A friend of mine came up with an annoyingly simple argument for a Newtonian, deterministic, causally necessary universe. I can't see how to refute it Based on 2 things- The "Principle Of Least Action" A particular definition of "Event". That's it! "Principle Of Least Action"- The "easiest" "event" always happens first. "Event"- Smallest possible unit of change. (The smallest possible difference between 2 states of affairs) So- You have; S.O.A (state of affairs) "A" @ T1 then- "Event" then S.O.A (state of affairs) "B" @ T2 That's it! If you commit to the "2 things" S.O.A "B" must neccessarily follow S.O.A "A". ie "Causation" could be seen as the "one to one association of (dynamic) states of affairs with the "easiest" events to which they give rise. (nothing metaphysical being postulated here) In principle, therefore (even if you object to the use of the term "Causation"), the ever changing world can be fully described in terms of the cascade of infinitesimal "events", each of which (according to the "Principle Of Least Action") is the first to arise from the S.O.A preceding it. PLEASE refute this!