1. All causes and effects are perceived as appearances an experienced.
2. What is cause and effect is always an event.
3. In an event, a State-A [cause] changes to new and different State-B.
4. Appearance and Perception of State-B is always preceded by Perception of State-A.
5. As such there is an inherent order of from State-A to State-B in any event.
- Kant illustrated the default order in the case of a ship moving downstream.
The perception of the ship downstream [State-B] is followed from the perception of the ship upstream [State-A]. It is IMPOSSIBLE that the ship is perceive in this case, as first downstream [State-B] then upstream [State-A].
7. This necessary order is the inherent a priori Law of Causality, i.e. that state for any effect there must be a cause.
8. So Kant approach is that whatever event that is to be perceived and experienced must be grounded upon the Law of Causality a priori in contrast to Hume basis that Law of Causality cannot be determined from experiences [a posteriori] and psychology.
9. Having countered Hume's challenge, Kant has to prove where does the Law of Causality emerge a priori from.
10. Kant proved the Concept and Law of Causality as Category or Pure Concept of the Understanding via the Transcendental Deduction.
...................
Therefore Kant had soundly proved the necessity of the Law of Causality not directly from experience but rather from an a priori basis.
There are objectors to Kant's Transcendental Deduction, but that is because they [as Transcendental Realists] have not fully understood [not necessary agree with] Kant's philosophy on this matter and on its whole context.
Basically the problem with the objections can be further explained down the contention between realism and anti-realism.
All Issues of Philosophy are Reducible to Realism vs Idealism
viewtopic.php?f=5&t=28643
Views?