Holy Cyclops

St. Anselm of Canterbury (1033-1109) was a monk and theologian who, in his Proslogion, gave an argument for the existence of God on the basis of the definition of God—i.e., on the basis of what it would mean to be  God.  The argument is fatally flawed and should convince no one, but, somewhat surprisingly, it has supporters even to this day.  St. Anselm’s ontological argument for the existence of God runs about like this:  (1)  God is that greater than which none can be conceived; (2)  an existent God would be greater than a nonexistent God; (3) if God did not exist, then something greater could be conceived—namely, a God that did exist; (4)  therefore, God exists.

Although it is possible to analyze this argument in some detail, I’ll just give the main problem here.  The argument fails to distinguish between an object or entity  and the mental conception of an object or entity.  (A lion wandering the African savannah isn’t the same as my mental conception of it; the former is a solid object, while the latter is only an idea.)  It might be that an object God would be greater than its mental conception, or that it would be greater for both the object God to exist and the mental conception of God to be conceived than it would be for the mental conception of God to be conceived without the object God’s existing; but the conception of God may be the greatest conceivable either way.  The object God’s existence or nonexistence doesn’t affect its mental conception’s being the greatest possible mental conception.  (Had St. Anselm argued that the conception of God is the greatest conceivable mental conception, and that the conception of God as existent would be greater than the conception of God as nonexistent, so that the conception of God must be conceived as existent, I’d've had no problem with the argument—but it wouldn’t have established God’s existence.  I conceive of Pegasus as winged, as maned, as white, as solid, as physical—as existent—but I do not thereby bring Pegasus into existence; and I may conceive of Pegasus as giving a ride to my nephew instead of to Bellerophon—I may conceive of Pegasus as nonfictional rather than as fictional—but, again, I do not thereby bring Pegasus into existence.  Conceiving of God as existent is not the same as affirming God’s existence; neither being conceived of as having existence-implying properties nor being conceived of as nonfictional implies actual existence.)

Even the language of the argument is deceptive.  One conceives  mental conceptions, but conceives of  objects; as phrased, the argument has the object God conceived.  Paying proper attention to the difference between existing  and being conceived of  makes that problem go away, but it also completely nullifies the argument.  “God is that entity whose mental conception is the greatest possible,” together with, “An existent God is greater than its mental conception,” doesn’t lead to a contradiction if God is assumed not to exist.