Combining Texts

Ideas for 'Thinking About Mathematics', 'Philosophical Logic' and 'A Powers Theory of Modality'

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4 ideas

10. Modality / B. Possibility / 1. Possibility
States of affairs are only possible if some substance could initiate a causal chain to get there [Jacobs]
     Full Idea: A non-actual state of affairs in possible if there actually was a substance capable of initiating a causal chain, perhaps non-deterministic, that could lead to the state of affairs that we claim is possible.
     From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §4.2)
     A reaction: [He is quoting A.R. Pruss 2002] That seems exactly right. Of course the initial substance(s) might create a further substance, such as a transuranic element, which then produces the state of affairs. I favour this strongly actualist view.
10. Modality / B. Possibility / 8. Conditionals / a. Conditionals
Three conditionals theories: Materialism (material conditional), Idealism (true=assertable), Nihilism (no truth) [Burgess]
     Full Idea: Three main theories of the truth of indicative conditionals are Materialism (the conditions are the same as for the material conditional), Idealism (identifying assertability with truth-value), and Nihilism (no truth, just assertability).
     From: John P. Burgess (Philosophical Logic [2009], 4.3)
It is doubtful whether the negation of a conditional has any clear meaning [Burgess]
     Full Idea: It is contentious whether conditionals have negations, and whether 'it is not the case that if A,B' has any clear meaning.
     From: John P. Burgess (Philosophical Logic [2009], 4.9)
     A reaction: This seems to be connected to Lewis's proof that a probability conditional cannot be reduced to a single proposition. If a conditional only applies to A-worlds, it is not surprising that its meaning gets lost when it leaves that world.
10. Modality / B. Possibility / 9. Counterfactuals
Counterfactuals invite us to consider the powers picked out by the antecedent [Jacobs]
     Full Idea: A counterfactual is an invitation to consider what the properties picked out by the antecedent are powers for (where Lewis 1973 took it to be an invitation to consider what goes on in a selected possible world).
     From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §4.4.3)
     A reaction: A beautifully simple proposal from Jacobs, with which I agree. This seems to be an expansion of the Ramsey test for conditionals, where you consider the antecedent being true, and see what follows. What, we ask Ramsey, would make it follow?