display all the ideas for this combination of philosophers
5 ideas
5734 | Possible worlds make it possible to define necessity and counterfactuals without new primitives [Melia] |
Full Idea: In modal logic the concepts of necessity and counterfactuals are not interdefinable, so the language needs two primitives to represent them, but with the machinery of possible worlds they are defined by what is the case in all worlds, or close worlds. | |
From: Joseph Melia (Modality [2003], Ch.1) | |
A reaction: If your motivation is to reduce ontology to the barest of minimums (which it was for David Lewis) then it is paradoxical that the existence of possible worlds may be the way to achieve it. I doubt, though, whether a commitment to their reality is needed. |
5742 | In possible worlds semantics the modal operators are treated as quantifiers [Melia] |
Full Idea: The central idea in possible worlds semantics is that the modal operators are treated as quantifiers. | |
From: Joseph Melia (Modality [2003], Ch.2) | |
A reaction: It seems an essential requirement of metaphysics that an account be given of possibility and necessity, and it is also a good dream to keep the ontology simple. Commitment to possible worlds is the bizarre outcome of this dream. |
5743 | If possible worlds semantics is not realist about possible worlds, logic becomes merely formal [Melia] |
Full Idea: It has proved difficult to justify possible worlds semantics without accepting possible worlds. Without a secure metaphysical underpinning, the results in logic are in danger of having nothing more than a formal significance. | |
From: Joseph Melia (Modality [2003], Ch.2) | |
A reaction: This makes nicely clear why Lewis's controversial modal realism has to be taken seriously. It appears that the key problem is truth, because that is needed to define validity, but you can't have truth without some sort of metaphysics. |
5749 | Possible worlds could be real as mathematics, propositions, properties, or like books [Melia] |
Full Idea: One can be a realist about possible worlds without adopting Lewis's extreme views; they might be abstract or mathematical entities; they might be sets of propositions or maximal uninstantiated properties; they might be like books or pictures. | |
From: Joseph Melia (Modality [2003], Ch.6) | |
A reaction: My intuition is that once you go down the road of realism about possible worlds, Lewis's full concrete realism looks at least as attractive as any of these options. You can discuss the 'average man' in an economic theory without realism. |
5751 | The truth of propositions at possible worlds are implied by the world, just as in books [Melia] |
Full Idea: Propositions are true at possible worlds in much the same way as they are true at books: by being implied by the book. | |
From: Joseph Melia (Modality [2003], Ch.7) | |
A reaction: An intriguing way to introduce the view that possible worlds should be seen as like books. The truth-makers of propositions about the actual world are items in it, but the truth-makers in novels (say) are the conditions of the whole work as united. |