The third argument:

If each individual event has a beginning, the whole must have a beginning, just as, since every individual among the Zanj is black, all of them must be black.

I say:

This is the argument of Abū al-Husayn al-Basrī and others like him among the Mu'tazilah.

The fourth argument:

Past events have come to an end with us. If past events were without end, something infinite would be finite, which is impossible.

and others like him among the Mu'tazilah.

The fourth argument:

Past events have come to an end with us. If past events were without end, something infinite would be finite, which is impossible.

This is of the same kind as the second argument.

The fifth argument:

Either an event occurred in the beginningless past, or none did. The former is impossible, because that event would have been preceded by nonexistence, whereas the beginningless past cannot be preceded by nonexistence. If no event existed in the beginningless past, then we have identified a state in which no event existed. Thus, each event is preceded by nonexistence.

The sixth argument:

Past things have come into existence. Whatever has come into existence has been bounded by existence, and whatever is bounded by existence is finite. Therefore, past events must be finite in number.