Here are a few of the main ideas I have taken from Saul Kripke.
- Essential properties are the same in all worlds. So c cannot be an essential property if light has a rest frame, because c cannot be 1 in its own rest frame. But c can be , aka , in every reference frame including its own. Here is a link to Stanford on Essential v. accidental properties.
- Names fix the referent: They just “pick out” or “point to” the object being discussed. They do not define the object, and especially they do not define the object on a bundle of qualities whose composition might change contingently. For example, “Peter Freed is a 5’11” man with curly black hair” is contingent and goes wrong as I age. Would “Peter Freed” cease to have meaning? But if it just picks out the referent, me, Kripke thinks we’re all set. Its a spatiotemporal understanding of names. It points at them! (Pointing is a spatiotemporal act).
- Kripke has a real grudge against people who think you look at possible worlds through a telescope, as he puts it a few times. He thinks their objects are right here, at hand. You point to an object here and talk about it in its possible world. This is very Barcan of him, in which the thing in the possible world exists already in this world. e.g. . Do you see how the initial is not through a telescope, but near at hand, it is the object right here?
1. Naming and Necessity (1970)
A sustained argument against Frege and Russell. “Frege and Russell certainly seem to have the full blown theory according to which a proper name is not a rigid designator and is synonymous with the description which replaced it.” (N&N p.58). He thinks to name something is to point at it and then track it through all possible worlds.
- Spatiotemporal inaccessibility of possible worlds “Generally speaking, another possible world is too far away. Even if we travel faster than light, we won’t get to it.”
- Rigid Designation: “Let’s call something a rigid designator if in every possible world it designates the same object
- Essential properties are necessary: When we think of a property as essential to an object we usually mean that it is true of that object in any case where it would have existed.
- One of the intuitive theses I will maintain in these talks is that names are rigid designators.
- Those who have argued that to make sense of the notion of rigid designator, we must antecedently make sense of ‘criteria of transworld identity’ have precisely reversed the cart and the horse; it is because we can refer (rigidly) to Nixon, and stipulate that we are speaking of what might have happened to him (under certain circumstances), that ‘transworld identifications’ are unproblematic in such cases
- If someone identifies necessity with a prioricity, and thinks that objects are named by means of uniquely identifying properties, he may think that it is the properties used to identify the object which, being known about it a priori, must be used to identify it in all possible worlds, to find out which object is Nixon. As against this, I repeat: (r) Generally, things aren’t ‘found out’ about a counterfactual situation, they are stipulated; (2) possible worlds need not be given purely qualitatively, as if we were looking at them through a telescope. And we will see shortly that the properties an object has in every counterfactual world have nothing to do with properties used to identify it in the actual world.
- Similarly, given certain counterfactual vicissitudes in the history of the molecules of a table, T, one may ask whether T would exist, in that situation, or whether a certain bunch of molecules, which in that situation would constitute a table, constitute the very same table T. In each case, we seek criteria of identity across possible worlds for certain particulars in terms of those for other, more ‘basic’, particulars.
- [Bold is mine. I consider this a crucial section for my own work.] If a quality is an abstract object, a bundle of qualities is an object of an even higher degree of abstraction, not a particular. Philosophers have come to the opposite view through a false dilemma: they have asked, are these objects behind the bundle of qualities, or is the object nothing but the bundle? Neither is the case; this table is wooden, brown, in the room, etc. It has all these properties and is not a thing without properties, behind them; but it should not therefore be identified with the set, or ‘bundle’ , of its properties, nor with the subset of its essential properties. Don’t ask: how can I identify this table in another possible world, except by its properties? I have the table in my hands, I can point to it. and when I ask whether it might have been in another room, I am talking, by definition, about it. I don’t have to identify it after seeing it through a telescope. If I am talking about it, I am talking about it, in the same way as when I say that our hands might have been painted green, I have stipulated that I am talking about greenness. Some properties of an object may be essential to it, in that it could not have failed to have them. But these properties are not used to identify the object in another possible world, for such an identification is not needed. Nor need the essential properties of an object be the properties used to identify it in the actual world, if indeed it is identified in the actual world by means of properties (I have up to now left the question open). (pp52-53)
- Most important, even when we can replace questions about an object by questions about its parts, we need not do so. We can refer to the object and ask what might have happened to it. So, we do not begin with worlds (which are supposed somehow to be real, and whose qualities, but not whose objects, are perceptible to us), and then ask about criteria of transworld identification; on the contrary, we begin with the objects, which we have, and can identify, in the actual world. We can then ask whether certain things might have been true of the objects. (p53)
- Wittgenstein says something very puzzling about this. He says: ‘There is one thing of which one can say neither that it is one meter long nor that it is not one meter long, and that is the standard meter in Paris. But this is, of course, not to ascribe any extraordinary property to it, but only to mark its peculiar role in the language game of measuring with a meter rule.’ (54)
- Contingent a priori truths: “What then, is the epistemological status of the statement ‘Stick S is one meter long at to’, for someone who has fixed the metric system by reference to stick S? It would seem that he knows it a priori. For if he used stick S to fix the reference of the term ‘one meter’, then as a result of this kind of ‘definition’ (which is not an abbreviative or synonymous definition), he knows automatically, without further investigation, that S is one meter 10ng.21 On the other hand, even if S is used as the standard of a meter, the metaphysical status of ‘S is one meter long’ will be that of a contingent statement, provided that ‘one meter’ is regarded as a rigid designator: under appropriate stresses and strains, heatings or coolings, S would have had a length other than one meter even at to. (Such statements as ‘Water boils at 100°C at sea level’ can have a similar status.) So in this sense, there are contingent a priori truths.” (N&N p.56)
- Fixing the Referent: “Suppose we say, ‘Aristotle is the greatest man who studied with Plato’. If we used that as a definition, the name ‘Aristotle’ is to mean ‘the greatest man who studied with Plato’. Then of course in some other possible world that man might not have studied with Plato and some other man would have been Aristotle. If, on the other hand, we merely use the description to fix the reformt then that man will be the referent of ‘Aristotle’ in all possible worlds. The only use of the description will have been to pick out to which man we mean to refer. But then, when we say counterfactually ‘suppose Aristotle had never gone into philosophy at all’, we need not mean ‘suppose a man who studied with Plato, and taught Alexander the Great, and wrote this and that, and so on, had never gone into philosophy at all’, which might seem like a contradiction. We need only mean, ‘suppose that that man had never gone into philosophy at all’.” (N&N p. 57)
- Proto-relativity (he uses a comet rather than a Lorentz transformation to get a coordinate change signifying nothing): “When the mythical agent first saw Hesperus, he may well have fixed his reference by saying, ‘I shall use “Hesperus” as a name of the heavenly body appearing in yonder position in the sky.’ He then fixed the reference of ‘Hesperus’ by its apparent celestial position. Does it follow that it is part of the meaning of the name that Hesperus has such and such position at the time in question? Surely not: if Hesperus had been hit earlier by a comet, it might have been visible at a different position at that time. In such a counterfactual situation we would say that Hesperus would not have occupied that position, but not that Hesperus would not have been Hesperus. The reason is that ‘Hesperus’ rigidly designates a certain heavenly body and ‘the body in yonder position’ does not-a different body, or no body might have been in that position, but no other body might have been Hesperus (though another body, not Hesperus, might have been called ‘Hesperus’). Indeed, as I have said, I will hold that names are always rigid designators.”(N&N 57-8)
- “The case of fixing the reference of ‘one meter’ is a very clear example in which someone, just because he fixed the reference in this way, can in some sense know a priori that the length of this stick is a meter without regarding it as a necessary truth. Maybe the thesis about a prioricity implying necessity can be modified. It does appear to state some insight which might be important, and true, about epistemology. In a way an example like this may seem like a trivial counterexample which is not really the point of what some people think when they think that only necessary truths can be known a priori. Well, if the thesis that all a priori truth is necessary is to be immune from this sort of counterexample, it needs to be modified in some way. Unmodified it leads to confusion about the nature of reference. And I myself have no idea how it should be modified or restated, or if such a modification or restatement is possible. (fn: If someone fixes a meter as ‘the length of stick S at to’, then in some sense he knows a priori that the length of stick S at to is one meter, even though he uses this statement to express a contingent truth. But, merely by fixing a system of measurement, has he thereby learned some (contingent) information about the world, some new fact that he did not know before? It seems plausible that in some sense he did not, even though it is undeniably a contingent fact that S is one meter long. So there may be a case for reformulating the thesis that everything a priori is necessary so as to save it from this type of counterexample. As I said, I don’t know how such a reformulation would go; the reformulation should not be such as to make the thesis trivial (e.g., by defining a priori as known to be necessary (instead of true) independently of experience) ; and the converse thesis would still be false.” (N&N 63)
- If one was determining the referent of a name like ‘Glunk’ to himself and made the following decision, ‘I shall use the term “Glunk” to refer to the man that I call “Glunk” ” this would get one nowhere. One had better have some independent determination of the referent of ‘Glunk’. This is a good example of a blatantly circular determination. (N&N 73)
- It just is not, in any intuitive sense of necessity, a necessary truth that Aristotle had the properties commonly attributed to him. (N&N 75)
- Hitler might have spent all his days in quiet in Linz. In that case we would not say that then this man would not have been Hitler, for we use the name ‘Hitler’ just as the name of that man, even in describing other possible worlds. (This is the notion which I called a rigid designator in the previous talk.) Suppose we do decide to pick out the reference of ‘Hitler’, as the man who succeeded in having more Jews killed than anyone else managed to do in history. That is the way we pick out the reference of the name; but in another counterfactual situation where some one else would have gained this discredit, we wouldn’t say that in that case that other man would have been Hitler. If Hitler had never come to power, Hitler would not have had the property which I am supposing we use to fix the reference of his name. (N&N 75)
- If I have determined that Hesperus is the thing that I saw in the evening over there, then I will know, just from making that determination of the referent, that if there is any Hesperus at all it’s the thing I saw in the evening. (N&N 78)
Other Related work:
Lewis, David On the Plurality of Worlds
Lecture notes on Naming and Necessity