the universal “human being” is the existence of its individual instances. There is no need to posit an existence for the universal in external reality distinct from that of its individual instances; rather, their very existence is its existence.
It is evident that, if the existence of the universal in external reality means the existence of its individual instances, no rational person disputes this, although they may dispute whether the universal taken absolutely, without any condition—the natural universal—exists in external reality. Accordingly, what they mean by the existence of motion as a universal in external reality is the existence of its successive instances, one after another. Every instance is preceded by something else, but this successive genus, some of whose instances exist one after another, is not itself preceded by anything else.
Alternatively, you may say: We do not concede that the universal does not exist in external reality; we concede only that it does not exist there as a universal. This is the natural universal, taken absolutely, without any condition, such as what is denoted by “human being” without any condition. It exists in external reality, but as a particular, individual being. Its instances exist either together or successively, as future occurrences succeed one another. The existence of particular motions is thus like the existence of all other particular things, and the existence of what is denoted by “motion” is like the existence of all other things denoted by universal terms. What is judged to be beginningless is the kind, which exists only successively, not all at once.
If someone says, “What is denoted by ‘motion’ does not exist in external reality with its instances together, as individual human beings do,” he has spoken truthfully. But if he says, “It does not exist successively,” this is not conceded. Whoever says this must consequently hold that no motion exists in external reality at all, whether finite or infinite. This contradicts sensory perception and reason.
Ibn Sīnā recognized this point and discussed the existence of motion