Thursday, 17 September 2020

On the Need to Distinguish Knowledge of Essential Properties from the Knowledge That They Are Essential

In one of my favourite papers about modal metaphysics, Rosen's 'The Limits of Contingency', Rosen develops the idea that there are two sets of modal notions which are apt to be conflated under the heading 'metaphysical modality'. Roughly: a correct conceivability modality, and a more properly metaphysical modality on which some things which are correctly conceivable are in any case not really possible.

In a recent paper, 'Correct Conceivability and its Role in the Epistemology of Modality' whichin a new book Les Principes Métaphysiques published by the College de France, Robert Michels considers an objection to Rosen's idea of a correct conceivability modality construed as giving an account of how considerrations about conceivability can takes us from non-modal to modal knowledge. I think this objection is based on a misunderstanding, as I will explain in this post. 

Let me quote from Michels, first to set the scene, and then to see the objection and the main responses Michels considers.

Correct Conceivability

The basic idea

10The correct conceivability-approach presupposes the Kripkean standard view of metaphysical modality and accordingly has to rule out modal errors, cases in which a state of affairs is conceivable, but not metaphysically possible. How this is done is nicely explained in the following mock-quote of Rosen’s “others”:

If the ancients could conceive a world in which water is an element, this is only because they were ignorant of certain facts about the natures of things. In particular, it is because they did not know what it is to be water. They did not know that to be water just is to be a certain compound of hydrogen and oxygen – that to be a sample of water just is to be a quantity of matter predominantly composed of molecules of H2O. This is not to say that they did not understand their word for water. But it’s one thing to understand a word, another to know the nature of its referent. The ancients could see no contradiction in the supposition that water is an element because they did not know that water is a compound by its very nature. But we know this; and given that we do, we can see that to suppose a world in which water is an element is to suppose a world in which a substance that is by nature a compound is not a compound. And that’s absurd. (Rosen 2006, p. 22-23)

11The idea is hence that in order to avoid modal error, conceivability needs to be supplemented by knowledge of the natures, or equivalently, essences of relevant entities, in this case the essence of (the property of being) water. Equipped with this knowledge, the conceiver is able to detect that the assumption that water is an element together with essential truths about the relevant entity entails an absurdity.

12The correct conceivability-approach hence gives us a simple and elegant explanation of why we are apt to make modal errors and a recipe for ruling them out. We tend to commit modal errors because we can conceive of states of affairs which are ruled out by relevant essences. To avoid these errors, we have to let our ability to conceive be guided by knowledge of the essences of relevant entities.

An objection to essence-based conceivability approaches and how it can be addressed

13There is a rather obvious objection to the correct conceivability-approach which should be mentioned: The approach crucially relies the conceiver having knowledge of essence, but essence itself is a modal notion. Doesn’t this mean that the notion of correct conceivability cannot answer the core question of modal epistemology, the question of how we can acquire modal knowledge?

  • 5 See for example Lowe (2012), Hale (2013, ch. 11), Tahko (2016), Tahko (2017). For a recent critical (...)


(End of quote.) 

Michels considers a number of responses, but not the following simple one which I think is correct.

Yes, the approach relies on the conceiver knowing that some thing has a property, where arguably that property is in fact an essential property of the thing. But the approach does not rely on the conceiver knowing that the thing essentially has that property.

The idea is not that people learned that water is essentially H2O and then on that basis, saw that water being simply an element is not correctly conceivable. Rather, they just learned that water is H2O, and then on the basis of their grasp of how the concept of water works, saw that water being an element is not correctly conceivable. The knowledge of essence, just like the knowledge of necessity (Fine taught us to disinguish the two), may perhaps also be accounted for along similar lines. But that's by the by. This objection simply doesn't get off the ground as far as I can see. 

This sort of confusion is not unique to Michels's paper. Phrases like 'knowledge of essence' and 'knowledge of necessity' are apt to blur this important sort of distinction, leading to mistakes in the epistemology of modality. 


Michels, Robert. Correct Conceivability and its Role in the Epistemology of Modality In : Les principes métaphysiques [en ligne]. Paris : Collège de France, 2020 (généré le 18 septembre 2020). Disponible sur Internet : <>. ISBN : 9782722605350. DOI :

Rosen, Gideon (2006). The limits of contingency. In Fraser MacBride (ed.), Identity and Modality. Oxford University Press. pp. 13--39.

Thursday, 14 May 2020

On Family Resemblance Concepts

I want to clarify some aspects of the celebrated Wittgensteinian idea of a family resemblance concept.

Are all family resemblance concepts such that no single feature is shared by all the things to which the concept applies?

Some of Wittgenstein's formulations, and explanations based upon them, would suggest an affirmative answer. But I think that a more general, useful notion of a family resemblance concept should not require this.

It should disqualify a concept for family resemblance status that some feature happens to be common to all the things that fall under the concept. It may be that this feature does not sufficiently characterise the things as falling under the concept. That is, just because you can give necessary conditions for the application of a concept, does not mean its application is not based on the kind of criss-crossing network of similarities that Wittgenstein has us imagine. This passage gets it right:
we extend our concept of number as in spinning a thread we twist fibre on fibre. And the strength of the thread does not reside in the fact that some one fibre runs through its whole length, but in the overlapping of many fibres. (PI §67)
This makes it clear that there may still be a single fibre running through the thread. It's just that that alone isn't responsible for the strength of the thread.

Are all concepts which do not admit of non-trivial analysis in terms of necessary and sufficient conditions family resemblance concepts?

It seems to be a necessary condition on family resemblance concepts that they do not admit of non-trivial analysis in terms of necessary and sufficient conditions. But it doesn't seem to be a sufficient condition. That is, it seems that there are concepts which do not admit of this sort of analysis and yet are not what we would think of as family resemblance concepts. For example:

  • Certain primitive, i.e. undefined, concepts in theoretical use are not family resemblance concepts. For example, the concept of a lever (insofar as it isn't defined).
  • A concept that is undefined but very closely tied to experience, e.g. the concept of red.
  • Concepts which by design only apply to one thing, such as the concept of God - or, for that matter, just your concept of some particular person you know. (The whole idea of 'individual concepts' is a bit neglected though, and may not strike the reader as being in good standing.)

These do not seem to count as family resemblance concepts, because while they do not admit of non-trivial airtight definitions, there does not seem to be the sort of heterogeneity among the things that they apply to that characterises family resemblance concepts as discussed by Wittgenstein.

This last category, however, invites another question...

Diachronic family resemblance concepts?

It would seem that the concept of a particular person can't be a family resemblance concept in the sense of many different things falling under it not because of a common feature but because of overlapping similarities, because at most one thing does fall under it. But if we consider the individual through time, we start to see the possibility for something like the family resemblance idea applying to the concept of a particular person.

Is 'family resemblance concept' a family resemblance concept?

I think there's potential for a negative answer. At least, it seems to me we can give a precisified version of the idea that is not itself a family resemblance concept. On the other hand, perhaps such a thing would fail to capture the idea in full.

Friday, 20 March 2020

Opportunism and Fastidiousness in Language

Many, probably most, intelligent speakers and thinkers are linguistic opportunists. They treat words and phrases as tools to convey things that they are already thinking in proto-linguistic or rough linguistic form, and if some construction seems likely to do the conveying job, they use it. 

Linguistic opportunism is higher in private communication than in public, and higher in informal writing than in formal writing. The opposite of linguistic opportunism is linguistic fastidiousness. Analytic philosophy is characterised by high linguistic fastidiousness, while other types of philosophy are often linguistically opportunistic.

Certain moves that may at first seem like moves of fastidiousness belie an underlying opportunism. For example, an linguistic opportunist may abandon a formulation and self-correct to a formulation which lets their underlying message come through clearly, where a stickler may take the time and effort to clarify the sense in which what they said was correct although potentially misleading.

(I heard an example of this in an episode of Dan Carlin's Hardcore History podcast, but I can't remember the details. Carlin is an interesting example of a fairly fastidious opportunist. As I see it, his underlying goal makes him fundamentally an opportunist. His goal is to paint pictures with words, to move the listener, and to convey history. But he often becomes self-conscious about language. Nevertheless, this is all kept in the service of the goal, and so does not go into niceties that the true stickler would go into.)

What drives the stickler? In large part and in many cases, their motivation takes the form of an intrinsic interest in language and fine distinctions. (But remember, one may ask why such an interest should ever arise in the first place.) As someone with marked stickler tendencies myself - tendencies which have at certain points in my development reached nearly pathological levels - there are many times when I have become interested in some linguistic or conceptual issue raised by some construction that has been used, where this definitely only detracts from the task of staying on-message. But sticklerhood is not always like this. Sometimes it is motivated by real, felt concern with the ongoing adequacy of the linguistic resources to the task at hand. 

Even the purer form of sticklerhood, which unambiguously cuts against the grain of achieving the purpose of the discourse from which it arises, may have a justification beyond the intrinsic interest of reflecting on language and concepts. The stickler may be seen as concerning themselves with utility too. Not with having the right tools for the task at hand, but with maintaining a large, powerful toolkit for whatever may come next. And sometimes this goal may be in conflict with an opportunistic strategy which would work well for current purposes.

It may seem self-evident that the linguistic opportunist is a friend of linguistic innovation, the fastidious stickler a foe. But this is too quick. By maintaining order and consistency, the stickler helps to cultivate an environment in which buildings can be erected which, if the opportunist held sway, would crumble into confusion. 

Friday, 10 January 2020

Forthcoming in Thought: The Accident of Logical Constants

View Table of Contents for Thought: A Journal of Philosophy volume 8 issue 4

The Accident of Logical Constants

Work on the nature and scope of formal logic has focused unduly on the distinction between logical and extra-logical vocabulary; which argument forms a logical theory countenances depends not only on its stock of logical terms, but also on its range of grammatical categories and modes of composition. Furthermore, there is a sense in which logical terms are unnecessary. Alexandra Zinke has recently pointed out that propositional logic can be done without logical terms. By defining a logical-term-free language with the full expressive power of first-order logic with identity, I show that this is true of logic more generally. Furthermore, having, in a logical theory, non-trivial valid forms that do not involve logical terms is not merely a technical possibility. As the case of adverbs shows, issues about the range of argument forms logic should countenance can quite naturally arise in such a way that they do not turn on whether we countenance certain terms as logical.

Pre-print available at PhilPapers

Friday, 13 December 2019

Tractarian Propositions and Taking the 'X in Y' Construction Seriously

This is a sequel to the previous post, in which I continue to react to interesting recent "cognitive act theories" of propositions championed by Soames and Hanks, and work out my own views in relation to them.

In Soames's recent article on the Tractatus, he argues that Wittgenstein's conception of a proposition - that it is a propositional sign in its projective relation to the world - is incoherent. Soames's idea is that this doesn't actually specify a thing over and above the propositional sign. Just as Soames-in-relation-to-his-wife (one of his examples) isn't actually a separate thing or person from Soames, a propositional sign in its projective relation to the world isn't actually something other than the propositional sign. It is not some "larger" entity which includes the propositional sign as a part.

This then leads Soames to propose, on the basis also of a remark in the Tractatus that our thinking the sense of a proposition is our putting it in relation to the world, that Wittgenstein would have been better off identifying propositions as propositional signs together with cognitive acts. And this is similar to his own recent theory of propositions, on which they are just cognitive acts in abstraction from any particular signs. 

In this way, Soames presents Wittgenstein as groping toward a better view of the nature of propositions - better than those of Frege and Russell, for whom propositions were Platonic things independent of language use - and offering a more coherent way of doing this.

Recently Peter Hanks has argued that there is another way here: that we can instead look at the (to me confusing and confused) idea in the Tractatus that a propositional sign is a fact. (This is something Wittgenstein later came to think of as a category mistake - but the new act theorists of propositions are generally disposed to be less keen to convict philosophers of category mistakes. After all, the view that a proposition is an act - a thing done - itself sounds like a category mistake. So we're in a pocket of philosophy where there's a fair amount of tolerance of what can seem like category mistakes, being explained away in terms of unimportant intuitions that should be overcome as we better systematise out thinking.) Looking at it that way, Hanks argues that the propositional sign in its relation to the world may be seen as a "larger" fact which involves the fact that is the propositional sign, but where the elements of that sign/fact that are related to one another are also related to further elements, things out in the world. 

I share Hanks's sense that Soames's argument against the coherence of Wittgenstein's conception of propositions and how they relate to propositional signs is surmountable. But I confess that the idea of a sign as a fact has never appealed to me, and really does seem like a category mistake. 

I think there's a third way to understand this talk of a proposition being a propositional sign in its projective relation to the world. It may even be more faithful to the Tractatus, but maybe not. I think it probably is more faithful to Wittgenstein's ideas as they developed after the Tractatus though. More importantly, I think it may be the best way of thinking about these matters.

Soames complains that a thing in some relation isn't actually a separate thing. And this is meant to be an objection to the Tractarian notion of a proposition, the idea being that propositions are meant to be distinct things from propositional signs. 

But who said they had to be? The objection I have to both Soames's and Hanks's reconstructions of the Tractarian idea is that they both look for a way to avoid taking the 'X in Y' construction seriously, whereas part of what makes it a truly radical and fruitful idea may get lost that way. (The new act theorists want propositions to be inherently representational things. But perhaps part of Wittgenstein's thinking is that really we have signs, and we use them, and it is only in those uses that they bear representational properties and properties like truth. And so looking for a further object over and above the sign is unnecessary, and even a mistake.)

Now, there are different ways to think about how this conception can be expressed, and how expressions of it can be decomposed. You might think of it this way: there's a complex sign, which may get used in two different language systems. Then you might think that this sign is true in one of its projective relations to the world, and false in another. Here the 'in projective relation R' becomes part of the predicate, like 'true-in-L' in discussions of Tarski. But you can also put it into the subject, 'The sign in relation R' and then predicate truth of the sign in that relation. Is this a further entity over and above the sign? You can think of it that way, but perhaps there's another way here, where we just have the property of truth - not some more complicated projective-relation-involving predicate - and we just have the sign as our main entity. But we nevertheless predicate truth not of the sign simpliciter but we predicate it of the sign in a particular projective relation to the world. On this conception, it's not that we have an augmented predicate or a thing over and above the sign, rather we're just using a logical form which isn't just a simple subject-predicate proposition of the sort whose truth conditions can be given as: the proposition is true iff the property expressed by the predicate is possessed by the entity denoted by the subject. To squeeze the Tractarian conception of propositions into that form is to water it down. In particular, it is to water down its ability to get around the problem laying at the foundation of the new act-based theories of propositions - the problem about propositions needing to be inherently representational. Taking the Tractarian idea of a proposition more seriously, we don't have to find a thing that is inherently representational and then put that at the basis of our theories. We may insist that the primary truth bearers really are signs, but that these signs only bear truth in use, and that a given sign can bear truth in one use and falsity in another. 


Hanks, Peter (2019). Soames on the Tractatus. Philosophical Studies 176 (5):1367-1376.
Soames, Scott (2016). Propositions, The Tractatus, and "The Single Great Problem of Philosophy". Critica 48 (143):3-19.

Sunday, 8 December 2019

Against Inherently Representational Anything

Soames, in his fascinating recent work Rethinking Language, Mind, and Meaning, begins by posing a problem for the study of meaning and language as developed by philosophers and logicians in the Twentieth Century.

For propositions to play the theoretical roles assigned to them - such as being the primary bearers of truth, being the objects of propositional attitudes like belief and desire, being the contents of mental and perceptual states, and being the meanings of some sentences - they, Soames says, must be inherently representational. That is, they must impose conditions on the world off their own bat, so to speak. 

But, argues Soames, the sorts of things that traditionally play the proposition role in modern theories do not seem to be inherently representational. Soames provides 'reasons to believe that no set-theoretic construction of objects, properties, world-states or other denizens of Plato’s heaven, could ever be inherently representational bearers of truth conditions in this sense' (Rethinking, Ch. 2).

This leads Soames to his new theory of propositions, on which they are cognitive acts of a certain kind. ('Suppose, however, we start at the other end, taking it as an uncontested certainty that agents represent things as being certain ways when they think of them as being those ways' (Rethinking, Ch. 2).) For example, the proposition that snow is white, on Soames's theory, is the act of predicating whiteness of snow. These cognitive acts, according to Soames, are inherently representational, which means that they could be able to play the role of propositions. 

(Soames says that, at bottom, it is language users that represent things as being certain ways, and they do this by performing cognitive acts, which acts may derivatively be said to represent. But although, in this way, they represent in a derivative sense, they do so inherently - and that is the crucial point for Soames, that makes cognitive acts fit to play the role of propositions.)

I am very heartened to see Soames realising that his earlier, broadly Russellian conception of propositions won't do and looking for an alternative. But his cognitive acts seem a bit mysterious to me. In this note I won't try to refute Soames's new theory of propositions, but let me say something briefly about what worries me. It's not so much that I think that there's no such thing as the cognitive act of predicating whiteness of snow, but I don't feel like this is the sort of thing that is fit to play the sort of basic explanatory role that Soames wants it to play. It feels too much like a black box containing important workings for that. Treated as something basic, it feels occult or magical. (Wittgenstein in the Investigations seems very concerned to avoid positing mental goings-on that are meant to play this kind of foundational role in explaining representation. This has influenced me and I think there's something right about Wittgenstein's conviction that this is not the way forward.)

There is another conception of propositions, on which they are sentences (of a certain kind) in use (or a certain kind of use). For instance, in the Tractatus Wittgenstein said that a proposition is a propositional sign in a projective relation to the world. (In a recent paper I sketch an account of propositions that treats them similarly.)

(Of course, it is nice to be able to say what two synonymous sentences in different languages have in common, and often it is said that they 'express the same proposition'. On the present approach, they may be said to have the same use, the same meaning. But ultimately it is not just the use or the meaning that represents - it is a sign in use, a sign with meaning, that does this. The "proposition" or "statement" or whatever you call it that two different sentences express is an abstraction from the particular propositions that are alike in meaning.)

It seems to me that this fundamental logical move of treating propositions not as things by themselves, as it were, but a certain kind of thing in a certain kind of context is very important, and constitutes the right way to avoid the twin pitfalls of having propositions be things that don't themselves represent, and of having them be explanatorily basic cognitive acts. 

Admittedly, sentences in use can't just be slotted in to all the roles Soames delineates without further ado. For instance, we probably don't want to say that if you believe something - perhaps without even representing it to yourself linguistically - the thing you believe is a sentence in a particular use. Soames's theory may have an advantage over my approach here in having this one kind of thing - propositions - playing all of these roles (although I doubt it, since Soames's theory has predictions which sound like category-mistakes, such as that one may 'perform a proposition', propositions being acts according to this theory). But I think that ultimately such a theory with one single sort of thing playing all these diverse roles will not be attractive overall, and that we may have to refine the picture somewhat of how these things like sentence meaning and the objects of belief relate to each other. I am focusing for now on linguistic meaning.

Sentences in use, you might say are 'inherently representational': but the whole idea of inherence doesn't really fit here. The whole point is that sentences are not inherently representational, but used in certain ways, they are. If you want to treat the sentence-in-use as a sort of thing by itself, then this is a kind of abstraction. Such a logical construction may be useful, but the resulting entity is not explanatorily basic: underneath, you have the sentence and you have all the stuff about how it is used. And so, at the base level, you don't have anything inherently representational.

This approach fits naturally with the ideas of representing and of a representation. Fundamentally, a representation itself is just a concrete thing - like a drawing or a sentence. And it represents not inherently, but by being used in a certain way. People represent things as being certain ways by putting representations to use.

This approach also furnishes a kind of explanation of the feeling of occultness or suspiciousness in theories which posit inherently representational entities in their explanatory base: they feel unsatisfactory because they hide the contextual rabbit in the hat of some posited object. If we are forced to treat this object as basic, we can never see under the hat.


Haze, Tristan Grøtvedt (2018). Propositions, Meaning, and Names. Philosophical Forum 49 (3):335-362.

Soames, Scott (2015). Rethinking Language, Mind, and Meaning. Princeton University Press.

Wittgenstein, Ludwig (1922). Tractatus Logico-Philosophicus. Routledge & Kegan Paul.

Saturday, 2 November 2019

‘Two Recent Theories of Conditionals’ vs. Two Recent Theories of Conditionals

The tide is beginning to turn against counterintuitive theories of indicative conditionals which either deny them truth-values or give them apparently wrong ones, but a deductive argument in Gibbard’s 1981 paper ‘Two Recent Theories of Conditionals’ appears to show that those unhappy options are the only viable ones. Here I summarise some fascinating recent technical work on an escape route and argue that Gibbard’s reason for not taking that route stemmed from a (forgivable) failure of theoretical imagination and a too-narrow view of the motivation for granting truth-values to indicatives.
Indicative conditionals seem to have truth-values. Just as ‘I will not eat a grapefruit tomorrow’ and ‘You are a horse’ are true and false respectively, so it seems that ‘If I have breakfast tomorrow, it won’t be a grapefruit’ and ‘If tomorrow someone tells you you’re a horse, you’ll become a horse’ are true and false respectively.
It also seems that an indicative conditional does not always have the same truth-value as the corresponding material conditional (which is true in all cases except when the antecedent is true and the consequent false). For example, both ‘If you die tonight, you’ll be alive tomorrow’ and ‘If you die tonight, the French Government will collapse tomorrow’ seem false - the first due to the nature of life and death, the second due to the way the world is organized - even though ‘You will die tonight ⊃ you’ll be alive tomorrow’ and ‘You will die tonight ⊃ the French Government will collapse tomorrow’ are both true provided that you don’t die tonight.
An ingenious deductive argument from Allan Gibbard’s 1981 paper ‘Two Recent Theories of Conditionals’ appears to show that these two seemings cannot both be right. Gibbard’s collapse argument is so called because threatens to collapse any truth-conditions that an indicative conditional might have down to those of the corresponding material conditional.
But Gibbard’s argument does not by itself demonstrate collapse, and the larger context of Gibbard (1981) shows that he was aware of that fact. Indeed, he identified an escape route - one which takes some noticing, and may not be noticed by many who encounter this much-discussed argument outside the context of Gibbard’s paper. However, upon identifying the escape route Gibbard gave what may seem like a compelling reason not to take it. Having also rejected the material conditional account of indicatives, Gibbard ends up adopting the NTV thesis - the view that indicative conditionals lack truth-values.
Subsequently, theories which take the escape route Gibbard identified have been pursued in earnest anyway, with impressive results. After a period in which the NTV thesis was beginning to look like the dominant view, the tide is finally beginning to turn.
The purpose of this article is to contribute to turning the tide by confronting and neutralizing Gibbard’s reason for not taking the escape route, and along the way to provide a high-level summary of some recent relevant work (some of which can be highly technical). We will see that by drawing on this work we can uphold, in a principled way, the intuitive view that indicative conditionals do indeed have truth-values, and ones which can differ from those of the corresponding material conditionals.
1. Gibbard’s Collapse Argument
I begin with a reader-friendly reconstruction of Gibbard’s collapse argument.
If Implies Hook: An indicative conditional ‘If A then C’ always implies ‘A ⊃ C’, i.e. indicatives are at least as strong as material conditionals.
Conditional Conjunction Elimination: All indicative conditionals of the form ‘If (A & C) then C’ are logical truths.[1]
Import-Export: In any arbitrary context, all pairs of indicative conditionals of the forms ‘If A then (if B then C)’ and ‘If (A & B) then C’ are logically equivalent.
Equivalent Antecedents: In any arbitrary context, all pairs of indicative conditionals which share the same consequent, and whose antecedents are logically equivalent, are themselves logically equivalent.
Consider any arbitrary indicative conditional ‘If A then C’ in an arbitrary context and its corresponding ‘A ⊃ C’.
By Conditional Conjunction Elimination, ‘If (A & C) then C’ is a logical truth.
By Equivalent Antecedents, ‘If ((A ⊃ C) & A) then C’ is then also a logical truth, since ‘A & C’ is logically equivalent to ‘(A ⊃ C) & A’ by propositional logic.
By Import-Export, ‘If (A ⊃ C) then (if A then C)’ is then also a logical truth. (Here ‘(A ⊃ C)’ plays the ‘A’ role in Import-Export as stated above, ‘A’ plays the ‘B’ role, and ‘C’ plays the ‘C’ role.)
By If Implies Hook, ‘(A ⊃ C) ⊃ (if A then C)’ is then also a logical truth, since the implications of logical truths are logical truths.
By If Implies Hook again, ‘(If A then C) ⊃ (A ⊃ C)’ is a logical truth.
By propositional logic applied to the last two sentences, ‘(If A then C) ≡ (A ⊃ C)’ is a logical truth. Hence, any arbitrary indicative conditional in any arbitrary context is logically equivalent to its corresponding material conditional. QED.
If we accept the reasoning and want to maintain that indicatives have truth-values that don’t always agree with the corresponding material conditional, we need to reject one of the assumptions of the argument - either one of the explicit ones listed above, or some auxiliary assumption.
2. The State of the Art of Resisting Collapse
Some have suspected Import-Export. For instance, a detailed axiomatic analysis of Gibbard’s proof leads Fitelson to conclude as follows:
The only axioms that seem plausibly deniable (to me — in the context of a sentential logic containing only conditionals and conjunctions) are [...] the import-export laws, and they seem to be the most suspect of the bunch. I find it difficult to see how any of the other axioms could (plausibly) be denied (but I won’t argue for that claim here). (Fitelson (2013), p. 184.)
However, Import-Export has proven difficult to reject. It strikes many as plausible, and counterexamples have been elusive. Edgington, for instance, finds them plausible in the abstract, and suggests that any example one tries seems to obey the principle:
Here are two sentence forms instances of which are, intuitively, equivalent:
(i) If (A&B), C.
(ii) If A, then if B, C.
(Following Vann McGee (1985) I'll call the principle that (i) and (ii) are equivalent the Import-Export Principle, or “Import-Export” for short.) Try any example: “If Mary comes then if John doesn't have to leave early we will play Bridge”; “If Mary comes and John doesn't have to leave early we will play Bridge”. “If they were outside and it rained, they got wet”; “If they were outside, then if it rained, they got wet”. (Edgington (2014), Sec. 2.5.)
There is one notable attempt at a counterexample in the literature, due to Kaufmann (2005, pp. 213 - 214). In Fitelson’s (2016) presentation:
Suppose that the probability that a given match ignites if struck is low, and consider a situation in which it is very likely that the match is not struck but instead is tossed into a campfire, where it ignites without being struck. Now, consider the following two indicative conditionals.
(a) If the match will ignite, then it will ignite if struck.
(b) If the match is struck and it will ignite, then it will ignite.
It seems like it is possible to understand (a) and (b) in such a way that (a) expresses a logical truth and (b) does not, suggesting that they may not be equivalent, making for a counterexample to Import-Export. But this has been challenged. Khoo and Mandelkern (forthcoming) write:
However, we suspect the intuitive grip of this example rests on an equivocation in ‘will’ between a broadly dispositional meaning and a temporal meaning. We can disambiguate these readings by replacing ‘will ignite’ with ‘is ignitable’, to select for the dispositional meaning, and by replacing ‘will ignite’ with ‘will ignite at t’, to select for the temporal meaning. (We also replace ‘struck’ with ‘struck at t0’, to thoroughly regiment the readings.) We suspect that the reading on which (a) and (b) strike us as inequivalent is:
(a’) If the match is ignitable, then it will ignite at t if struck at t0.
(b’) If the match is struck at t0 and it will ignite at t, then it will ignite at t.
(b’) does indeed strike us as a logical truth, while (a’) certainly does not. But this pair is of course no longer a counterexample to the pattern we are exploring; we would only get a counterexample if we were to disambiguate (a) and (b) in a uniform way. But no matter how we do this, the resulting sentences strike us as equivalent. (Khoo & Mandelkern (forthcoming), pp. 8 - 9 in online version).
In view of the fact that even the most suspect of Gibbard’s explicitly stated principles has proven difficult to reject, it is not surprising that some have rejected auxiliary assumptions not directly appealed to in the derivation. According to Kratzer (1986, 2012, p. 105 in latter) - whose syntactically distinctive theory of indicatives was inspired by Lewis (1975) - the problem with Gibbard’s argument is that it relies on the assumption that indicative conditionals are propositions formed by an operator, ‘if’, which takes two propositions and yields a proposition. If instead we follow Kratzer and treat ‘if’ as a restrictor, and regard ordinary indicative conditionals as containing an unvoiced necessity operator restricted by ‘if’, the conclusion of Gibbard’s argument no longer leads to the result that indicative conditionals, if they have truth-conditions at all, are truth-functional. For Gibbard’s conclusion is that if indicative conditionals are propositions in which a two-place propositional operator is applied to two propositions, then their truth-conditions collapse to those of the material conditional.
However, as Khoo (2013) has shown in detail, an analogous argument can be given directly in terms of the semantic values of sentence-schemas, without assuming that ‘if’ is a two-place propositional operator. But it turns out that Kratzer’s theory is nevertheless able, in another way, to block both the original and the analogous argument. Kratzer’s theory predicts subtle counterexamples to the principle that whenever an indicative conditional is true, so is the corresponding material conditional, thus invalidating the If Implies Hook assumption of Gibbard’s argument. So too does Gillies’ (2009) theory, on which ‘if’ is a two-place operator, but one which is able to shift the index and context[2] against which the consequent of an indicative conditional is evaluated (in the course of the evaluation of the conditional containing it).
On Khoo’s analysis, Kratzer’s alternative view of the syntax of indicative conditionals is orthogonal to the collapse issue. Both her theory, on which ‘if’ is a restrictor, and Gillies’ theory, on which ‘if’ is a “shifty” two-place propositional operator, avoid Gibbard’s conclusion. But in consequence of how they avoid Gibbard’s conclusion - by invalidating If Implies Hook - both theories predict counterexamples to modus ponens construed as a semantic thesis according to which ‘C’ is true whenever ‘A’ and ‘If A then C’ are both true.
Completely invalidating modus ponens would be a serious issue and would naturally cast doubt on these theories. But, like McGee’s (1985) independently-motivated counterexample to modus ponens, the main conditionals in the predicted counterexamples feature indicative conditionals in their consequents. That the predicted counterexamples are in this way similar to independently-motivated ones suggests that they are not mere artefacts of faulty theories. Furthermore, while modus ponens construed as a semantic thesis as explained above turns out to be invalid on these theories, modus ponens as a practical inference rule remains unaffected, insofar as asserting or supposing something has the effect of restricting the range of possibilities against which conditionals are evaluated to ones in which that thing holds. In this way, both theories are compatible with modus ponens being “dynamically valid” (for details see Khoo (2013)). It seems reasonable to suppose that this is all the modus ponens we need.
Although the whole of this intricate story could not have been imagined by Gibbard, he certainly was aware in the abstract that theories which, like Kratzer’s and Gillies’, allow embedded indicative conditionals’ semantic values to differ from the semantic values they would get if taken alone, have the resources to avoid his conclusion.
This possibility, now realised in detail by existing theories, was the very escape route that Gibbard identified and gave reason not to take. The assumption that a given indicative conditional sentence in a given context always gets the same semantic value, regardless of whether it is embedded in a larger conditional, is thus an auxiliary assumption of Gibbard’s proof.
3. Why Gibbard Wouldn’t Take the Escape Route
Gibbard’s identification of this auxiliary assumption and his argument against rejecting it are contained in the following passage:
One other possibility remains: that → always represents a propositional function, but that what that function is depends not only on the utterer's epistemic state, but on the place of the connective in the sentence. In a → (b → c), for instance, we might suppose that the two different arrows represent two different propositional functions. Nothing we have seen rules that out.
The pursuit of such a theory, though, has now lost its advantage. A theory of indicative conditionals as propositions was supposed to give, at no extra cost, a general theory of sentences with indicative conditional components: simply add the theory of conditionals to our extant theory of the ways truth-conditions of sentences depend on the truth-conditions of their components. The alternative was to develop a new theory to account for each way indicative conditionals might be embedded in longer sentences, and that seemed costly. Now it turns out that for each way indicative conditionals might be embedded in longer sentences, a propositional theory will have to account for their propositional content, and do so in a way that is sensitive to the place of each indicative conditional in its sentence. In a → (b → c), the right and left arrows must be treated separately. What must be done with the left and right arrow in (a → b) → c or with the arrows in a & (b → c) and a ∨ (b → c) we do not yet know. Thus, for instance, no account of sentences of the form (a → b) → c will fall out of a simple general account of indicative conditionals as propositions; rather the account of indicative conditionals itself will have to confront separately the way left-embedded arrows work. A propositional theory would not save labor; instead it would demand all the labor that would have to be done without it. (Gibbard (1981), pp. 236-237)
The way Gibbard puts it, the assumption at issue is that ‘→ is a fixed propositional function’ (Gibbard (1981, p. 236)), but for present purposes it is the ‘fixed’ part that is relevant, and in view of the possibility of a Kratzerian treatment of the syntax of indicatives, we should separate the ‘fixed’ part out and state it in a way that does not presuppose that ‘→’ is syntactically a two-place propositional operator. Hence our statement of it at the end of the previous section: a given indicative conditional sentence in a given context always gets the same semantic value, regardless of whether it is embedded in a larger conditional. Or in other words again, the assumption is that in a given context, there is no more than one indicative conditional with one set of truth-conditions per pair of antecedent and consequent. Henceforth let’s call this the fixity assumption.
4. The Escape Route is Open
I will give a four-pronged argument against Gibbard’s defense of the fixity assumption. If it is successful, we are left free to abandon the fixity assumption and thus to resist the collapse of indicative conditionals into material conditionals while maintaining a truth-conditional approach to indivatives.
Prong 1. Gibbard’s description of the extra work we must do if we abandon the fixity assumption in the pursuit of truth-conditions for indicatives overplays the amount of extra work required, due to what appears to be a (forgivable) failure of theoretical imagination on his part.
Gibbard says that if we give up fixity, then ‘for each way indicative conditionals might be embedded in longer sentences, a propositional theory will have to account for their propositional content, and do so in a way that is sensitive to the place of each indicative conditional in its sentence’. This may be strictly correct, but it doesn’t follow that such a theory has to confront each form of embedding separately, or that this sensitivity to place cannot come about in an elegant, systematic way.
Indeed, the sensitivity to place of indicatives-inside-indicatives that we need in order to block Gibbard’s collapse argument does come about in an elegant, systematic way on both of the theories we have been discussing. On Kratzer’s theory, it stems from the fact that ‘if’ restricts a modal and that such restriction may occur more than once in a single sentence. On Gillies’, it stems from the fact that ‘if’ shifts index and context, and that such shifting may occur multiple times in a single sentence.
Thus, when Gibbard says that ‘no account of sentences of the form (a → b) → c will fall out of a simple general account of indicative conditionals as propositions; rather the account of indicative conditionals itself will have to confront separately the way left-embedded arrows work’, this - provided that Kratzer’s and Gillies’ theories qualify as ‘simple’ - is simply false. An account of sentences of that form does fall out of both accounts.
Krazter’s and Gillies’ theories deliver, in an elegant way, different semantic values for conditionals depending on where they are in a sentence. And it seems to me that there is a good sense in which these theories are such that we can ‘simply add the theory of conditionals to our extant theory of the ways truth-conditions of sentences depend on the truth-conditions of their components’.
Prong 2. Following Gibbard in embracing the NTV thesis creates special work of its own, which does not have to be done if we hold that they have truth-values.
For one thing, there is an irony in his complaint that if we give up the fixity assumption ‘we do not know’ what to do with the arrow in a sentence of the form ‘a ∨ (b → c)’. In keeping with what we saw in the previous prong, the fixity-denying theories we now have do not encounter any special difficulty in handling such sentences, and we do not have to consider such forms of embedding on a one-by-one basis. Now we may observe further that, if anything, it is the NTV route that leads to issues with such a form; if we deny truth-values to indicative conditionals, we don’t know what to do with the wedge in such a sentence. That is, we face the extra work of making sense of, or denying sense to, embeddings of allegedly truth-valueless sentences in what appear to be truth-functional contexts. (See, however, Edgington (1995) for a classic defense of the view that such embeddings are not problematic after all.)
That is one sort of extra work the NTV theorist seems to be saddled with. And there is another, quite different sort. Namely, the work of explaining what is going on when people appear to ascribe truth-values to indicatives. A truth-value-granting view of indicatives such as Kratzer’s or Gillies’ lets us take these ascriptions at face value, and to allow that they are often correct. An NTV view must either reinterpret these ascriptions so that they aren’t all incorrect, or explain why people so often say these incorrect things. So if we want to avoid extra work, it may be that we do better to uphold truth-value-granting theories like Kratzer’s and Gillies’.
Prong 3. It’s not all about extra work! The issue is whether we should or should not respond to the collapse argument by denying that indicatives have truth-values. To proceed as though this issue turns just on whether we save labor by maintaining that indicatives have truth-values is too narrow. Labor-saving patently isn’t the only reason why we might want to maintain that indicatives have truth-values. A distinct and arguably very important reason is that they seem to have truth-values! (How compelling you find this will depend on your philosophical orientation, but if you think that what pre-theoretically seems to be the case is an important guide in philosophy, it should count for quite a bit.)
Prong 4. Gibbard’s argument against abandoning the fixity assumption obscures the fact that, when you think about it, it makes sense to expect the assumption to be false. Rejecting the assumption is presented by Gibbard as a last resort. But rejecting the fixity assumption is not, on reflection, some intuitively unpalatable thing which we get forced into doing just so that we can uphold a prejudice.
There are well-developed, intuitively motivated views which enable us to think of indicative conditionals, schematically, as saying something like ‘In all relevant possibilities in which the antecedent holds, the consequent holds’. And it is quite natural to think that what is known to be true, or what is being supposed to be true, can affect what possibilities are relevant. Furthermore, it is quite natural to think of the antecedents of conditionals, for example, as introducing a supposition. Putting these last two things together, it is quite natural to think that the possibilities relevant for the ‘if B then C’ in ‘If A, then if B then C’ may differ from the possibilities relevant for an unembedded ‘If B then C’. In particular, it is natural to think that only A-possibilities will be relevant to the embedded conditional, while not-A-possibilities may still be relevant to the unembedded one.
So, the negation of the fixity assumption is something which has quite a bit of plausibility. At the very least, it seems plausible from within the general way of looking at indicatives which the collapse argument is supposed to threaten. Namely, a perspective according to which indicatives have truth-values and in some sense deal with ranges of relevant possibilities. And obviously, such a perspective has much to recommend it besides helping us to resist Gibbard’s argument.
5. Conclusion
Starting from the intuitiveness of the view that indicative conditionals have truth-values which can differ from those of the corresponding material conditional, we looked at how Gibbard’s collapse argument threatens that view, and how Import-Export, flagged as suspicious by Fitelson, is hard to fault. Drawing on work by Khoo, we then saw that both Kratzer’s and Gillies’ independently-motivated theories of indicative conditionals block Gibbard’s argument at the cost of invalidating modus ponens construed as a general semantic thesis, but that the predicted counterexamples coincide with McGee’s independently-motivated ones and leave modus ponens unscathed as a form of dynamically valid inference. We then looked at Gibbard’s argument against truth-value-granting theories of indicatives which, like Kratzer’s and Gillies’, reject the fixity assumption, and saw that the threat is not serious. Gibbard’s refusal to abandon fixity in pursuit of truth-conditions for indicatives stemmed from a failure of theoretical imagination and a too-narrow view of the motivations for non-material, truth-value-granting accounts of indicatives. The prospects for such accounts appear to be brightening.
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[1] Gibbard leaves the notion of ‘logical truth’ unexplicated in his proof, but the arguments in the present article do not turn on any particular understanding of it.
[2] Contexts, whatever they are, should be thought of as determining ranges or sets of possibilities relevant to the evaluation of conditionals in that context. Cf. Gillies (2009), p. 329 (incl. f.n. 5). Note also that the use of ‘possibilities’ here should not be taken to imply that the possibilities in question are all metaphysical possibilities.