LETTER TO SIR W. HAMILTON.
(Not Sent)
St Andrews, 18th Oct. 1851.
My dear Sir William,—There is an ambiguity or inconsistency in your doctrine of "presentative knowledge" which I have often intended to speak to you about, and request an explanation of. You say, Reid, p. 805, "In a presentative or immediate cognition there is one sole object." What is this one sole object? Our organism, you answer. From which it of course follows that everything beyond our organism is a mediate object of cognition. This is indeed expressly admitted. "The primary qualities of things external to our organism we do not perceive—i.e., immediately know," p. 881. And yet, in the face of that statement, I read, p. 810, "The primary qualities of matter or body, new and here—that is, in proximate relation to our organs—are objects of immediate cognition to the natural realists." These two statements are absolutely contradictory and irreconcilable. Of course, the primary qualities, when "in proximate
