26 ideas
| 18487 | We want to know what makes sentences true, rather than defining 'true' [McFetridge] |
| Full Idea: The generalisation 'What makes a (any) sentence true?' is not a request for definitions of 'true' (the concept), but rather requests for (partial) explanations of why certain particular sentences are true. | |
| From: Ian McFetridge (Truth, Correspondence, Explanation and Knowledge [1977], II) | |
| A reaction: McFetridge is responding to the shortcomings of Tarski's account of truth. The mystery seems to be why some of our representations of the world are 'successful', and others are not. |
| 12463 | Unlike correspondence, truthmaking can be one truth to many truthmakers, or vice versa [Jacobs] |
| Full Idea: I assume a form of truthmaking theory, ..which is a many-many relation, unlike, say correspondence, so that one entity can make multiple truths true and one truth can have multiple truthmakers. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §1) | |
| A reaction: This sounds like common sense, once you think about it. One tree makes many things true, and one statement about trees is made true by many trees. |
| 18488 | We normally explain natural events by citing further facts [McFetridge] |
| Full Idea: If one were asked 'What makes salt soluble in water?', the most natural answer would be something of the style 'The fact that it has such-and-such structure'. | |
| From: Ian McFetridge (Truth, Correspondence, Explanation and Knowledge [1977], II) | |
| A reaction: Personally I would want to talk about its 'powers' (dispositional properties), rather than its 'structure' (categorical properties). This defends facts, but you could easily paraphrase 'fact' out of this reply (as McFetridge realised). |
| 14375 | If structures result from intrinsic natures of properties, the 'relations' between them can drop out [Jacobs] |
| Full Idea: If a relation holds between two properties as a result of their intrinsic natures, then it appears the relation between the properties is not needed to do the structuring of reality; the properties themselves suffice to fix the structure. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §4.1) | |
| A reaction: [the first bit quotes Jubien 2007] He cites a group of scientific essentialists as spokesmen for this view. Sounds right to me. No on seems able to pin down what a relation is - which may be because there is no such entity. |
| 14378 | Science aims at identifying the structure and nature of the powers that exist [Jacobs] |
| Full Idea: Scientific practice seems aimed precisely at identifying the structure and nature of the powers that exist. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §4.3) | |
| A reaction: Good. Friends of powers should look at this nice paper by Jacobs. There is a good degree of support for this view from pronouncements of modern scientists. If scientists don't support it, they should. Otherwise they are trapped in the superficial. |
| 12467 | Powers come from concrete particulars, not from the laws of nature [Jacobs] |
| Full Idea: The source of powers is not the laws of nature; it is the powerful nature of the ordinary properties of concrete particulars. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §4.2) | |
| A reaction: This pithily summarises my own view. People who think the powers of the world derive from the laws either have an implicit religious framework, or they are giving no thought at all to the ontological status of the laws. |
| 12184 | Logical necessity overrules all other necessities [McFetridge] |
| Full Idea: If it is logically necessary that if p then q, then there is no other sense of 'necessary' in which it is not necessary that if p then q. | |
| From: Ian McFetridge (Logical Necessity: Some Issues [1986], §1) | |
| A reaction: The thesis which McFetridge proposes to defend. The obvious rival would be metaphysical necessity, and the rival claim would presumably be that things are only logically necessary if that is entailed by a metaphysical necessity. Metaphysics drives logic. |
| 15083 | The fundamental case of logical necessity is the valid conclusion of an inference [McFetridge, by Hale] |
| Full Idea: McFetridge's conception of logical necessity is one which sees the concept as receiving its fundamental exemplification in the connection between the premiss and conclusion of a deductively valid inference. | |
| From: report of Ian McFetridge (Logical Necessity: Some Issues [1986]) by Bob Hale - Absolute Necessities 2 | |
| A reaction: This would mean that p could be logically necessary but false (if it was a valid argument from false premisses). What if it was a valid inference in a dodgy logical system (including 'tonk', for example)? |
| 15084 | In the McFetridge view, logical necessity means a consequent must be true if the antecedent is [McFetridge, by Hale] |
| Full Idea: McFetridge's view proves that if the conditional corresponding to a valid inference is logically necessary, then there is no sense in which it is possible that its antecedent be true but its consequent false. ..This result generalises to any statement. | |
| From: report of Ian McFetridge (Logical Necessity: Some Issues [1986]) by Bob Hale - Absolute Necessities 2 | |
| A reaction: I am becoming puzzled by Hale's assertion that logical necessity is 'absolute', while resting his case on a conditional. Are we interested in the necessity of the inference, or the necessity of the consequent? |
| 12180 | Logical necessity requires that a valid argument be necessary [McFetridge] |
| Full Idea: There will be a legitimate notion of 'logical' necessity only if there is a notion of necessity which attaches to the claim, concerning a deductively valid argument, that if the premisses are true then so is the conclusion. | |
| From: Ian McFetridge (Logical Necessity: Some Issues [1986], §1) | |
| A reaction: He quotes Aristotle's Idea 11148 in support. Is this resting a stronger idea on a weaker one? Or is it the wrong way round? We endorse validity because we see the necessity; we don't endorse necessity because we see 'validity'. |
| 12181 | Traditionally, logical necessity is the strongest, and entails any other necessities [McFetridge] |
| Full Idea: The traditional crucial assumption is that logical necessity is the strongest notion of necessity. If it is logically necessary that p, then it is necessary that p in any other use of the notion of necessity there may be (physically, practically etc.). | |
| From: Ian McFetridge (Logical Necessity: Some Issues [1986], §1) | |
| A reaction: Sounds right. We might say it is physically necessary simply because it is logically necessary, and even that it is metaphysically necessary because it is logically necessary (required by logic). Logical possibility is hence the weakest kind? |
| 12183 | It is only logical necessity if there is absolutely no sense in which it could be false [McFetridge] |
| Full Idea: Is there any sense in which, despite an ascription of necessity to p, it is held that not-p is possible? If there is, then the original claim then it was necessary is not a claim of 'logical' necessity (which is the strongest necessity). | |
| From: Ian McFetridge (Logical Necessity: Some Issues [1986], §1) | |
| A reaction: See Idea 12181, which leads up to this proposed "test" for logical necessity. McFetridge has already put epistemic ('for all I know') possibility to one side. □p→¬◊¬p is the standard reading of necessity. His word 'sense' bears the burden. |
| 12192 | The mark of logical necessity is deduction from any suppositions whatever [McFetridge] |
| Full Idea: The manifestation of the belief that a mode of inference is logically necessarily truth-preserving is the preparedness to employ that mode of inference in reasoning from any set of suppositions whatsoever. | |
| From: Ian McFetridge (Logical Necessity: Some Issues [1986], §4) | |
| A reaction: He rests this on the idea of 'cotenability' of the two sides of a counterfactual (in Mill, Goodman and Lewis). There seems, at first blush, to be a problem of the relevance of the presuppositions. |
| 14377 | Possibilities are manifestations of some power, and impossibilies rest on no powers [Jacobs] |
| Full Idea: To be possible is just to be one of the many manifestations of some power, and to be impossible is to be a manifestation of no power. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §4.2.1) | |
| A reaction: [This remark occurs in a discussion of theistic Aristotelianism] I like this. If we say that something is possible, the correct question is to ask what power could bring it about. |
| 14376 | 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. |
| 12182 | We assert epistemic possibility without commitment to logical possibility [McFetridge] |
| Full Idea: Time- and person-relative epistemic possibility can be asserted even when logical possibility cannot, such as undecided mathematical propositions. 'It may be that p' just comes to 'For all I know, not-p'. | |
| From: Ian McFetridge (Logical Necessity: Some Issues [1986], §1) | |
| A reaction: If it is possible 'for all I know', then it could be actual for all I know, and if we accept that it might be actual, we could hardly deny that it is logically possible. Logical and epistemic possibilities of mathematical p stand or fall together. |
| 14379 | 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? |
| 12187 | Objectual modal realists believe in possible worlds; non-objectual ones rest it on the actual world [McFetridge] |
| Full Idea: The 'objectual modal realist' holds that what makes modal beliefs true are certain modal objects, typically 'possible worlds'. ..The 'non-objectual modal realist' says modal judgements are made true by how things stand with respect to this world. | |
| From: Ian McFetridge (Logical Necessity: Some Issues [1986], §2) | |
| A reaction: I am an enthusiastic 'non-objectual modal realist'. I accept the argument that real possible worlds have no relevance to the actual world, and explain nothing (see Jubien). The possibilities reside in the 'powers' of this world. See Molnar on powers. |
| 14372 | Possible worlds are just not suitable truthmakers for modality [Jacobs] |
| Full Idea: Possible worlds are just not the sorts of things that could ground modality; they are not suitable truthmakers. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §3) | |
| A reaction: Are possible world theorists actually claiming that the worlds 'ground' modality? Maybe Lewis is, since all those concrete worlds had better do some hard work, but for the ersatzist they just provide a kind of formal semantics, leaving ontology to others. |
| 12186 | Modal realists hold that necessities and possibilities are part of the totality of facts [McFetridge] |
| Full Idea: The 'modal realist' holds that part of the totality of what is the case, the totality of facts, are such things as that certain events could have happened, certain propositions are necessarily true, if this happened then that would have been the case. | |
| From: Ian McFetridge (Logical Necessity: Some Issues [1986], §2) | |
| A reaction: I am an enthusiastic modal realist. If the aim of philosophy is 'to understand' (and I take that to be the master idea of the subject) then no understanding is possible which excludes the possibilities and necessities in things. |
| 12466 | All modality is in the properties and relations of the actual world [Jacobs] |
| Full Idea: Properties and the relations between them introduce modal connections in the actual world. ..This is a strong form of actualism, since all of modality is part of the fundamental fabric of the actual world. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §4) | |
| A reaction: This is the view of modality which I find most congenial, with the notion of 'powers' giving us the conceptual framework on which to build an account. |
| 14371 | We can base counterfactuals on powers, not possible worlds, and hence define necessity [Jacobs] |
| Full Idea: Together with a definition of possibility and necessity in terms of counterfactuals, the powers semantics of counterfactuals generates a semantics for modality that appeals to causal powers and not possible worlds. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §1) | |
| A reaction: Wonderful. Just what the doctor ordered. The only caveat is that if we say that reality is built up from fundamental powers, then might those powers change their character without losing their identity (e.g. gravity getting weaker)? |
| 12465 | Concrete worlds, unlike fictions, at least offer evidence of how the actual world could be [Jacobs] |
| Full Idea: Lewis's concrete worlds give a better account of modality (than fictional worlds). When I learn that a man like me drives a truck, I gain evidence for the fact that I can drive a truck. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §3) | |
| A reaction: Cf. Idea 12464. Jacobs still rightly rejects this as an account of possibility, since the possibility that I might drive a truck must be rooted in me, not in some other person who drives a truck, even if that person is very like me. |
| 12464 | If some book described a possibe life for you, that isn't what makes such a life possible [Jacobs] |
| Full Idea: Suppose somewhere deep in the rain forest is a book that includes a story about you as a truck-driver. I doubt that you would be inclined the think that that story, that book, is the reason you could have been a truck driver. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §3) | |
| A reaction: This begins to look like a totally overwhelming and obvious reason why possible worlds (especially as stories) don't give a good metaphysical account of possibility. They provide a semantic structure for modal reasoning, but that is entirely different. |
| 12469 | Possible worlds semantics gives little insight into modality [Jacobs] |
| Full Idea: If we want our semantics for modality to give us insight into the truthmakers for modality, then possible worlds semantics is inadequate. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §4.4) | |
| A reaction: [See the other ideas of Jacobs (and Jubien) for this] It is an interesting question whether a semantics for a logic is meant to give us insight into how things really are, or whether it just builds nice models. Satisfaction, or truth? |
| 1513 | The Egyptians were the first to say the soul is immortal and reincarnated [Herodotus] |
| Full Idea: The Egyptians were the first to claim that the soul of a human being is immortal, and that each time the body dies the soul enters another creature just as it is being born. | |
| From: Herodotus (The Histories [c.435 BCE], 2.123.2) |