May asked:

What is Descartes's argument to show that God is not a deceiver? In Meditation 4 Descartes
describes the role of "understanding" and "will" in human judgements, in an argument to show that
God cannot be blamed for our mistakes. But I'm having trouble understanding the two roles.

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In his 4th Meditation, an analysis of the origin of error, Descartes first considers whether God could
be the cause of errors directly. He rejects this, since God cannot be a deceiver: "For, first of all, I
recognise it to be impossible that He should ever deceive me; for in all fraud and deception some
imperfection is to be found, and although it may appear that the power of deception is a mark of
subtilty or power, yet the desire to deceive without doubt testifies to malice or feebleness, and
accordingly cannot be found in God. [since God is perfect]."

In other words: God might deceive us:

I. to spare truth, or

II.to manipulate us

But if so,

III. why doesn't God being all powerful not simply adjust reality instead of appearance?

IV.this would mean God needed something from us. But being all powerful God wouldn't need
anybody!

So either way, a perfect being can't be a deceiver (and therefore not the source of error).

Later, Descartes offers this argument, involving the faculties of understanding and will:

Fact: God gave me finite understanding and infinite will Suspicion: Error is caused by the discrepancy
between my finite understanding and my infinite will.

The Argument in short:

V. God can't be blamed for giving me finite understanding.

VI.God can't be blamed for giving me infinite will.

VII.But error springs from the fact that "the scope of the will is wider than that of the intellect"
Therefore, again God can't be blamed for error, but it's my fault.

The Argument in detail:

VIII. Our reason cannot be faulted since, first of all, the ideas we do have cannot be considered
formally false. And, secondly, concerning the ideas we do not have, this lack cannot be counted a
positive defect of the intellect (a flaw), but merely a characterisation of its finitude (The fact that my
printer cannot also create the documents that it prints out would not normally be considered a flaw in
the device, merely a limitation of it). I cannot complain of God that He did not give me a greater
faculty of understanding (could the printer complain not being the writer?). Therefore, the intellect has
no inherent defect, but it does have limits.

IX. The faculty of the will itself does not produce error since the will is a perfect faculty (I can will
anything) — indeed, my will is as perfect as God's (God's is only greater in terms of power,
knowledge, and the objects He can affect).

X. As Descartes can find no reason to hold either of these faculties individually responsible for error,
he concludes "Whence then come my errors? They come from the sole fact that since the will is much
wider in its range and compass than the understanding, I do not restrain it within the same bounds,
but extend it also to things which I do not understand: and as the will is of itself indifferent to these, it
easily falls into error and sin, and chooses the evil for the good, or the false for the true."

Taking all this into consideration, error seems actually to be caused by the discrepancy between my
finite understanding and my infinite will. Convincing?

Simone Klein