Salaam Aleikum, Before giving his logical proof, in the proposition 6 he makes very remarkable statement, where he make sure that we are talking about the group/set of all possible beings/causes. This means that we don't care if there were an infinity or finite causes in past, or there is an infinity amount of multi universes or finite, he comes to logical conclusion that it always needs an necessary being to cause the group to exist. 1. Something exists. 2. Whatever exists is eit