Fine and Williamson on Hyperintensionalism
Brian Leiter at Leiter Reports has just linked to a discussion between Kit Fine and Timothy Williamson and rightly explains that this is philosophy at its best. So you should read it here.
I've written my own summary in case you haven't the time.
What Fine and Williamson are asking is a very basic question about thought, language, and reality. When two statements are true in exactly the same possible circumstances, are they really saying the same thing, or can there still be a deeper difference between them?That is the heart of the dispute. Williamson defends what we can call an intensional framework. Fine thinks that framework is often too coarse, too blunt, and that we need something finer grained, which he calls hyperintensional.
An intensional theory says that if two statements are necessarily equivalent, meaning that they are true in all the same possible cases, then they count as the same in the relevant respect. A hyperintensional theory says that this is not always enough. Two statements can be true in all the same possible worlds and yet still differ in content, structure, explanatory role, or what they are about.A simple example helps. The sentence “P” and the sentence “P or P and Q” are classically equivalent. They always come out true and false together. If P is true, then “P or P and Q” is true. If P is false, then both are false. So an intensionalist says that, at the level that matters, they amount to the same thing. A hyperintensionalist says not so fast. Even though they match across all possible cases, the second sentence has a more complicated structure. It says something in a different way, and that difference may matter for explanation, permission, counterfactuals, and other parts of thought and language.
Fine begins by making a distinction that is absolutely central to his position. He says we must separate intensionalism about reality from intensionalism about language. Intensionalism about reality says that there are no distinctions in reality without a modal difference. “Modal” here means having to do with possibility and necessity. So if two facts always obtain together, necessarily, then they are the same fact. If two properties apply to exactly the same things in every possible world, then they are the same property. On this picture, reality is individuated by modal profile. If there is no difference in where or when something could obtain, then there is no deeper difference there to be found.
Fine calls this a “worldly” conception because it treats possible worlds, or modal variation across worlds, as the measure of real difference. But then he asks a second question. Even if reality were like that, should language also be like that? Must language ignore every difference except necessary equivalence? His answer is no. And this is where his view becomes more subtle than a simple rejection of intensionalism. He says that even if one granted, just for argument’s sake, that reality itself is intensional in Williamson’s sense, it would not follow that our language for describing reality must also be intensional. Language may need to be more discriminating than the reality it describes.
Why? Because the relation between language and reality may be one to many rather than one to one. This is one of Fine’s key ideas. Suppose I say, “It is rainy or windy.” On a one to one picture, that sentence corresponds to one fact, namely the fact that it is rainy or windy. But on a one to many picture, the sentence can be made true in different ways, by different facts: the fact that it is rainy, or the fact that it is windy. So even if the sentence is true in both cases, the route by which it is true differs. Fine thinks that these different truthmaking routes matter. A “truthmaker” is, roughly, whatever in the world makes a statement true. If “grass is green” is true, then grass being green is what makes it true. Truthmaker theory tries to understand meaning and logic partly by asking what sorts of things make sentences true. Fine uses this framework to explain why necessarily equivalent sentences might still differ semantically. Two sentences may line up in truth value across all worlds while differing in the facts that would make them true. That is what gives the hyperintensionalist room to work.
“Johnny is having ice cream” and “Johnny is having ice cream, or Johnny is having ice cream and chocolate” are necessarily equivalent. But the second is true in virtue of a wider range of possible truthmakers. It can be made true by Johnny just having ice cream, or by Johnny having ice cream and chocolate. Fine thinks that difference is real and semantically important. He then gives a practical example involving permission. Suppose someone tells Johnny, “You may have ice cream.” Johnny reasons like this: having ice cream is equivalent to having ice cream or ice cream and chocolate. And if one is allowed “X or Y,” one is allowed X and one is allowed Y. So surely he may have ice cream and chocolate. But ordinary understanding says this reasoning is faulty. The permission was for ice cream, not automatically for all the more complicated descriptions that are classically equivalent to it. Fine thinks hyperintensional distinctions explain why the reasoning breaks down. The expressions are not interchangeable in the relevant context, even though they are necessarily equivalent.
That is a general pattern in his position. He thinks ordinary and formal reasoning often depend on distinctions finer than possible world equivalence can capture.
He then turns to counterfactuals, statements of the form “if this were the case, then that would be the case.” Here his point is more technical, but the basic shape can be explained. He says that in a logic of counterfactuals one might want two things at once. First, one might want to allow embedded counterfactuals, where a counterfactual appears inside another counterfactual, especially on the right hand side. For example, “If P were the case, then if Q were the case, R would be the case.” Second, one might want every such embedded counterfactual to be reducible to a simpler, unembedded form, such as “If P and Q were the case, R would be the case.” Fine claims that under his truthmaker based hyperintensional framework, one can have both expressive richness and simplification into a normal form. A “normal form” is just a standard, cleaned up way of rewriting expressions so that their logical structure becomes easier to see. In elementary logic, for example, one often rewrites formulas into disjunctive normal form. Fine’s idea is that hyperintensional logic can sometimes make this kind of simplification available in areas where intensional logic cannot. Hyperintensional theories are often accused of being messier and more complicated. Fine reverses the accusation. He says that yes, the underlying logic may be richer, but that richness can purchase a more useful simplification elsewhere.
Williamson takes a very different line. He defends an intensional theory built on possible worlds semantics. Possible worlds semantics is a framework, developed most famously by Kripke and Barcan Marcus and others, in which we understand necessity, possibility, properties, and propositions by looking at what holds across different possible worlds, different ways things might have been. Williamson likes this framework because it is simple, well developed, widely used, mathematically clear, and known to be consistent. He is not denying that language can contain hyperintensional devices in some trivial sense. Quotation marks, for example, obviously distinguish between different wordings even when those wordings mean the same thing. “‘Cat’” and “‘feline’” refer to different words. But that does not tell us anything deep about the structure of reality. It just shows that language can talk about language. Williamson is happy to set such cases aside. His concern is with cases where philosophers claim that language reveals finer distinctions in the world itself.
His central warning is about projection. Projection means taking a feature that belongs to language, wording, or discourse and mistakenly attributing it to reality itself. This is one of his major objections to hyperintensionalism. He gives the example of explanatory “because.” Someone might say, “The statement that grass is green is true because grass is green.” That sounds right. But “Grass is green because the statement that grass is green is true” sounds wrong, as though the order of explanation has been reversed. At first glance this seems to support hyperintensionalism. The two clauses on either side are necessarily equivalent, yet the two “because” statements do not seem equally acceptable. So perhaps explanation is hyperintensional. But Williamson says we must be cautious. There are structurally similar cases where our intuitions are clearly being misled by superficial wording. He uses the example of “furze” and “gorse,” two words for the same plant. “Furze is as prickly as gorse because furze is gorse” seems like a reasonable explanation. But “Furze is as prickly as gorse because furze is furze” sounds silly. If one followed the hyperintensional impulse, one might say the first “because” statement is true and the second false. But that would be absurd, because “furze” and “gorse” mean the same thing. There is no genuine difference in meaning here, just a difference in words.
So why do we judge the two cases differently? Williamson says we are relying on a heuristic. A heuristic is a quick, practical rule of thumb, useful but not perfectly reliable. In this case, we assess “A because B” partly by asking whether the sentence B would be a helpful answer to the question “Why A?” “Furze is gorse” is helpful because it tells the hearer that the two names pick out the same plant. “Furze is furze” is unhelpful because it tells them nothing new. But that is a difference in communicative usefulness, not necessarily in truth conditions or metaphysical structure. So our intuition is reacting to explanatory usefulness, not to a real difference in the propositions themselves.
Williamson thinks many apparent motivations for hyperintensionalism arise from mistaking pragmatic differences, differences in how informative or useful a sentence is, for semantic or metaphysical differences. That is his charge of projection. He makes a similar point with aboutness. Hyperintensionalists often want to say that the proposition “Mary is guilty or not guilty” is about Mary, while “John is guilty or not guilty” is about John. Since one is about Mary and the other about John, they must differ. But Williamson says that by intensional standards, both are just logical truths. Each is true in every possible world. So there is no worldly difference between them. “Aboutness,” he argues, is fundamentally a property of discourse, of what we are talking about, not a deep feature of propositions themselves. Again, the hyperintensionalist, in his view, is projecting something linguistic onto the world.
Fine replies that from within his truthmaker picture, the “aboutness” of “Mary is guilty or not guilty” need not be a mere projection from language. The sentence can be made true via ways involving Mary’s guilt or Mary’s innocence. Those truthmaking routes are unproblematically about Mary. So the larger sentence is also about Mary. The difference, on his view, comes not from surface wording but from the pattern of facts connected to the sentence. That is why so much in the debate turns on truthmaking. Fine believes it lets him ground hyperintensional distinctions in the world, or at least in a disciplined semantic framework, rather than merely in verbal clothing.
Williamson attacks truthmaker theory itself. He grants that truthmaking seems natural in a few simple cases. A disjunction can be made true by one of its disjuncts. A conjunction can be made true by both conjuncts together. An existential statement such as “There is a pen on the table” can be made true by an instance, namely that pen. But he thinks the theory breaks down when one tries to generalise it. His examples are negative and universal claims. What makes “It is not snowing” true? Is there a negative fact out there in the world, the fact of not snowing? That sounds metaphysically strange. Or what makes “There are no dragons” true? Do we have to list every non-dragon in the universe and then add that there is nothing else? Williamson thinks this becomes awkward, ad hoc, and possibly circular. So he worries that truthmaker theory begins with attractive local examples but fails as a general theory.
Fine says truthmaker semantics is a semantics, not necessarily a metaphysics. That is an important distinction. He is not always claiming that the truthmakers are literally deep items in the furniture of the universe. He is saying that a semantic framework organised in terms of truthmakers can still be useful even if one is flexible about what truthmakers are. Second, he suggests ways of handling harder cases, including negative and universal ones, though he acknowledges these are difficult. At one point he mentions “generic truthmakers,” which are somewhat unorthodox devices not straightforwardly located in the world. This shows both the creativity of his view and the kind of complication Williamson worries about.
The discussion of counterfactuals brings out a further basic divide.Williamson sees counterfactuals as a kind of modality. The “would” in “if it were that P, then Q would be the case” functions like a local necessity operator: in all the relevant possible worlds where P holds, Q also holds. Once you see counterfactuals this way, it is unsurprising that embedding them will not generally collapse into simpler forms. Nesting one necessity inside another often changes things. In modal logic, piling up modalities can lead you to further layers of possible worlds. So for Williamson, Fine’s demand for normal forms is not something we should expect in a general semantics of counterfactuals.
Fine’s answer is that he is not primarily trying to capture every subtlety of natural language. He is interested in a regimented language, a cleaned up formal language designed for certain purposes. “Regimentation” in philosophy means revising ordinary language into a more precise, disciplined form, much as first order logic regiments ordinary uses of “all,” “some,” “and,” and “or.” Within such a formalised setting, he thinks it is desirable to allow rich embedding but also to have a theorem telling us that every complex counterfactual can be rewritten in a perspicuous normal form. “Perspicuous” here means clear in structure, transparent, easy to see through. So the dispute is not only about what natural language does, but about what kind of formal framework philosophy should build.
They also discuss imperatives, commands such as “shut the door,” and conditional imperatives such as “if there is a draft, shut the door.” Fine thinks imperatives naturally connect with plans: instructions for what to do under different circumstances. He suggests that hyperintensional resources may help model complex, embedded practical reasoning. Williamson is less convinced. He thinks one can often understand such conditionals in simpler ways and does not see the need to invoke a richer hyperintensional apparatus unless forced.
The disagreement is methodological as well as technical. Williamson openly says that he gives a lot of weight to simplicity, elegance, stability, and the track record of a framework. When there is a conflict between a simple theory that works well and some intuitive counterexample, he is suspicious of the counterexample. He thinks our intuitions are often guided by heuristics, and heuristics can mislead. So one should not too quickly complicate a successful theory.
Fine agrees that simplicity matters, but he is much less suspicious of intuition. He thinks philosophy often progresses by paying close attention to specific cases that reveal something important, rather than by enforcing a general theory from above. He does not deny the value of large frameworks, but he worries that philosophy is not always in the same position as physics, where a beautiful simple theory may earn the right to override local complications. In philosophy, he says, one often has to work upwards from carefully judged particular cases.
This shows that the argument is not only over propositions, properties, or truthmakers. It is also over how to do philosophy well. Williamson thinks: start with a powerful, unified, disciplined framework unless forced away from it. Fine thinks: be more willing to let troublesome cases teach you that the framework is missing something. Neither is rejecting theory, and neither is embracing chaos. But they weight virtues differently. There is also an interesting meta-level discussion about Kripke. Williamson points out that intensional modal logic underwent a major transformation when Kripke provided a clear, systematic possible worlds semantics. It solved technical problems, unified the field, and spread into linguistics, computer science, economics, mathematics, and beyond. Hyperintensionalism, by contrast, still lacks one canonical framework accepted across the board. There are many systems, many proposals, and no single unifying breakthrough of comparable force.
Fine largely concedes this. He says hyperintensionalism may still be waiting for its Kripke. That is a generous admission. He does not pretend the field is as settled or as unified as intensional modal logic. But he also notes that modal logic itself looked messy before its own consolidation. So lack of convergence at this stage does not, in his eyes, show that the project is hopeless.
Williamson stresses that possible worlds semantics works not only in philosophy but in probability theory and in many scientific frameworks. This matters to him because it shows that intensionalism is not some bizarre philosopher’s invention. It fits with robust, widely useful mathematical structures. Fine replies that hyperintensional tools, especially truthmaker semantics, are increasingly being applied in AI and linguistics, and that he himself was partly motivated by problems in AI, including the frame problem, which concerns how to represent what changes and what stays the same when an action occurs. He suggests that hyperintensional distinctions may prove useful wherever one needs finer control over relevance, explanation, and dependence than possible worlds semantics provides.
Near the end they move to normativity, which shows how the debate reaches beyond logic. A student asks about moral language, such as “wrong.” Williamson says that even if some act is necessarily wrong, that does not mean the normative and the non-normative differ at the level of worldly property. If “torturing babies for fun” is necessarily wrong, then “torturing babies for fun” and “wrongly torturing babies for fun” may pick out the same property. But he insists that this does not commit him to reducing morality to something non-moral. His point is only that differences in vocabulary do not automatically reveal differences in the things described. Again, do not project linguistic distinctions onto metaphysics.
Fine replies by drawing a distinction between kinds of necessity. This is another key Finean move. He says the necessity involved in moral claims may be normative necessity rather than metaphysical necessity. Metaphysical necessity concerns what could or could not have been the case in the deepest structure of reality. Normative necessity concerns what must be the case from the point of view of what ought to be done or valued. Fine thinks one should not assume that every necessity is of the same kind. This is characteristic of his broader philosophical style. He often argues that apparently unified categories, like necessity, essence, or consequence, need to be broken up into more discriminating kinds.
The very end of the exchange, where they discuss intuitionistic logic, reinforces the contrast in temperament. Fine points to his truthmaker semantics for intuitionistic logic as a case where hyperintensional ideas illuminate relations between previously separate approaches. Williamson grants that studying such logics can be illuminating, but he sharply remarks that they may illuminate philosophically mistaken views. This is classic Williamson, crisp and sceptical. Fine then gives a more charitable defence: even if the original ideology behind intuitionistic logic was flawed, the logic itself can still be useful, especially for exploring constructive proof, proof that actually builds or exhibits what it claims exists rather than merely showing indirectly that it must exist.
Probably the best way to understand the whole debate is to see that both philosophers care about discipline, clarity, and formal structure, but they disagree about how fine grained our logical and semantic tools need to be. Williamson thinks the possible worlds framework is already an extraordinarily powerful instrument. It is simple, general, mathematically mature, and capable of capturing a huge amount. He worries that hyperintensionalism often mistakes verbal or pragmatic subtleties for differences in reality. He also worries that richer frameworks become unstable, fragmented, and vulnerable to paradox unless one keeps adding complications.
Fine thinks possible worlds semantics throws away distinctions that really matter. Necessary equivalence is too crude a standard for sameness. Explanation, aboutness, permission, counterfactual reasoning, dependence, and related notions often require a finer mesh. He thinks truthmaker semantics offers one principled way to capture those differences, and he insists that richer logic can sometimes reveal a deeper structural simplicity, not merely produce clutter.
So the dispute is really about granularity. How coarse or fine should our account of meaning and reality be? If you imagine two maps of the same territory, Williamson’s map is elegant, broad, and powerful. It shows the major structures and allows one to navigate widely and efficiently. Fine’s complaint is that for some purposes that map leaves out distinctions that matter, distinctions between routes, supports, and structures that are invisible at that scale. He wants a map with more detail. Williamson replies that once one draws too much detail, one risks confusing features of the map with features of the land.
That is why the debate remains philosophically alive. It is about what philosophy should count as a real difference, what kind of evidence should move us, how closely semantics should tie itself to metaphysics, and whether the pressure of local examples justifies expanding our ontology or our logic. Fine’s side says, in effect, that necessarily equivalent is not always enough for genuine sameness. Williamson’s side says that once you go beyond necessity and possibility, you must be very careful not to import into reality distinctions that belong only to how we speak, explain, or think.
(This nicely links with a discussion I've been developing in philosophy of education here in case you're interested)