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

they exclude heaven from this kind of potency, because according to them
it is heaven which provides this directing power for all existents?
However, the argument of the ancients he relates here has only
dialectical value, partly because much in it which is in reality a conclusion
of a proof is assumed to be self-evident and partly because things are
opposed in it which are not really in opposition. It is also dialectical
because its premisses are probable and common notions. This was
Avicenna’s method of proving that the heavenly body was an animated
body, but for this the ancients have a more efficient and clearer proof.
Ghazali says:
I say:
The objection is that we can assume besides your theory
three hypotheses which cannot be proved to be untrue. The
first is that we assume the movement of heaven to take
place through constraint by another body which desires its
movement and makes it turn eternally, and that this body
which sets it in motion is neither a sphere nor a
circumference nor a heaven; their assertion is therefore false
that the movement of heaven is voluntary and that heaven is
animated, and what we have said is possible, and it cannot
be denied except by a presumption of impossibility.
This is false, for the philosophers have proved that outside heaven there
is no other body, and it cannot be inside heaven; besides, were this body
to set it in motion, it would necessarily have to be moved itself, and we
should have an infinite regress.
Ghazali says:
The second hypothesis is to say: ‘The movement occurs
by constraint and its principle is the will of God, and indeed
we say that the downward movement of a body also occurs
by constraint, through God’s creating this movement in this
body; and the same can be said of all the other movements
of those bodies which are not living. ‘
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