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

This argument is sophistical because possibility is a universal which
has individuals outside the mind like all the other universals, and
knowledge is not knowledge of the universal concept, but it is a knowledge
of individuals in a universal way which the mind attains in the case of the
individuals, when it abstracts from them one common nature which is
distributed among the different matters. The nature, therefore, of the
universal is not identical with the nature of the things of which it is a
universal. Ghazali is here in error, for he assumes that the nature of
possibility is the nature of the universal, without there being individuals on
which this universal, i.e. the universal concept of possibility, depends. The
universal, however, is not the object of knowledge; on the contrary through
it the things become known, although it exists potentially in the nature of
the things known;’ otherwise its apprehension of the individuals, in so far
as they are universals, would be false. This apprehension would indeed
be false if the nature of the object known were essentially individual, not
accidentally individual, whereas the opposite is the case: it is accidentally
individual, essentially universal. Therefore if the mind did not apprehend
the individuals in so far as they are universal, it would be in error and
make false judgements about them. But if it abstracts those natures which
subsist in the individual things from their matter, and makes them
universal, then it is possible that it judges them rightly; otherwise it would
confuse those natures, of which the possible is one.
The theory of the philosophers that universals exist only in the mind, not
in the external world, only means that the universals exist actually only in
the mind, and not in the external world, not that they do not exist at all in
the external world, for the meaning is that they exist potentially, not
actually in the external world; indeed, if they did not exist at all in the
outside world they would be false. Since universals exist outside the mind
in potency and possibilities exist outside the soul in potency, the nature of
universals in regard
to this resembles that of possibilities. And for this reason Ghazali tried
to deceive people by a sophism, for he compared possibility to the
universals because of their both being potentially in reality, and then he
assumed that the philosophers assert that universals do not exist at all
outside the soul; from which he deduced that possibility does not exist
outside the soul. What an ugly and crude sophism!
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