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

application of the term ‘necessary existence’, for we call this
entity ‘reality’ or ‘quiddity’ and this reality exists, i. e. it is not
non-existent and is not denied, but its existence is brought
into a relation with it, and if you like to call this ‘consequent’
and ‘necessary attribute’, we shall not quibble about words, if
you have once acknowledged that it has no agent for its
existence and that this existence has not ceased to be
eternal and to have no efficient cause; if, however, you
understand by ‘consequent’ and ‘effect’ that it has an
efficient cause, this is not true. But if you mean something
else, this is conceded, for it is not impossible, z since the
demonstration proves only the end of a causal series and its
ending in an existent reality; a positive quiddity, therefore, is
possible, and there is no need to deny the quiddity.
If it is said: Then the quiddity becomes a cause for the
existence which is consequent on it, and the existence
becomes an effect and an object of the act, we answer: The
quiddity in temporal things is not a cause of their existence,
and why should it therefore be the case in the eternal, if you
mean by ‘cause’ the agent? But if you mean something else
by it, namely that without which it could not be, let that be
accepted, for there is nothing impossible in it; the
impossibility lies only in the infinite causal series, and if this
series only comes to a final term, then the impossibility is
cancelled; impossibility can be understood only on this point,
therefore you must give a proof of its impossibility.
All the proofs of the philosophers are nothing but
presumptions that the term has a sense from which certain
consequences follow, and nothing but the supposition that
demonstration has in fact proved a necessary existent with
the meaning the philosophers ascribed to it. We have,
however, shown previously that this is not true. In short, this
proof of the philosophers comes down to the proof of the
denial of attributes and of the division into genus and specific
difference; only this proof is still more ambiguous and weak,
for this plurality is purely verbal, for the intellect does allow
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