SIR WILLIAM Hamilton's philosophy. 385 



doubt the actuality of a fact of consciousness without doubting, that 

 is subverting our doubt itself."* Now, in an act of perception, as in 

 any other act, it is certainly impossible to doubt the fact that I am 

 conscious of something ; but what that something is of which I am 

 conscious, is not in the same category of indubitable certainty at all. 

 On the contrary I believe that not only in the case of external percep- 

 tion, but very frequently also ia regard to other states of consciousness the 

 point most difficult of determination is precisely the fact which con- 

 sciousness really attests. This is a difficulty which is met not only in 

 reflecting on the phenomena of mind, but also in observing the phe- 

 nomena of matter ; and Hamilton himself inculcates the caution which 

 the difficulty renders necessary. In explaining the conditions of a le- 

 gitimate hypothesis he lays down as the very first, that the phenom- 

 ena,. which the hypothesis explains, should be ascertained actually to 

 exist ; and lest the condition should appear too elementary to be 

 worthy of statement, he warns his students that the necessity of the 

 admonition is shown by " great and numerous examples of its violation 

 in the history of science," quoting with approbation the remark of 

 Cullen, " that there are more false facts current in the world than 

 false hypotheses to explain them."t While the observation of physi- 

 cal phenomena is not unattended with risks that require the observer 

 to guard himself by numerous precautionary measures, the difficulty 

 of making exact observations so as to distinguish facts from mere illu- 

 sory appearances Hamilton himself describes as immeasurably increased 

 in seeking to detect the phenomena of consciousness. It is indeed one 

 of his charges against the hypothesis of representative perception, that 

 it fails to fulfil the above-mentioned condition of a legitimate hypoth- 

 esis ;| and not the least frequent criticism which he passes on theories 

 opposed to his own is to the effect, that they mis-state the facts to be 

 explained in order to suit their explanation. I hold therefore that a 

 principle, not only prejudicial to science, but opposed to the explicit 

 teaching of Hamilton himself, would be introduced by the doctrine, 

 that it is impossible for any one to doubt what, at any conscious mo- 

 ment, the fact is, to which consciousness actually testifies and in which 

 accordingly its veracity is involved. It is not therefore legitimate in 

 Sir William Hamilton to assert that the fact of consciousness, as in- 



* Reid's Works, p. 744. The itali are his own. 

 ■j- Led. on Metaph., Vol. I., p. 169 

 tlbid., Vol. II. p. 138. 



