Saul KripkeSaul Kripke is a philosopher and logician and emeritus professor at Princeton. He attacked the theory that proper names are descriptions, for examples bundles of properties, as espoused by Gottlob Frege and especially Bertrand Russell. The Frege-Russell theory of descriptions was also a theory of meaning. The meaning of a proper name was said to consist in all the properties attached to the named person. The Frege-Russell theory was also a theory of reference, of denotation, of terms that "pick out" or identify an individual, whether a human being, an inanimate object, or a natural kind. Frege and Russell said that some of these properties can be substituted in statements for the name and preserve the truth value of the statement. For example, George Washington can be replaced by "the first president of the United States." But descriptive properties can be problematic. Kripke's modal analysis of alternative possibilities shows that the first president of the United States might not have been Washington. Things might have been otherwise. Washington might have died in the Revolutionary War. But his proper name, given as a child by his parents, told to family and friends and then to people widely through a chain of communications that grew worldwide, could only be a reference to this unique individual, a reference that identifies him more strongly than any accidental property. Kripke says that proper names are "rigid designators" that only refer to the objects they designate. They contain none of the likely accidental properties that accrue to persons during their lifetimes, such as "first president." Rigidity of proper names refers to their unchanging, even necessary character, says Kriple, colorfully described as "true in all possible worlds," as today's modal philosophers like to say, even "necessary a posteriori," which is only "true" within a logical system, not a fact in the irreducibly contingent material world. Kripke says that once an object is "baptized" with the first use (the origin) of its name, it more reliably denotes that individual than any of the properties the individual might acquire during a lifetime that might evolve in multiple possible ways. But note that the rigidity of a proper name is only relative to its early date. Any property that was established in the past is now unchangeable – "necessary ex post facto?" – even if it could have been otherwise, so it too might serve as a rigid designator.
Reference and IdentityUsing the ancient example of "Hesperus is Phosphorus," the two ancient names for the planet Venus that appears as both the Evening star and the Morning star, Kripke claims that since the two names refer to the same thing, they are identical. But this seems extreme. Granted that someone who knows that Venus can appear on either side of the sun, Hesperus and Phosphorus refer to the same thing. But there is no way the names themselves (as words) are identical to one another. We must select a subset of the information contained in the two words and in factual, even scientific and empirical knowledge available, to pick out the fact that these words refer to the same object. There are not two things (names) here that are identical to one another. Identical terms should be substitutable for one another in propositions and preserve the truth value. Hesperus and Phosphorus are two different words. They contain significantly different information. One name describes a morning phenomenon. So, there is no truth to the statement "Phosphorus is the Evening Star." Phosphorus never appears in the evening. Circumlocutions are needed like "What we call Phosphorus is a planet that sometimes appears as Hesperus." Part of the information content here is that we have two words referring to one thing. But each word provides different knowledge about the planet Venus, one telling that Venus sometimes appears to the East of the Sun, the other that it sometimes appears to the West. It is false that "The Morning Star IS The Evening Star." except in a limited sense. Most all statements of identity between two things should be paraphrased as "these two things are identical in some respect." They are only the same if we ignore their differences. For example, Hesperus and Phosphorus are identical qua referents to the planet Venus Gottfried Leibniz's famous law about the "identity of indiscernibles" can not be an absolute statement. The only absolute identity is self-identity. All things are identical only to themselves. Two indiscernibles are only indiscernible qua – in some respects. They are easily discerned to be two objects, in different places for example. But any two things are similar if we ignore all their differences, just as they are different if we ignore their similarities. Exceptions are the identical and "indistinguishable" elementary particles of quantum physics, a deep problem for quantum mechanics and for metaphysics. Hesperus and Phosphorus are identical only qua referents to a planet, and there is nothing necessary about this fact except that it began in the past and is now a convention and tradition, and as such Hesperus and Phosphorus are Kripke rigid designators. But we cannot forget the obvious fact from linguistic theory, whether Peirce semiotics or Saussure semiology, that the names Hesperus and Phosphorus are arbitrary symbols, with no information in common with the planet Venus. In ancient semitic languages, the planet was Ishtar for centuries before the Latin name for the love goddess. Given the fact that all human language terms are contingent and historically accidental, we must struggle to understand Kripke's claim for the names' necessity.
Necessary A Posteriori?Kripke has defined a different kind of necessity from that usually identified with the analytic and the a priori. He alters the traditional distinction between the necessary and the contingent. Kripke calls his idea metaphysical necessity to distinguish it from epistemic necessity. Kripke further distinguishes analyticity and a prioricity from necessity. For him, analyticity is a semantic notion, a priori is epistemic, and his necessity is a metaphysical notion. Analyticity covers everything known to be true or false by definition of the terms involved. This includes logical and mathematical truths, such as "A is A," and "7 + 5 = 12." He says, "an analytic statement is, in some sense, true by virtue of its meaning and true in all possible worlds by virtue of its meaning. Then something which is analytically true will be both necessary and a priori. (That's sort of stipulative.)" (Naming and Necessity, p.39). Metaphysical necessity concerns facts that are known to be the case by the nature of a physical object. This is based on the physical presumption that the way the world is, for example the laws of nature, could not have been otherwise. It may also be based on the fact that any event in the past is now fixed and so can be called metaphysically necessary? In any case, Kripke believes that we discover the essential properties, the essence, of physical objects empirically (p.110). Anything that has been empirically determined to be the case thus can be called metaphysically necessary or "necessary a posteriori," says Kripke. Consider the modal claim 'Necessarily, water is H2O.' It is said to follow from the empirical and a posteriori claim 'Water is H2O' together with an a priori claim, such as 'If water is H2O, then necessarily, water is H2O' (p.128). But this seems dangerously like the redundancy in 'If water is H2O, then it is true that water is H2O'? Kripke's other examples include: it is necessary that gold is necessarily a metal, that it is yellow, and has atomic number 79 (p.118); lightning is necessarily an electrical discharge (p.132); "This table (pointing at a table in the room) is necessarily made of wood," if it was made of wood. Indeed, he says that the table was by metaphysical necessity made of the exact wood that it was made of. We can take Kripke's "metaphysical necessity" with a metaphorical grain of salt (necessarily NaCl). This is because the physical world contains the possibility that the carpenter could have chosen a different piece of wood, or the table could have been made of ice (Kripke's cryptic alternative, p.114).
Possible WorldsKripke and David Lewis are both famous for using the concept of possible worlds, but there are some extreme and very important differences between them. Kripke thinks that Lewis's idea has "encouraged philosophical pseudo-problems and misleading pictures." One major difference is that Lewis thinks of his super-infinity of possible worlds as actually existing in an infinite space-time continuum, where Kripke thinks his possible worlds are merely ways of talking about the alternative possibilities in our actual world. He says that ''possible worlds' are total 'ways the world might have been', or states or histories of the entire world, or 'counterfactual situations' might even be better.
I will say something briefly about 'possible worlds'. (I hope to elaborate elsewhere.) In the present monograph I argued against those misuses of the concept that regard possible worlds as something like distant planets, like our own surroundings but somehow existing in a different dimension, or that lead to spurious problems of 'transworld identification'. Further, if one wishes to avoid the Weltangst and philosophical confusions that many philosophers have associated with the 'worlds' terminology, I recommended that 'possible state (or history) of the world', or 'counterfactual situation' might be better. One should even remind oneself that the 'worlds' terminology can often be replaced by modal talk—'It is possible that . . .' 'Possible worlds' are little more than the miniworlds of school probability blown large. It is true that there are problems in the general notion not involved in the miniature version. The miniature worlds are tightly controlled, both as to the objects involved (two dice), the relevant properties (number on face shown), and (thus) the relevant idea of possibility. 'Possible worlds' are total 'ways the world might have been', or states or histories of the entire world. To think of the totality of all of them involves much more idealization, and more mind-boggling questions, than the less ambitious elementary school analogue. Certainly the philosopher of 'possible worlds' must take care that his technical apparatus not push him to ask questions whose meaningfulness is not supported by our original intuitions of possibility that gave the apparatus its point. Further, in practice we cannot describe a complete counterfactual course of events and have no need to do so.When thinking about different possibilities in the actual world, e.g., what if Nixon had lost the 1968 presidential election and Humphrey won it, Nixon in Kripke's alternative possible world is the same individual, differing only in the property of losing the election. All of Kripke's possible worlds are different ways our actual world might have been. By contrast, A practical description of the extent to which the 'counterfactual situation' differs in the relevant way from the actual facts is sufficient; the 'counterfactual situation' could be thought of as a miniworld or a ministate, restricted to features of the world relevant to the problem at hand... There is nothing wrong in principle with taking these [possible worlds], for philosophical or for technical purposes, as (abstract) entities—the innocence of the grammar school analogue should allay any anxieties on that score. (Indeed the general notion of 'sample space' that forms the basis of modern probability theory is just that of such a space of possible worlds.) However, we should avoid the pitfalls that seem much more tempting to philosophers with their grand worlds than to schoolchildren with their modest versions. There are no special grounds to suppose that possible worlds must be given qualitatively, or that there need be any genuine problem of 'transworld identification'—the fact that larger and more complex states are involved than in the case of the dice makes no difference to this point. The 'actual world'—better, the actual state, or history of the world —should not be confused with the enormous scattered object that surrounds us. The latter might also have been called 'the (actual) world', but it is not the relevant object here. Thus the possible but not actual worlds are not phantom duplicates of the 'world' in this other sense. Perhaps such confusions would have been less likely but for the terminological accident that 'possible worlds' rather than 'possible states', or 'histories', of the world, or 'counterfactual situations' had been used. Certainly they would have been avoided had philosophers adhered to the common practices of schoolchildren and probabilists. David Lewis describes a Nixon in an alternate world as not the same individual, but a "counterpart" of Nixon who has the same bundle of properties as the actual Nixon, with the exception of the election loss. This raises the troubling problem of a "trans-world individual." Clearly no matter how similar, individuals in two different worlds are not identical.
I wish at this point to introduce something which I need in the methodology of discussing the theory of names that I'm talking about. We need the notion of 'identity across possible worlds' as it's usually and, as I think, somewhat misleadingly called. (Misleadingly, because the phrase suggests that there is a special problem of 'transworld identification", that we cannot trivially stipulate whom or what we are talking about when we imagine another possible world. The term 'possible world' may also mislead; perhaps it suggests the 'foreign country' picture. I have sometimes used 'counterfactual situation' in the text; Michael Slote has suggested that 'possible state (or history) of the world' might be less misleading than 'possible world'. It is better still, to avoid confusion, not to say, 'In some possible world, Humphrey would have won' but rather, simply, 'Humphrey might have won'. The apparatus of possible words has (I hope) been very useful as far as the set-theoretic model-theory of quantified modal logic is concerned, but has encouraged philosophical pseudo-problems and misleading pictures.) One of the intuitive theses I will maintain in these talks is that names are rigid designators. Certainly they seem to satisfy the intuitive test mentioned above: although someone other than the U.S. President in 1970 might have been the U.S. President in 1970 (e.g., Humphrey might have), no one other than Nixon might have been Nixon. In the same way, a designator rigidly designates a certain object if it designates that object wherever the object exists; if, in addition, the object is a necessary existent, the designator can be called strongly rigid. For example, 'the President of the U.S. in 1970' designates a certain man, Nixon; but someone else (e.g., Humphrey) might have been the President in 1970, and Nixon might not have; so this designator is not rigid. In these lectures, I will argue, intuitively, that proper names are rigid designators, for although the man (Nixon) might not have been the President, it is not the case that he might not have been Nixon (though he might not have been called 'Nixon'). 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. (Of course I don't imply that language contains a name for every object Demonstratives can be used as rigid designators, and free variables can be used as rigid designators of unspecified objects. Of course when we specify a counterfactual situation, we do not describe the whole possible world, but only the portion which interests us.)It is critical to note that metaphysicians proposing possible worlds are for the most part materialists and determinists who do not believe in the existence of ontological possibilities in our world. First, they "index" our world as the "actual world." They are actualists who say that the only possibilities have always been whatever actually happened. This is Dan Dennett's position, for example, not that far from the original actualist, Diodorus Cronus. Moreover, all of their infinite number of possible worlds are governed by deterministic laws of nature. This means that there are also no real possibilities in any of their possible worlds, only actualities there as well. Now this is quite ironic, since the invention of possible worlds was proposed as a superior way of talking about counterfactual possibilities in our world. Since information philosophy defends the existence of alternative possibilities leading to different futures, we can adopt a form of modal discourse to describe these possibilities as possible future worlds for our to-be-actualized world. It turns out there is an infinity of such possible future worlds. The infinity is not as large as the absurdly extravagant number in David Lewis's possible worlds, which have counterparts for each and every living person with every imaginable difference in each of our counterparts, each counterpart in its own unique world. Thus there are Lewisian worlds in which your counterpart is a butcher, baker, candlestick maker, and every other known occupation. There are possible worlds in which your counterpart eats every possible breakfast food, drives every possible car, and lives in every block on every street in every city or town in the entire word. This extravagance is of course part of Lewis's appeal. It makes Hugh Everett's "many worlds" of quantum mechanics (which split the universe in two when a physicist makes a quantum measurement) minuscule, indeed quite parsimonious, by comparison. Specifically, when an Everett universe splits into two, it doubles the matter and energy in the new universe(s) – an extreme violation of the principle of the conservation of matter/energy – and it also doubles the information. Apart from that absurdity, the two universes differ by only one bit of information, for example, whether the electron spin measured up or down in the quantum measurement. Similarly, for every Lewisian universe, the change of one bit of information implies one other possible universe in which all the infinite number of other bits stay exactly the same. But Lewis imagines that every single bit in the universe may be changed at any time, an order of physical infinities that rivals the greatest number that Georg Cantor ever imagined. Is David Lewis ontologically committed to such a number?
Free WillAlthough Kripke does not seem to have said anything about the problem of free will, his view of "possible worlds" may be sympathetic to human freedom, since he describes the worlds as "ways the world might have been." In our two-stage model of free will, we can describe the alternative possibilities for action generated by an agent in the first stage as "possible worlds." They are "counterfactual situations" in Kripke's sense, involving a single individual. Suppose the agent is considering five different courses of action. During the second stage of evaluation and deliberation only one of the five options (each a "possible world") will become actualized. The agent is the same individual of interest in these five possible worlds. There are no Lewisian "counterparts." There is no problem of "transworld identification." Note that these five possible worlds are extremely close to one another, "nearby" in the sense of their total information content. We can focus on the "miniworld" of the five options and hold the rest of the universe constant. As Kripke described it, "the 'counterfactual situation' could be thought of as a miniworld or a ministate, restricted to features of the world relevant to the problem at hand." Quantification over the information in each world shows that the difference between them is very small number of bits, especially when compared to the typical examples given in possible worlds cases. In the case of Humphrey winning the election, millions of persons would have to have done something different. Such worlds are hardly "nearby" one another For typical cases of a free decision, the possible worlds require only small differences in the mind of a single person. Kripke argued against the identity of mind and body (or brain), and in this example it would only be the thoughts of the agent that pick out the possible world that will be actualized. Our thoughts are free. Our actions are willed by an adequately determined evaluation and decision process, not one that was pre-determined by the mechanical laws of nature acting on our material bodies.
Separating Necessity from Analyticity and A PrioricityKripke is well known for his "metaphysical necessity" and the "necessary a posteriori." Broadly speaking, modern philosophy has been a search for truth, for a priori, analytic, certain, necessary, and provable truth. For many philosophers, a priori, analytic, and necessary, have been more or less synonymous. But all these concepts are mere ideas, invented by humans, some aspects of which have been discovered to be independent of the minds that invented them, notably formal logic and mathematics. Logic and mathematics are systems of thought, inside which the concept of demonstrable (apodeictic) truth is useful, but with limits set by Kurt Gödel's incompleteness theorem. The truths of logic and mathematics appear to exist "outside of space and time." We call them a priori because their proofs are independent of experience, although they were abstracted empirically from concrete human experiences. Analyticity is the idea that some statements, some propositions in the form of sentences, can be true by the definitions or meanings of the words in the sentences. This is correct, though limited by verbal difficulties such as Russell's paradox and numerous other puzzles and paradoxes. Analytic language philosophers claim to connect our words with objects, material things, and thereby tell us something about the world. Some modal logicians, inspired by Kripke, claim that words that are names of things are necessary a posteriori, "true in all possible worlds." But this is nonsense, because we invented all those words and worlds. They are mere ideas. Perhaps the deepest of all these philosophical ideas is necessity. Information philosophy can now tell us that there is no such thing as absolute necessity. There is of course an adequate determinism in the macroscopic world that explains the appearance of deterministic laws of nature, of cause and effect, for example. This is because macroscopic objects consist of vast numbers of atoms and their individual random quantum events average out. But there is no metaphysical necessity. At the fundamental microscopic level of material reality, there is an irreducible contingency and indeterminacy. Everything that we know, everything we can say, is fundamentally empirical, based on factual evidence, the analysis of experiences that have been recorded in human minds. So information philosophy is not what we can logically know about the world, nor what we can analytically say about the world, nor what is necessarily the case in the world. There is nothing that is the case that is necessary and perfectly determined by logic, by language, or by the physical laws of nature. Our world and its future are open and contingent, with possibilities that are the source of human freedom. For the most part, philosophers and scientists do not believe in possibilities, despite their invented "possible worlds," which are on inspection merely multiple "actual worlds." This is because they cannot accept the idea of ontological chance. They hope to show that the appearance of chance is the result of human ignorance, that chance is merely an epistemic phenomenon. Now chance, like truth, is just another idea, just some more information. But what an idea! In a self-referential virtuous circle, it turns out that without the real possibilities that result from ontological chance, there can be no new information. Information philosophy offers cosmological and biological evidence for the creation of new information in the universe. So it follows that chance is real, fortunately something that we can keep under control. We are biological beings that have evolved, thanks to chance, from primitive single-cell communicating information structures to multi-cellular organisms whose defining aspect is the creation and communication of information. The theory of communication of information is the foundation of our "information age." To understand how we know things is to understand how knowledge represents the material world of embodied "information structures" in the mental world of immaterial ideas. All knowledge starts with the recording of experiences. The experiences of thinking, perceiving, knowing, feeling, desiring, deciding, and acting may be bracketed by philosophers as "mental" phenomena, but they are no less real than other "physical" phenomena. They are themselves physical phenomena.
They are just not material things. Information philosophy defines human knowledge as immaterial information in a mind, or embodied in an external artifact that is an information structure (e.g., a book), part of the sum of all human knowledge. Information in the mind about something in the external world is a proper subset of the information in the external object. It is isomorphic to a small part of the total information in or about the object. The information in living things, artifacts, and especially machines, consists of much more than the material components and their arrangement (positions over time). It also consists of all the information processing (e.g., messaging) that goes on inside the thing as it realizes its entelechy or telos, its internal or external purpose. All science begins with information gathered from experimental observations, which are mental phenomena. Observations are experiences recorded in minds. So all knowledge of the physical world rests on the mental. All scientific knowledge is information shared among the minds of a community of inquirers. As such science is a collection of thoughts in thinkers, immaterial and mental, some might say fundamental. Recall Descartes' argument that the experience of thinking is that which for him is the most certain.
ReferencesKripke, S. 1971, "Identity and Necessity," in Identity and Individuation, Milton Munitz, NY University Press
Kripke, Saul. 1981. Naming and Necessity. Blackwell Publishing.