Tasalsul is the belief that the present moment is preceded by an infinite number of past events. In proving the existence of God, Imam Al-Ghazali offers three arguments for the impossibility of this belief in his Al-Iqtisad Fi Al-I’tiqad:
|All of the Philosophers agree that the bodies of the world are inseparable from events, and yet they claim that the world is beginningless. So if it is said: “you claim that whatever is inseparable from events, is itself emergent. What is your proof for this?” We say: if the world were beginningless, while being inseparable from events, then this would mean that an infinite number of past events occurred, entailing that the number of orbits each celestial body completed be infinite. This is impossible, because whatever entails an impossibility is itself impossible, and we will now show that three impossibilities follow from this belief.
The first if this were true, then it would mean that an endlessness [i.e. the infinite number of past events] was “completed”, “concluded”, or “came to an end”, and the three expressions are synonymous. So it would follow that an endlessness came to an end. And this is clearly contradictory.
The second if the number of orbits completed by each celestial body were not finite, then the number of orbits completed would have been either: even, odd, neither even nor odd, or both even and odd. Each of the four possibilities is impossible in the case of an infinite number of orbits, so the completion of an infinite number of orbits is impossible.
It is impossible for an infinite number of completed orbits to be neither even nor odd, or both even and odd. An even number is one that is divisible by two, like ten for example. Whereas an odd number is one that is not-divisible by two, like nine. And any amount is composed of a multiplicity of singulars, such that this amount is either divisible by two, or not. Therefore, it is impossible for an amount to be neither divisible nor not-divisible by two, and it is impossible for an amount to be both divisible and not-divisible by two.
It is impossible for an infinite number of completed orbits to be even, since an even number is so because it lacks one, such that if this one were added to it, it turns odd. But how can an infinite amount lack anything? It is also impossible for this amount to be odd, because an odd number becomes even by adding one to it, so it can only remain odd as long as it lacks this one. But then again, how can an infinite amount be lacking in anything?
The Third it would also follow that there be two amounts, each infinite, while one is lesser than the other. And it is impossible for an infinite amount to be less than another. This is because the lesser amount lacks the difference that if added to it, would make it equal to the other. But how can an infinite amount lack anything?
To make matters clearer: they [the Philosophers] claim that Saturn completes one orbit [around the Earth] every thirty years, while the Sun completes one orbit every year. So the number of orbits that Saturn completes annually, is a thirtieth of the Sun’s. But if one proposes that Saturn has been orbiting since eternity past, then the number of its orbits would have been infinite, even though this amount is also less than the orbits of the Sun. After all, a thirtieth of an amount is obviously less than the full amount. Similarly, the moon completes twelve orbits every year, which means that the Sun completes twelfth as many orbits as the moon. Each amount is said to be infinite, while each is less than the other, and this is a clear impossibility.
– Al-Ghazali, Al-Iqtisad Fi Al-I’tiqad, page 28
 The Philosophers maintained that the celestial bodies have been orbiting the earth since eternity past. So the Imam argues that if the world were beginningless, then this would mean that the number of orbits each celestial body completed, would have been infinite.