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INSTITUTES OF METAPHYSIC.
PROP. XVII.————
of reason; and consequently the counter-proposition is an affirmation which contradicts a necessary truth of reason. Thus it involves a mental contradiction, whether looked at in its negative or in its affirmative aspect
The counter-proposition considered in so far as it is the product of natural thinking.5. Secondly, We have now to consider what part of the counter-proposition stands opposed to the proposition as the product of natural, and not of psychological, thinking. It is sometimes difficult to determine what is a spontaneous mode, and what is an acquired habit, of thought, because psychological doctrine frequently mingles its contaminating waters with the not over-clear current of popular thinking, until men imagine that they are entertaining naturally, and of their own accord, some dogma for which they were indebted to a perverse training in what is called "mental philosophy." In the present instance, however, it is not difficult to distinguish the natural from the psychological judgment Psychology tries to persuade people that in all their dealings with themselves and the universe, they never come across anything substantial—that mere qualities or phenomena are the objects of their contemplation. But the world has not been imposed upon by this consecrated nonsense, against which it is unnecessary to argue; for, let psychologists preach, and let their followers believe as they will, it is certain