'Alembert, Diderot, Buffon and other French philosophers. In Germany we have allusions to it in the Berlin Memoirs and elsewhere; but, although well known by name, if not in its distinctive principle and latent idealism, it has not there obtained the consideration which its author's fully developed theory of matter has received. The Kantian account of Space, and of the origin of our mathematical notions, may have subsequently indisposed the German mind to the a posteriori reasoning of Berkeley's Essay. Its influence is most apparent in British philosophy. The following passages in Hartley's Observations on Man, published in 1749, illustrate the extent to which some of the distinctive parts of Berkeley's doctrine were at that time received by an eminent English psychologist: 'Distance is judged of by the quantity of motion, and figure by the relative quantity of distance. . . . And, as the sense of sight is much more extensive and expedite than feeling, we judge of tangible qualities chiefly by sight, which therefore may be considered, agreeably to Bishop Berkeley's remark, as a philosophical language for the ideas of feeling; being, for the most part, an adequate representative of them, and a language common to all mankind, and in which they all agree very nearly, after a moderate degree of experience. However, if the informations from touch and sight disagree at any time, we are always to depend upon touch, as that which, according to the usual ways of speaking upon these subjects, is the true representation of the essential properties, i. e. as the earnest and presage of what other tangible impressions the body under consideration will make upon our feeling in other circumstances; also what changes it will produce in other bodies; of which again we are to determine by our feeling, if the visual language should not happen to correspond to it exactly. And it is from this difference that we call the touch the reality, light the representative—also that a person born blind may foretell with certainty, from his present tangible impressions, what others would follow upon varying the circumstances; whereas, if we could suppose a person to be born without feeling, and to arrive at man's estate, he could not, from his present visible impressions, judge what others would follow upon varying the circumstances. Thus the picture of a knife, drawn so well as to deceive his eye, would not, when applied to another body, produce the same change of visible impressions as a real knife does, when it separates the parts of the body through which it passes. But the touch is not liable to these deceptions. As it is therefore the fundamental source of information in respect of the essential properties of matter, it may be considered as our first and principal key to the knowledge of the external world.' (Prop. 30.) In other passages of Hartley's work (e. g. Prop. 58) the relation of our visual judgments of magnitude, figure, motion, distance, and position, to the doctrine of association is explained, and the associated circumstances by which these judgments are formed are enumerated in detail. Dr. Porterfield of Edinburgh, in his Treatise on the Eye, the Manner and Phenomena of Vision (Edinburgh 1759), is an exception to the consent which the doctrine had then widely secured. He maintains, in opposition to Berkeley, that 'the judgments we form of objects being placed without the eye, in those perpendicular lines, or, which is nearly the same thing, the judgments we form of the situation and distance of visual objects, depend not on custom and experience, but on original, connate, and immutable law, to which our minds have been subjected from the time they were at first united to their bodies."* Berkeley's Theory of Vision, in so far as it resolves our supposed visual perceptions of distance into an interpretation of suggestive signs, received the qualified approbation of Dr. Reid, in his Inquiry into the Human Mind on the Principles of Common Sense (1764). He criticises it in detail in successive chapters of the Inquiry, where the doctrine of arbitrary, natural signs, of which Berkeley's philosophy is the development, is accepted, and to some extent applied. With Reid it is divorced, however, from the Berkeleian metaphysics as a whole, although the Theory of Vision was the seminal principle of Berkeley's Theory of Matter.+ Berkeley's Theory of Matter was an object of professed hostility to Reid and his followers, while his Theory of Vision has obtained the almost unanimous consent of the Scotch metaphysicians. Adam Smith refers to it in his Essays (published in 1795) as 'one of the finest examples of philosophical analysis that is to be found either in our own or in any other language.' Mr. Stewart characterises it in his Elements, which had appeared three years before, as one of the most beautiful, and at the same time one of the most important theories of modern philosophy.' 'The solid additions,' he afterwards remarks in his Dissertation, made by Berkeley to the stock of human knowledge, were important and brilliant. Among these the first place is unquestionably due to his New Theory of Vision, a work abounding with ideas so different from those commonly received, and at the same time so profound and refined, that it was regarded by all but a few accustomed to deep *See Treatise on the Eye, Vol. II. pp. 299, &c. +See Reid's Inquiry, Ch. v. §§ 3, 5, 6, 7; Ch. vi. § 24, and Essays on the Intellectual metaphysical reflection, rather in the light of a philosophical romance than of a sober inquiry after truth. Such, however, has since been the progress and diffusion of this sort of knowledge, that the leading and most abstracted doctrines contained in it form now an essential part of every elementary treatise on optics, and are adopted by the most superficial smatterers in science as fundamental articles of their faith.' The New Theory is accepted by Dr. Thomas Brown, who proposes (Lectures, 29) to extend its reasonings to more refined conclusions. With regard to the perceptions of sight, Dr. John Young, in his Lectures on Intellectual Philosophy (p. 102), says that it has been universally admitted, at least since the days of Berkeley, that many of those which appear to us at present to be instantaneous and primitive, can yet be shewn to be acquired; that at least most of the perceptions of sight are founded on the previous information of touch;-that colour, considered as a mere sensation of the mind, can give us no conception originally of those qualities of bodies which produce it in us; and that primary vision gives us no notion of distance, nor of true relative magnitude, and, as I believe, no notion of magnitude at all. Most certainly, at least, it can give us no notion primarily of resistance, solidity, roughness and smoothness, in bodies; and yet these are among the chief elementary notions which we have of matter.' Sir James Mackintosh, in his Dissertation, characterises the New Theory of Vision as a great discovery in Mental Philosophy.' 'Nothing in the compass of inductive reasoning,' remarks Sir William Hamilton (Reid's Works, p. 182, note), 'appears more satisfactory than Berkeley's demonstration of the necessity and manner of our learning, by a slow process of observation and comparison alone, the connexion between the perceptions of vision and touch, and, in general, all that relates to the distance and real magnitude of external things.' 'With regard to the method by which we judge of distance, it was formerly,' he tells us in his Lectures on Metaphysics (XXVIII), supposed to depend upon an original law of the constitution, and to be independent of any knowledge gained through the medium of the external senses. This opinion was attacked by Berkeley in his New Theory of Vision, in which it appears most clearly demonstrated that our whole information on this subject is acquired by experience and association.'* *While Sir W. Hamilton acknowledges the scientific validity of Berkeley's conclusions, as to the way we judge of distances in seeing, he curiously complains, in the same lecture, that the whole question is thrown into doubt by the analogy of the lower animals,' i. e. by their probable visual instinct of distances; and elsewhere (Reid's Works, p. 137, note) he seems to hesitate about Locke's Solution of Molyneux's Problem, at least in its application to Cheselden's case. Cf. Leibnitz, Nouveaux Essais, Liv. II. ch. 9. It is worthy of remark that the New Theory has been generally accepted, so far as it was understood, alike by the followers of Hartley and by the associates and successors of Reid. Among British psychologists, it has recommended itself to metaphysical rationalists and sensationalists, to the advocates of innate principles, and to those who would explain, by the laws of mental association, what their rivals attribute to the absolute constitution of intelligence. This one doctrine, as Mr. J. S. Mill remarks, has been recognised and upheld with singular unanimity by the leaders of all schools of philosophical thought.* It may thus be fairly adduced as an example of an acknowledged discovery in metaphysics; while a careful study of its nature and evidence is among the best metaphysical exercises of the refined thought and exact use of words in which mental analysis is the only adequate education. A. C. F. As almost solitary exceptions to this unusual uniformity of profession on a subtle question in psychology, I may refer to two works, which are valuable at least as much for the criticism they have occasioned as for their contents. In 1842 Mr. Samuel Bailey of Sheffield, a candid and able inquirer, published a Review of Berkeley's Theory of Vision, designed to show the unsoundness of that celebrated Speculation. Mr. Bailey's book recalled attention, at the time of its appearance, to the basis in consciousness on which the theory rests. It was the subject of two interesting rejoinders—a well-weighed criticism, in the Westminster Review, by Mr. J. S. Mill, since republished in his Discus sions; and an ingenious Essay by the late Professor Ferrier, in Blackwood's Magazine, now republished in his Philosophical Remains. The controversy ended on that occasion with Mr. Bailey's Letter to a Philosopher in reply to some recent attempts to vindicate Berkeley's Theory of Vision, and in further elucidation of its unsoundness, and a reply to it by each of his critics. It was revived in 1864 by Mr. Abbott of Trinity College, Dublin, who produced his Sight and Touch, as an attempt to disprove the received (or Berkleian) Theory of Vision,' but he seems to have overlooked the nature of the Theory which he professes to disprove. |