If a cause includes all the prerequisites upon which the...

If a cause includes all the prerequisites upon which the existence of the effect depends, so that the effect cannot fail to exist when it is there, it is a complete cause. If a cause includes only some of those prerequisites it is an incomplete cause. The two differ in the respect that the existence of a complete cause necessitates the existence of the effect, and its non-existence the non-existence of the effect.

But the existence of an incomplete cause does not necessitate the effect’s existence, though its non-existence does necessitate the effect’s non-existence. Similarly, causes are classified into ‘single’ (wâhid) and ‘multiple’ (katsîr) and into ‘simple’ (basîth) and ‘composite’ (murakkab). A simple cause is one that has no parts, and a composite cause is its contrary.

A simple cause is either simple in respect of external reality such as the immaterial Intellect and the accidents, or it is simple from the viewpoint of the Intellect, i.e. neither composed of matter and form in external reality nor of genus and differentia in the intellect. The simplest of entities is that which is not composed of existence and quiddity, and that is the Necessary Being, exalted is His Name.

Causes are also classified into ‘proximate’ and ‘remote.’ A proximate cause is one in which there is no intermediary term between it and its effect. A remote cause, such as the cause of a cause, is its contrary. Causes are also classified into ‘internal’ and ‘external.’ The internal causes (al-‘ilal al-dâkhiliyyah, also called ‘ilal al-qiwâm, i.e., the constituting causes) are matter and form, whereby the effect is constituted and sustained.

The external causes (al- ‘ilal al-khârijiyyah, also called ‘ilal al-wujûd, the causes of existence) are the ‘agent’ (al-fail, i.e. efficient cause) and the ‘end’ (al-ghâyah, i.e. the final caust) The agent is sometimes called ‘mâ bihi al-wujûd (that on which the effect’s existence depends) and the end is called ‘mâ li ajalihi wujûd (the raison d’etre). Cause are also classified into ‘real’ (al-‘ilal al-haqîqiyyah) and ‘preparatory’ causes (al-mu’iddât).

There is a kind of figurative usage involved in naming the preparatory factors as ’causes,’ for they not real causes.