_First_, We shall reply to Descartes, it is not a warrantable deduction, that because we have an idea of a thing, we must therefore conclude it exists; to give validity to such a mode of reasoning would be productive of the greatest mischief; would, in fact, tend to subvert all human institutions. Our imagination presents us with the idea of a sphinx, or of an hippogriff, besides a thousand other fantastical beings; are we, on that authority, to insist that these things really exist? Is the mere circumstance of our having an idea of various parts of nature, discrepantly jumbled together, without any other evidence as to the assemblage, a sufficient warrantry for calling upon mankind to accredit the existence of such heterogeneous masses? If a philosopher of the most consummate experience, of the greatest celebrity, one who enjoyed the confidence of mankind above every other, was to detail the faculties and perfections of these visionary beings, although he should hold them forth as the perfection of all natural combinations, would, I say, any reasonable being lend himself to the asseveration?
_Secondly_, It is obvious that the mere circumstance of existence, does not prove the absolute existence of any thing anterior to itself; although in man, as well as the other beings of nature, it is evidence that something has existed before him. If this argument was to be admitted, are they aware how far it, would carry them? To maintain that the existence of one being demonstrably proves the existence of an anterior being, would be, in fact, denying that any thing was self-existent. The fallacy of such a position is too glaring to need refutation.
_Thirdly_, It is not possible he should have a distinct, positive idea of immateriality, of which be, as well as the theologian, labours to prove the existence. It is impossible for man, for a material being, to form to himself a correct idea, or indeed any idea, of incorporeity; of a substance without extent, acting upon nature, which is corporeal; a truth which it may not be presuming too much to say we have already sufficiently proved.
_Fourthly_, It is equally impossible for man to have any clear, decided idea of perfection, of infinity, of immensity, and other theological attributes. To Descartes we must therefore reply as we have done to Dr. Clarke on his twelfth proposition.