Aquinas' Second Way

'Now in efficient causes it is not possible to go on to infinity, because in all efficient causes following in order, the first is the cause of the intermediate cause, and the intermediate is the cause of the ultimate cause, whether the intermediate cause be several or only one. Now to take away the cause is to take away the effect. %%Therefore, if there be no first cause among efficient causes, there will be no ultimate, nor any intermediate cause.%% ' {Aquinas)

Aquinas' second way deals with the concept of %%cause and effect.%% Everything observable in nature is subject to this law, according to Aquinas, although the idea that this chain of cause and effect could be traced back infinitely is seen as impossible by him. This then leads to he question: 'What was the first cause?' and for Aquinas, the answer is 'God.'

Aquinas states here, not only the idea that cause and effect is a simple, undeniable law of the universe but also that %%it is impossible for anything within the universe to cause itself%%. (It would be like you being your own parents -you cannot exist before you exist -you need something to bring you into existence.)

If you imagine a line of dominos, the first (efficient cause) is the one that causes the second (intermediate cause) one to fall, which in turn causes the third (ultimate cause) one to fall. However, the third one would not have fallen, had the first one not have hit the second one. Aquinas' idea of efficient cause followed by intermediate cause and ending at ultimate cause can seem confusing at first, but, by using the %%domino analogy%% it gives a suitable visual expression of the philosophical idea.

Summary

1. Everything which exists has been caused to come to existence.
2. Nothing can be the cause of it’s own existence.
3. Everything which has come to exist has been caused to exist by something other than itself.
4. Impossible for a chain of causes to go on to infinity.