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point, Descartes discovers that he has an idea of perfection. He
then argues that such an idea implies a cause. However, the thing
that caused it must have as much `reality, and that includes perfection, as the idea itself. This implies that only a perfect cause, that is,
God, will do. Hence God exists, and has left the idea of perfection
as an innate sign of his workmanship in our minds, like a craftsman leaving a trademark stamped in his work.
    Once Descartes has discovered God, the seas of doubt subside in
a rush. For since God is perfect, he is no deceiver: deceiving is
clearly falling short of goodness, let alone perfection. Hence, if we
do our stuff properly, we can be sure that we will not be the victims
of illusion. The world will be as we understand it to be. Doing our
stuff properly mainly means trusting only clear and distinct ideas.
    What are we to make of the `trademark' argument? Here is a reconstruction:
    I have the idea of a perfect being. This idea must have a
cause. A cause must be at least as perfect as its effect. So
something at least as perfect as my idea caused it. Therefore
such a thing exists. But that thing must be perfect, that is, God.
    Suppose we grant Descartes the idea mentioned in the first
premise. (There are theological traditions that would not even do
that. They would say that God's perfection defies understanding,
so that we have no idea of it, or him.) Still, why is he entitled to the premise that his idea must have a cause? Might not there be events
that have simply no cause? Events that, as we might say, `just happen'? After all, sitting on his rock, Descartes cannot appeal to any
normal, scientific, experience. In his bare metaphysical solitude,
how can he deny that events might just happen? And if he thinks
the contrary, shouldn't he then worry whether the Demon might
be working on him, making him think this although it is not true?

    However, it gets worse when we arrive at the next step. Consider
my idea of someone who is perfectly punctual. Does this need a
perfectly punctual cause? Surely a better thing to think would be
this. I can simply define what it is for someone to be perfectly
punctual. It means that they are never late (or perhaps, never early
and never late). To understand what it would be for someone to be
like that, I do not have to have come across such a person. I can describe them in advance. I understand what condition they have to
satisfy without any such acquaintance, and indeed even if nobody
is ever like that.
    Probably Descartes would reject the analogy. Perhaps he thinks
of it more like this. Do I have an idea of a perfect mathematician?
Well, I can start by thinking of a mathematician as one who never
makes mistakes. But that is hardly adequate. A perfect mathematician would be imaginative and inventive as well. Now, with my very
limited knowledge of mathematics, I only have a very confused understanding of what that would be like. In general, I cannot clearly
comprehend or understand inventions before they come alongotherwise, I would be making the inventions myself! So perhaps it
would take a perfect mathematician to give me a good idea (a `clear
and distinct' idea) of what a perfect mathematician would be like.

    Well, perhaps; but now it becomes doubtful whether I do have a
clear and distinct idea of a perfect mathematician, and analogously, of a perfect being. Generally, what happens if I frame this
idea is that I think more as I did when thinking of someone perfectly punctual. I think of an agent who never makes mistakes,
never behaves unkindly, never finds things he cannot do, and so
on. I might add in imagination something like a kind of glow, but
it is clear that this will not help. It surely seems presumptuous, or
even blasphemous, to allow myself a complete, clear, comprehension of God's attributes.
    In fact, elsewhere in his writings Descartes gives a rather lovely
analogy, but one which threatens to