Tahafut_al-Tahafut-transl-Engl-van-den-Bergh

And his adversaries insist on these two very points: ( 1 ) that the act of the
agent necessarily implies a change and that each change has a principle
which causes it; (2) that the Eternal cannot change in any way. But all this
is difficult to prove.
The Ash’arites are forced to assume either a first agent or a first act of
this agent, for they cannot admit that the disposition of the agent, relative
to the effect, when he acts is the same as his disposition, when he does
not act. This implies therefore a new disposition or a new relation, and this
necessarily either in the agent, or in the effect, or in both? But in this case,
if we posit as a principle that for each new disposition there is an agent,
this new disposition in the first agent will either need another agent, and
then this first agent was not the first and was not on his own account
sufficient for the act but needed another, or the agent of the disposition
which is the condition of the agent’s act will be identical with the agent of
the act. Then this act which we regarded as being the first act arising out
of him will not be the first, but his act producing the disposition which is the
condition of the effect will be anterior to the act producing the effect. This,
you see, is a necessary consequence, unless one allows that new
dispositions may arise in the agents without a cause. But this is absurd,
unless one believes that there are things which happen at haphazard and
by themselves, a theory of the old philosophers who denied the agent,; the
falsehood of which is self-evident.
In Ghazali’s objection there is a confusion. For our expressions ‘eternal
will’ and ‘temporal will’ are equivocal, indeed contrary. For the empirical
will is a faculty which possesses the possibility of doing equally one of two
contraries and then of receiving equally one of the two contraries willed.
For the will is the desire of the agent towards action. When the agent acts,
the desire ceases and the thing willed happens, and this desire and this
act are equally related to both the contraries. But when one says: ‘There is
a Wilier who wills eternally one of two contraries in Himself’, the definition
of the will is abandoned, for we have transferred its nature from the
possible to the necessary. If it is objected that in an eternal will the will
does not cease through the presence of the object willed, for as an eternal
will has no beginning there is no moment in it which is specially
determined for the realization of the object willed, we answer: this is not
obvious, unless we say that demonstrative proof leads to the existence of
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