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

passage between being and non-being. Nor is there movement, since a
thing that moves is neither here nor there, since it moves-what we call
movement is being at rest at different space-atoms at different time-atoms.
It is the denial of potentiality, possibility in rerum natura, that Ghazali uses
to refute the Aristotelian idea of an eternal matter in which the
potentialities are found of everything that can or will happen. For,
according to Aristotle, matter must be eternal and cannot have become,
since it is, itself, the condition for all becoming.
It maybe mentioned here that the modern static theory of movement is
akin to the Megarian-Ash‘arite doctrine of the denial of movement and
becoming. Bertrand Russell, for instance, although he does not accept the
Megarian atomic conception, but holds with Aristotle that movement and
rest take place in time, not in the instant, defines movement as being at
different places at different times. At the same time, although he rejects
the Megarian conception of ‘jumps’, he affirms that the moving body
always passes from one position to another by gradual transition. But
‘passing’ implies, just as much as ‘jumping’, something more than mere
being, namely, the movement which both theories deny and the identity of
the moving body.
On the idea of possibility another argument for the eternity of the world is
based. It is affirmed that if the world had been created an infinite number
of possibilities of its creation, that is, an eternal duration of its possibility,
would have preceded it. But nothing possible can be eternal, since
everything possible must be realized. The idea that everything possible
has to be realized is found in Aristotle himself, who says that if there could
be an eternal possible that were not realized, it would be impossible, not
possible, since the impossible is that which will never be realized. Aristotle
does not see that this definition is contrary to the basic idea of his own
philosophy-the reality of a possibility which may or may not become realand
that by declaring that the possible will have to happen he reduces it to
a necessity, and by admitting that everything that happens had to happen
he denies that the possibility of its not happening could precede it, i.e. he
accepts, in fact, the Megarian conception of possibility which he himself
had tried to refute. Averroës, who agrees with his master on this point, is
not aware either of the implication of the definition. On the other hand, the
Ash‘arites, notwithstanding their denial of potentiality, maintain that for
18