14 ideas
| 16985 | Possible worlds allowed the application of set-theoretic models to modal logic [Kripke] |
| Full Idea: The main and the original motivation for the 'possible worlds analysis' - and the way it clarified modal logic - was that it enabled modal logic to be treated by the same set theoretic techniques of model theory used successfully in extensional logic. | |
| From: Saul A. Kripke (Naming and Necessity preface [1980], p.19 n18) | |
| A reaction: So they should be ascribed the same value that we attribute to classical model theory, whatever that is. |
| 16982 | A man has two names if the historical chains are different - even if they are the same! [Kripke] |
| Full Idea: Two totally distinct 'historical chains' that be sheer accident assign the same name to the same man should probably count as creating distinct names despite the identity of the referents. | |
| From: Saul A. Kripke (Naming and Necessity preface [1980], p.08 n9) | |
| A reaction: A nice puzzle for his own theory. 'What's you name?' 'Alice, and Alice!' |
| 16981 | With the necessity of self-identity plus Leibniz's Law, identity has to be an 'internal' relation [Kripke] |
| Full Idea: It is clear from (x)□(x=x) and Leibniz's Law that identity is an 'internal' relation: (x)(y)(x=y ⊃ □x=y). What pairs (w,y) could be counterexamples? Not pairs of distinct objects, …nor an object and itself. | |
| From: Saul A. Kripke (Naming and Necessity preface [1980], p.03) | |
| A reaction: I take 'internal' to mean that the necessity of identity is intrinsic to the item(s), and not imposed by some other force. |
| 4942 | The indiscernibility of identicals is as self-evident as the law of contradiction [Kripke] |
| Full Idea: It seems to me that the Leibnizian principle of the indiscernibility of identicals (not to be confused with the identity of indiscernibles) is as self-evident as the law of contradiction. | |
| From: Saul A. Kripke (Naming and Necessity preface [1980], p.03) | |
| A reaction: This seems obviously correct, as it says no more than that a thing has whatever properties it has. If a difference is discerned, either you have made a mistake, or it isn't identical. |
| 16984 | I don't think possible worlds reductively reveal the natures of modal operators etc. [Kripke] |
| Full Idea: I do not think of 'possible worlds' as providing a reductive analysis in any philosophically significant sense, that is, as uncovering the ultimate nature, from either an epistemological or a metaphysical view, of modal operators, propositions etc. | |
| From: Saul A. Kripke (Naming and Necessity preface [1980], p.19 n18) | |
| A reaction: I think this remark opens the door for Kit Fine's approach, of showing what modality is by specifying its sources. Possible worlds model the behaviour of modal inferences. |
| 9385 | The very act of designating of an object with properties gives knowledge of a contingent truth [Kripke] |
| Full Idea: If a speaker introduced a designator into a language by a ceremony, then in virtue of his very linguistic act, he would be in a position to say 'I know that Fa', but nevertheless 'Fa' would be a contingent truth (provided F is not an essential property). | |
| From: Saul A. Kripke (Naming and Necessity preface [1980], p.14) | |
| A reaction: If someone else does the designation, I seem to have contingent knowledge that the ceremony has taken place. You needn't experience the object, but you must experience the ceremony, even if you perform it. |
| 4943 | Instead of talking about possible worlds, we can always say "It is possible that.." [Kripke] |
| Full Idea: We should remind ourselves the 'possible worlds' terminology can always be replaced by modal talk, such as "It is possible that…" | |
| From: Saul A. Kripke (Naming and Necessity preface [1980], p.15) | |
| A reaction: Coming from an originator of the possible worlds idea, this is a useful reminder that we don't have to get too excited about the ontological commitments involved. It may be just a 'way to talk', and hence a tool, rather than a truth about reality. |
| 16983 | Probability with dice uses possible worlds, abstractions which fictionally simplify things [Kripke] |
| Full Idea: In studying probabilities with dice, we are introduced at a tender age to a set of 36 (miniature) possible worlds, if we (fictively) ignore everything except the two dice. …The possibilities are abstract states of the dice, not physical entities. | |
| From: Saul A. Kripke (Naming and Necessity preface [1980], p.16) | |
| A reaction: Interesting for the introduction by the great man of the words 'fictional' and 'abstract' into the discussion. He says elsewhere that he takes worlds to be less than real, but more than mere technical devices. |
| 22392 | Morality is inescapable, in descriptive words such as 'dishonest', 'unjust' and 'uncharitable' [Foot] |
| Full Idea: There is a sense in which morality is inescapable - in moral epithets such as 'dishonest', 'unjust', 'uncharitable'; these do not cease to apply to a man because he is indifferent to the ends of morality: they may indeed apply because of his indifference. | |
| From: Philippa Foot (Morality as system of hypothetical imperatives [1972], p.172 n15) | |
| A reaction: Odysseus was admired for lying, and charity wasn't a virtue in the ancient world. They won't go away as factual descriptions, but the values attached to them vary quite a lot. |
| 23685 | Reason is not a motivator of morality [Foot, by Hacker-Wright] |
| Full Idea: In her middle period she changed her mind, and attacks moral rationalism. | |
| From: report of Philippa Foot (Morality as system of hypothetical imperatives [1972]) by John Hacker-Wright - Philippa Foot's Moral Thought Intro | |
| A reaction: That is, she doubted whether moral reasons are sufficient to motivate moral actions, which presumably therefore need desires, as the Humeans claimed. Reasons rely on merely hypothetical rules. |
| 23691 | Rejecting moral rules may be villainous, but it isn't inconsistent [Foot] |
| Full Idea: The man who rejects morality because he sees no reason to obey its rules can be convicted of villainy but not of inconsistency. | |
| From: Philippa Foot (Morality as system of hypothetical imperatives [1972], p.161) | |
| A reaction: This is 'middle period' Foot, when she decided that Hume was right about the need for a desire as moral motivator. Before and after this time, she thought there were reasons to be moral, as well as desires. |
| 16764 | The soul conserves the body, as we see by its dissolution when the soul leaves [Toletus] |
| Full Idea: Every accident of a living thing, as well as all its organs and temperaments and its dispositions are conserved by the soul. We see this from experience, since when that soul recedes, all these dissolve and become corrupted. | |
| From: Franciscus Toletus (Commentary on 'De Anima' [1572], II.1.1), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 24.5 | |
| A reaction: A nice example of observing a phenemonon, but not being able to observe the dependence relation the right way round. Compare Descartes in Idea 16763. |
| 22391 | Saying we 'ought to be moral' makes no sense, unless it relates to some other system [Foot] |
| Full Idea: 'One ought to be moral' makes no sense at all unless the 'ought' has the moral subscript, giving a tautology, or else relates morality to some other system such as prudence or etiquette. | |
| From: Philippa Foot (Morality as system of hypothetical imperatives [1972], p.169 n18) | |
| A reaction: This aims to undercut the Kantian view that morality is an absolute call to duty (filling us with wonder, like the starry heavens). Foot aims to root morality in the real world. |
| 22389 | Morality no more consists of categorical imperatives than etiquette does [Foot] |
| Full Idea: Moral judgements have no better claim to be categorical imperatives than do statements about matters of etiquette. | |
| From: Philippa Foot (Morality as system of hypothetical imperatives [1972], p.164) | |
| A reaction: Her claim is that all moral judgements are responses to situations, and so are hypothetical. This judgement of hers is the culmination of a careful discussion. |