Berkeley would be blocked; to be an idea in the mind would not involve lack of cognitive and representative value in that idea. The fact that material objects were represented or conceived would not of itself prove that they could not have a real existence. It would be necessary, to prove their unreality, to study their nature and function and to compare them with such conceptions as those of Providence and a spirit-world in order to determine their relative validity. Such a critical comparison would have augured ill for Berkeley’s prejudices; what its result might have been we can see in Kant’s Critique of Pure Reason. In order to escape such evil omens and prevent the collapse of his mystical paradoxes, Berkeley keeps in reserve a much more insidious weapon, the sceptical doubt as to the representative character of anything mental, the possible illusiveness of all knowledge. This doubt he invokes in all those turns of thought and phrase in which he suggests that if an idea is in the mind it cannot have its counterpart elsewhere, and that a given cognition exhausts and contains its object. There are, then, two separate maxims in his philosophy, one held consistently, viz., that nothing can be known which is different in character or nature from the object present to the thinking mind; the other, held incidentally and inconsistently, since it is destructive of all predication and knowledge, viz., that nothing can exist beyond the mind which is similar in nature or character to the “ideas” within it; or, to put the same thing in other words, that nothing can be revealed by an idea which is different from that idea in point of existence. The first maxim does not contradict the existence of external objects in space; the second contradicts every conception that the human mind can ever form, the most airy no less than the grossest. No idealist can go so far as to deny that his memory represents his past experience by inward similarity and conscious intention, or, if he prefers this language, that the moments or aspects of the divine mind represent one another and their general system. Else the idealist’s philosophy itself would be an insignificant and momentary illusion.
