Therefore in order to disprove the second assumption...

Therefore in order to disprove the second assumption additional arguments must be utilised one of which, is that it is impossible for all of the existents to be possible existents. As this argument is not self-evident, it will be explained as follows: Every possible existent needs a cause and it is impossible to have an endless chain of causes. Thus the endless chain of causes is compelled to terminate at an existent, which is not in need of a cause, i.e. the necessary existent.

This argument has introduced other philosophical concepts, which require a brief explanation of it and things related to it. a. Cause and effect If an existent requires another existent and depends upon that other existent for its being, then in philosophical terminology the caused existent is known as the effect and the other existent is known as the cause. However it is possible that a cause can also be an effect, and be a dependable existent, not absolutely free from need.

If a cause is absolutely free from need and does not depend upon any other existent then it will be the Absolute cause. By now we have become familiar with the definition of the terms cause and effect. We will now provide an explanation of the premise mentioned (every possible existent needs a cause). Possible existence does not exist in-itself and has no alternative other than to depend upon another existent.

Thus every predicate, which is recognised for the subject is established either by itself (bi-l-dhāt) or by means of other than itself (bi-l-ghayr). For example every thing either shines in and of itself or requires something else for its illumination, or every body is oily in itself or needs oil for becoming oily. It is impossible for something in itself to not be illuminating or oily and not receive light or oil from something else, and at the same time be oily and illuminating!

Hence the establishment of existence for a subject is either through its essence or by means of other than itself, and when it is not through its essence then it has to be by means of other than itself. Therefore every possible existent, which is not realised through its essence, is bound to be realised by means of other than itself, which implies that it is an effect. This provides us with the fundamental principle of the intellect, that every possible existent needs a cause.

However, some have conceived that the principle of causation means that all existents need a cause and therefore God needs a primary cause.