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How did Diodorus Cronus and Philo of Megara disagree about when a conditional statement is true?

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Ancient logic Zeno's paradox, illustrated by Achilles' racing a tortoise.

Diodorus Cronus and Philo of Megara held differing views on the truth conditions of conditional propositions, specifically regarding whether a conditional's truth value can change over time.12

Diodorus Cronus argued that a conditional "If p, then q" is true if and only if it is, and has always been, impossible for the antecedent p to be true while the consequent q is false. Because this definition relies on the impossibility of such a state occurring at any point in time (past, present, or future), a conditional that is true for Diodorus remains true permanently; it cannot change its truth value.12
Philo of Megara proposed a less restrictive interpretation, defining a conditional as true if and only if it does not currently have a true antecedent and a false consequent. This definition corresponds to the modern concept of material implication. Unlike Diodorus’s view, Philo’s interpretation allows for the possibility that a conditional may change its truth value over time as the truth values of its constituent propositions change.12