Pauen I 273
Determinism/Peter van Inwagen/Pauen: determinism is not an implication of physicalism. The principle of causal closure refers to the fact that only physical explanations may be used.
This does not mean that the cause/effect ratio must always be deterministic.
The principle of physical determination does not make a statement about the necessity of certain causal chains but only requires that there is a physically describable change for every change that can be described in a higher level.
van Inwagen: determinism thus stands for the thesis that the state of the world can be derived anytime later from a complete description and knowledge of the state of affair.
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Initial conditions.
Pauen: it is more than controversial that the determinism applies to our physical reality.
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Lewis V 296
Determinism/VsSoft determinism/VsCompatibilism/van InwagenVsLewis: (against the soft determinism which I pretend to represent):
E.g. supposed to reductio that I could have lifted my hand, though determinism would be true.
Then follows from four premises which I cannot deny that I could have produced a false conjunction HL from a proposition H over a time before my birth and a certain proposition about a law L.
Premise 5: if so, then I could have falsified L.
Premise 6: but I could not have falsified L (contradiction).
LewisVsInwagen: 5 and 6 are not both true. Which one is true depends on what Inwagen means by "could have falsified". But not in the ordinary language but in Inwagen's artificial language. Even there it does not matter what Inwagen himself means!
What is important is whether we can give a sense to this at all, which makes all premisses valid without circularity.
Inwagen: (verbally) third meaning for "could have falsified": namely, and only if the acting person could have arranged things the way that his/her acting plus the whole truth about the prehistory together imply the nontruth of the proposition.
Then, premise 6 says that I could not have arranged things the way that I was predestined not to arrange them like that.
Lewis: but it is not at all instructive to see that soft determinism has to reject premise 6 that was interpreted in that way.
V 297
Falsification/action/free will/Lewis: provisional definition: an event falsifies a proposition only if it is necessary that in the case that the event happens, then the proposition is false.
But my act of throwing a rock would not itself falsify the proposition that the window in the course remains intact. Everything that is true, is that my act invokes another event that would falsify the proposition.
The act itself does not falsify any law. It would falsify only a conjunction of prehistory and law.
Everything that is true, is that my act precedes another act - the miracle - and this falsifies the law.
Weak: let us state that I would be able to falsify a proposition in the weak sense if and only if I do something, the proposition would be falsified (but not necessarily by my act and not necessarily by any event evoked by my act). (Lewis pro "weak thesis" (soft determinism)).
Strong: if the proposition is falsified either by my act itself or by an event which has been evoked by my act.
Inwagen/Lewis: the first part of his thesis stands, no matter whether we represent the strong or weak thesis:
If I could lift my hand although determinism is true and I have not lifted it then it is true in the weak and strong sense that I could have falsified the conjunction HL (propositions on the prehistory and the natural laws).
But I could have falsified the proposition L in the weak sense although I could not have falsified it in the strong sense.
Lewis: if we represent the weak sense, I deny premise 6.
If we represent the strong sense, I deny premise 5.
Inwagen: represents both premises by considering analogous cases.
LewisVsInwagen: I believe that the cases are not analogous: they are cases in which the strong case and the weak case do not diverge at all:
Premise 6/Inwagen: he asks us to reject the idea that a physicist could accelerate a particle faster than the light.
LewisVsInwagen: but that does not help to support premise 6 in the weak sense,...
V 298
...because the rejected presumption is that the physicist could falsify a natural law in the strong sense.
Premise 5/Inwagen: here we are to reject the assumption that a traveler might falsify a conjunction of propositions about the prehistory and one about his/her future journey differently than by falsifying the nonhistorical part.
LewisVsInwagen: you can reject the assumption completely which does nothing to support premise 5 in the strong sense. What would follow if one could falsify the conjunction in the strong sense? That one could falsify the non-historical part in the strong sense? This is what premise 5 would support in the strong sense.
Or would only follow (what I think) that the non-historical part could be rejected in the weak sense? The example of the traveler does not help here because a proposition about future journeys could be falsified in the weak as well as the strong sense!
Cf. >
Strength of theories.
