378 ON THE HYPOTHESIS 



the three combatants are very little more in harmony with themselves than 

 they are with the Goliath against whom they have entered the lists. There 

 is a fourth objection, however, and it would be the chief and most direct, if 

 it could be well supported, on which the metaphysicians of the north seem 

 to be unanimous. The Essay on Human Understanding resolves all the ideas 

 we possess, or can possibly possess, into the two classes of those obtained by 

 sensation, or the exercise of our external senses, and those obtained by re- 

 flection, or the operations of the mind on itself; and it defies its readers to 

 point out a single idea which is not reducible to the one or the other of these 

 general heads. The supporters of the northern hypothesis have specially 

 accepted this challenge, and have attempted to 'point out a variety of ideas, or 

 CONCEPTIONS, as Dr. Reid prefers calling them, which are in the mind of every 

 man, and which are neither the result of sensation or reflection ; and they 

 have peculiarly fixed upon those of extension, figure, and motion. And 

 hence this argument is regarded as decisive, and is proposed, both by Dr. 

 Reid and Prefessor Stewart, "as an experimentum crucis, by which the ideal 

 system must stand or fall."* 



Now, strictly speaking, this invincible argument, as it is called, is no argu- 

 ment whatever. It is a mere question of opinion, whether the above-named 

 ideas, together with those of time, space, immensity, and eternity, which 

 belong to the same class, can be obtained either by means of the external 

 senses or the operation of the mind upon its own powers, or whether they 

 cannot. And, for myself, I completely concur in believing with Mr. Locke 

 that they can : though I am ready to leave this part of the subject, as I am 

 the whole question between us, to Mr. Stewart's own case of the boy born 

 blind and deaf, as communicated to the Royal Society of Edinburgh in the 

 course of last year ;f who, it is admitted, is possessed of perfect soundness 

 of mind ; but who, at that time in his seventeenth year, was, as we are ex- 

 pressly told, without any idea of a being superior to himself ; of any religious 

 feelings ; and who did not appear to have possessed any moral feelings upon 

 the sudden death of an indulgent father, notwithstanding the utmost pains 

 that had been taken to give him instruction. If this boy shall be found to 

 possess as clear an idea of figure and motion as those who have the free' use 

 of their eyes, I will readily allow Mr. Locke's system to be unfounded. That 

 he must have some idea follows necessarily from this system; because he 

 appears to have a very fine touch, and has also, or at least had till very lately, 

 some small glimmering of light and colours.J 



But, upon the northern hypothesis, he ought not only to have some idea of 

 these qualities of bodies, but A MOST TRUE AND CORRECT IDEA, probably more so, 

 instead of less so, than that of other persons : since he is said to obtain it 

 from a faculty which is not supposed to be injured, and since the want of one 

 sense is usually found to strengthen the remainder. 



With respect to the idea of extension, indeed, which, by some philosophers, 

 is thought to be the most difficult of the whole, it appears to me that it is 

 capable of being obtained with at least as much perspicuity as that of most 

 other qualities of bodies, and more so than ideas of many of them ; for we 

 have in this instance the power of touch to correct that of sight, or vice versd; 

 while in a multitude of other instances we are compelled to trust to one sense 

 alone. Extension, in its general signification, is a complex idea, resulting 

 from a combination of the more simple ideas of length, breadth, and thick* 

 ness ; and hence evidently imports a continuity of the parts of whatever sub- 

 ject the idea is applied to ; whether it be a solid substance, as a billiard ball, 

 or the unsolid space which measures the distance between one billiard ball 

 and another; the idea of measure being, indeed, the most obvious idea we can 

 form of it. In both which cases we determine the relative proportions i>f the 



* Ufid's Inquiry, &c. p. 137. Stewart's Essays, vol. i. p. 549. 



f "Some Account of a Hoy born Blind and 'Deaf. Ry Dngald Stewart, Esq., F.R.S.," ed. 4to. Edin. 

 1812. With which compare, relating to the s=ame individual, "History of James Mitche . a Boy born 

 Blind and Deaf, &c. By James Wardrop, F.R.S." Ed. 4to. 1813. 



J See Edin. Rev. No. xl. p. 468. 



