Change

In plain terms

Change requires two things that pull against each other: something must be different, and it must be the same thing that is different. Drop the first and nothing happened; drop the second and one thing was replaced by another.

Parmenides argued that this cannot be coherent. For something to change, what it becomes must not yet be - and what is not, is nothing, so nothing can come from it. Therefore change is illusory.

That is not a sophism to be waved away; it took Aristotle a whole apparatus to answer. His solution is that what changes was already there potentially, so becoming is not from nothing but from a capacity - which dissolves the argument at the cost of introducing potentiality, and most of Western metaphysics follows from that move.

As a philosopher would put it

Aristotle's analysis has three principles - a substratum, a privation and a form - so that change is not something coming from nothing but a persisting subject acquiring a form it previously lacked in potentiality.

Modern metaphysics reframes it as the problem of temporal intrinsics. How can one thing have incompatible properties, bent and straight, without contradiction? Endurantists hold that objects are wholly present at each time and have properties relative to times. Perdurantists hold that objects are extended in time and have temporal parts, so the bent part and the straight part are different parts of one four-dimensional whole - which dissolves the contradiction and makes ordinary objects far stranger.

The Buddhist analysis takes the other extreme: momentariness, on which nothing persists at all and apparent continuity is a rapid succession of distinct events. Nyāya defends persisting substances against it, and the Chinese tradition's Yijing takes change as the fundamental fact requiring no reconciliation with permanence.

What is actually disputed

Whether anything persists through change.

Endurantists hold that ordinary objects are wholly present at each moment and that time-indexing properties handles the contradiction. Perdurantists hold that objects have temporal parts, which handles it more cleanly and implies that what we call a person is a four-dimensional extent of which only a slice is ever present.

Both are consistent, and the choice is made on theoretical cost rather than on evidence.

The Buddhist momentariness doctrine takes the more radical route: nothing persists, and the appearance of an enduring thing is a rapid succession of distinct events, as a flame appears continuous. Nyāya's objection is that momentariness cannot explain recognition, memory or the ordinary fact that one picks up the same cup one put down - and the exchange between them is the sharpest treatment of the question anywhere.