Tuesday, 26 January 2016

Indicative Modality is Not Epistemic

Philosophers today frequently identify indicative modality with apriority, or at least identify it as an epistemic notion.

For instance, the abstract for a recent talk by Greg Restall (currently available at his website) refers to 'subjunctive (metaphyisical) and indicative (epistemic) modalities'.

Even Chalmers in his admirable piece on the tyranny of the subjunctive, which might be expected to resist this tendency, bites the bullet here. Witness:

(4) SIX POSSIBLE REASONS FOR FAVORING THE SUBJUNCTIVE 
(a) Indicative necessity is "merely epistemic".
    [Answer: So? Before 1970, almost everyone thought necessity was tied to the epistemic (cf. Pap's book). Kripke *argued* that necessity and epistemic notions came apart, by appeal to the subjunctive, but one can't simply presuppose it.]

This is a mistake. Indicative modality is not epistemic. A proposition is subjunctively necessarily true when it could not have been false, no matter what. A proposition is indicatively necessarily true when it cannot be false, no matter what.

I see no reason to think we need to understand this latter notion by appealing to anything to do with knowledge or a knowing subject. The idea is rather that an indicatively necessary proposition is true by its very nature, or has truth as an internal property.

It may be that a proposition is a priori iff it is indicatively necessary (or maybe the two categories are almost but not completely aligned). I once proposed something like this as an analysis of the concept of apriority. While this may still be an instructive result, shedding light on apriority and indicative necessity both, I no longer think it should be thought of as giving the content or intension of the notion of apriority. That should be left as a concept which has to do with knowledge or knowability, and indicative necessity recognized as an interesting, and non-epistemic, concept in its own right.

This point is just a continuation of Kripke's work in distinguishing concepts of propositional typology which have typically been conflated.

Monday, 18 January 2016

Does Kripke Really Have Obstinate Rigidity in Mind at All in Naming and Necessity?

Philosophers, in the wake of Naming and Necessity, have distinguished the main Kripkean notion of rigid designation, which applies to an expression when it designates the same object in all possible worlds (or counterfactual situations) in which that object exists, from a putative notion called 'obstinate rigidity', which applies to an expression when it designated the same object in every possible world whatever, including worlds where that object doesn't exist. (The term 'obstinate rigidity' was introduced by Nathan Salmon on page 34 of his 1981 book, Reference and Essence.)

I'm not even sure I can make sense of the notion of obstinate rigidity. My main purpose here is not to discredit it, however, but to do something more modest: I want to suggest that a line of interpretation of Kripke, which has him sometimes working with a notion of obstinate rigidity instead of his normal official notion of rigidity, is mistaken.


From the Stanford Encyclopedia of Philosophy article 'Rigid Designators':

In other places, Kripke seems to have in mind another account of rigidity: one according to which a rigid designator designates its object in every possible world, whether or not the designatum exists in that world. Hence, he says, “If you say, ‘suppose Hitler had never been born’ then ‘Hitler’ refers here, still rigidly, to something that would not exist in the counterfactual situation described” (Kripke 1980, p. 78).
The interpretative suggestion before the quote seems wrong to me. I find it more natural to think that Kripke is saying that 'Hitler' actually refers, rigidly, to something that would not exist in another counterfactual situation - not that it refers to that thing in that situation.

Here we have to be careful to distinguish:


What does expression X refer to in counterfactual situation Y? (Which in turn must be carefully disambiguated, in a familiar Kripkean way, so that it does not get interpreted as asking about how language would be used in counterfactual situation Y.)


from


What does expression X actually refer to when it appears in this description of counterfactual situation Y?

You can answer 'Nothing' to the first and 'Hitler' to the second.

(Things may get even subtler when you consider definite descriptions. Suppose John is the tallest man in the world, but Paul might have been. Then if we say 'Paul might have been the tallest man in the world', should we still say that the actual referent of 'the tallest man in the world' in that sentence is John? To this, one wants to object that John isn't really involved. (But does that matter, when the question was about what the actual referent is?) Perhaps someone could find principled grounds for denying 'The actual referent of "the tallest man in the world" in that sentence is John' while accepting the 'Nothing'/'Hitler' pair of answers above. Perhaps Donnellan's distinction between referential and attributive uses of definite descriptions, or something like that distinction, should come into play here. Still, this complication - and it really is enough to do your head in - shouldn't impinge on the plausibility of what was said above.)

Saturday, 2 January 2016

The Humphrey Objection to Modal Realism

The Humphrey objection to modal realism, due to Kripke, centres on counterpart theory, and alleges that this assigns counterintuitive truth-conditions to modal statements about individuals. It is historically important, as Kripke made the objection in his influential Naming and Necessity lectures, long before Lewis published his full defence of modal realism in 1986.

Kripke put the objection as follows:

Thus if we say "Humphrey might have won the election (if only he had done such-and-such)”, we are not talking about something that might have happened to Humphrey but to someone else, a "counterpart". Probably, however, Humphrey could not care less whether someone else, no matter how much resembling him, would have been victorious in another possible world. Thus, Lewis's view seems to me even more bizarre than the usual notions of transworld identification that it replaces. (Kripke 1980:45 note 13.)

It is by now, I think, pretty widely accepted that Kripke, while he may have been on to something here, did not put the point optimally. To the objection put this way, there is a cogent response: it is not correct to say that, according to counterpart-theoretic modal realism, we 'are not talking about something that might have happened to Humphrey'. What counterpart-theoretic says is that talk about 'what might have happened to Humphrey' is to be analyzed in terms of what does happen to his counterparts in other worlds. So according to the counterpart-theoretic modal realist, when we say 'Humphrey might have won the election', we are indeed talking about what might have happened to Humphrey. Their characteristic claim is to add that this thing we're talking about is to be analyzed in terms of what happens to counterparts. (Lewis drives this point home in On the Plurality of Worlds.)

Similarly, the second part of Kripke's objection – that 'Humphrey could not care less whether someone else, no matter how much resembling him, would have been victorious in another possible world' – can be convincingly argued to miss the mark. The counterpart-theoretic modal realist can agree that Humphrey could not care less about this. For the way they analyze talk about whether 'someone else' (a counterpart) 'would have been victorious in another possible world' is in terms of counterparts of that someone else – counterparts of Humphrey's counterparts. And it is compatible with Humphrey not being interested in what happens to the counterparts of some one of his counterparts, that he be interested in something which – upon analysis – turns out to be a question of what happens to his own counterparts.

This last point may be a bit pedantic, however. What if we simply reform the second part of Kripke's objection by changing the 'would have been' to an 'is'? This yields: 'Humphrey could not care less whether someone else, no matter how much resembling him, is victorious in another possible world?'

This is better, but there is still a strong reply. As Sider says in his unpublished 'Beyond the Humphrey Objection', this is 'just the paradox of analysis':

A reasonable person can care about a property under one description (“possibly winning”) while not caring about the same property under another description (“having a counterpart who wins”), provided it is not obvious that the descriptions pick out the same property. Correct analyses need not be obvious to competent language users. Obviousness may count for something, but theoretical virtues are important as well in determining which analyses we ought to accept (p. 2)

I endorse this as a response to the version of the Humphrey objection just considered. However, I want presently to register a difference with Sider about whether this response also works for another version of the objection.

This other version puts aside what Humphrey cares about, and appeals directly to our intuitions. Sider puts this version of the objection as follows: 'Look, it is just obvious that possibly winning is not the same as having a counterpart who wins' (pp. 1 – 2) And the response quoted above is put forward by Sider as a response to both the previously considered version and this one. (He explicitly prefaces the passage with 'Reply to ii) and iii)' (p. 2).)

Does Sider's response apply here too? On reflection, I think clearly not. The response makes the point that a correct analysis need not be obvious (while granting that obviousness may count for something). But the present version of the objection is alleging, not that it isn't obvious, but that it is obviously not the case. Sider, in putting the passage in question forward as a response to this, is sliding from '(~p) is obvious' to '~(p is obvious)' and thus failing to address the objection.

So we seem to have a version of the Humphrey objection which is stronger than the others so far considered. But we can improve it further by getting away from obviousness altogether, which is a red herring. Saying that possibly winning is obviously not the same as having a winning counterpart risks being too strong. The rhetorically wise thing to do is tone it down, and simply enter a plea that it doesn't intuitively seem that possibly winning is the same as having a winning counterpart. Or putting the point semantically: the truth-condition Lewis assigns to 'Humphrey could have won' is counterintuitive.

So, despite the availability of strong responses to the original and certain subsequent versions of the Humphrey objection, the core point remains that the truth-condition assigned by Lewis is counterintuitive.

(Incidentally, Lewis suggested that forms of ersatzism are no better on this score: in that case, what “gets into the act” is not another person, but 'some abstract whatnot' (Lewis 1986, p. 194.) This isn't a strong reply to the objection, of course, as ersatzism is far from the only other game in town when it comes to the semantics of modal attributions such as 'Humphrey might have won'. Nevertheless and for what it's worth: perhaps an abstract whatnot getting into the act is, from an intuitive point of view, not quite as bad as another person getting into the act. Bringing in another person, it seems to me, feels more like crowding out Humphrey, more like putting something in his place.)

So, there is a version of the Humphrey objection which has some force. However, modal realism with overlap, in contrast to counterpart-theoretic modal realism a la Lewis, is immune to the Humphrey objection. Lewis wasn't swayed by this, since he had reasons to think modal realism with overlap unpalatable. Since then, advocates of overlap have, as might have been predicted, emerged (most notably McDaniel in his (2004), 'Modal Realism with Overlap').

It may be that the considerations against overlap are quite compelling, in which case these together with the Humphrey objection (once it is freed from its initial faulty formulation) have significant force against modal realism in general. However, I do not want to get deep into comparing the relative merits of counterpart-theoretic modal realism and modal realism with overlap, and would prefer to have an objection along similar lines which applies to both. Therefore, I advocate that we take the Humphrey objection, not just as a self-sufficient objection which affects the dominant form of modal realism but not modal realism with overlap, but also as a clue: modal realism – in both flavours – may be counterintuitive on the semantic front, and this may be a good reason to reject it. Since the Humphrey objection itself fails to apply to modal realism with overlap, we should set it aside and go on to try for a more general semantic objection. I hope to develop this in a future post.

References

Kripke, Saul A. (1980). Naming and Necessity. Harvard University Press.

Lewis, David K. (1986). On the Plurality of Worlds. Blackwell Publishers.

McDaniel, Kris (2004). Modal realism with overlap. Australasian Journal of Philosophy 82 (1):137 – 152.

Sider, Theodore. unpublished. Beyond the Humphrey Objection.

Friday, 25 December 2015

Quine's Poor Tom Revisited: Against Sayward

I have recently come back to the argument in section 31 of Quine's Word and Object. In a post just over four years ago I criticized the argument for a use-mention shift with regard to a principle which, on an opaque reading of 'believes', is a reasonable thing to require of a good logician, but which, on a transparent reading of 'believes', is not a reasonable thing to require of a good logician.

In Quine's argument as he stated it, the principle is introduced in terms of belief in sentences, which all but forces an opaque reading. But then when it is applied in the argument, Quine has semantically descended to a 'believes that' construction, and applies the principle in such a way as would only be legitimate if it is given the transparent reading.

The principle as originally stated runs as follows:
(Acumen) [P]oor Tom, whatever his limitations regarding Latin literature and local philanthropies, is enough of a logician to believe a sentence of the form ‘δp = 1’ when and only when he believes the sentence represented by ‘p’. (Quine 1960, p. 148.)
In that-clause form it runs as follows:
(AmbigThatAcumen) Tom believes that δp = 1 when and only when Tom believes that p
(For the definition of the 'δp = 1' construction see my original post, but it can be read as 'The truth-value of "p" = 1' without going far wrong.)

Sleigh's (1966) objection makes the same point that I made towards the end of my original post, namely that the (AmbigThatAcumen) is only a reasonable assumption on an opaque reading, whereas its transparent reading is needed for the argument. He did not note that Quine's originally stating the principle in terms of belief in sentences all but forces us to give it an opaque reading at that point in the argument.

Widerker (1977) and Sayward (2007) criticized Sleigh's objection. I did not engage with these papers in my original post. In this post, I would like to refute Sayward's criticism. I think this can be done more or less conclusively.

Widerker's objection is less easily dealt with, and leads us into some interesting territory. I am currently working on a paper where I try to sort out the whole mess, and try to draw a metaphilosophical lesson.

One of the most important things I did not appreciate earlier is that Quine in his argument does give us what is needed for a good argument for his ultimate conclusion, namely that it will not do to treat belief transparently always. Once we see this, what is so objectionable about his argument may start to look more like a matter of presentation.

The way Quine presents things, I would like to say, is not perspicuous, and cultivates an air of paradox. (Quine makes it look like he has shown that if we treat belief transparently always, and if Tom has good logical acumen and believes one true thing and one false thing, then he believes everything.) I think this is philosophically bad, and so presumably did Sleigh. But it is interesting to note that what originally looked more like a dry, logical error (so to speak) may be more effectively criticized in this way - as a matter of non-perspicuous, philosophically bad presentation, rather than the commission of a definite logical error which flouts a principle we could get the supporter of Quine's argument to agree to. (Compare on the one hand the attempts of "cranks" to show that Cantor's diagonal proof was unsound, and on the other hand Wittgenstein's more sophisticated criticisms. I have blogged about this matter elsewhere.)

Sayward's criticism is simply that Sleigh has left it unargued that (AmbigThatAcumen) on its transparent reading is an unreasonable thing to require of  a logician - put differently, the criticism is that Sleigh has left it unargued that (AmbigThatAcumen) on its transparent reading does not express a form of logical acumen. He writes:
So if Sleigh’s point is to carry much weight it must take the form of a claim that no logical acumen, or at least none at all widely shared, is expressed by [(AmbigThatAcumen) read transparently]. But so far as I can see that simply goes unargued in his paper. Indeed, so far as I can see the paper contains no argument that the logical acumen to which Quine referred is not expressed by [(AmbigThatAcumen) read transparently]. It is simply and baldly asserted. (Sayward (2007), pp. 57 – 58.)
This objection can be convincingly rebutted. Firstly, it gets the dialectic wrong. Quine, for his argument to be plausible, needs his hypothesis about Tom's logical acumen plausibly to be about some genuine kind of logical acumen. I think it is perfectly fair to point out that this only seems to be so if we take the hypothesis opaquely, in which case it doesn't support the argument. This is already a good objection, in my judgement, without any further argument that it is not the case that (AmbigThatAcumen) read transparently – contrary to appearance – does express logical acumen after all.

Admittedly, this appearance may not be universal. This leads us to a second, stronger, point against Sayward's objection: Sleigh does give an argument that no logical acumen is expressed by the transparent reading! Sayward's claim that he does not do so is a sheer mistake. The argument comes at the end of Sleigh's note and runs as follows (except I have, for ease of reading, removed the subscript notation which he applies to singular terms to disambiguate between transparent and opaque, and simply put bracketed specifications of the intended reading next to 'believes' instead):
Obviously, (4') does not express the idea of Tom's acumen. Consider: 
(9) Tom believes [transparent] that [δp] = 1. 
and 
(10) Tom believes [opaque] that [2­ - 1] = 1. 
Given (10), (9) is true provided the sentence represented by 'p' is true. But we cannot infer from this that Tom believes the sentence represented by 'p' even if every singular term in 'pis taken transparently and even if Tom is overflowing with logical acumen. (Sleigh 1966, p. 93.)
Clearly this is an argument, so Sayward is just wrong in saying that Sleigh doesn't offer one. I think it's a perfectly good argument, too – although I think it was unnecessary to make 'believes' in (10) opaque and (as I hope to make clear in the paper I am working on and perhaps a future post here) this makes Sleigh more vulnerable to Widerker's criticism.

Finally, I think we can give a more straightforward argument that the transparent reading does not express any sort of logical acumen. To rewrite the principle with an explicit disambiguation:
(TransparentThatAcumen) Tom believes [transparent] that δp = 1 when and only when he believes [transparent] that p.
Now, let us plug in some truth for 'p' which not everyone with logical acumen knows – say, 'Quine was born in 1908':
Tom believes [transparent] that δ(Quine was born in 1908) = 1 when and only when he believes [transparent] that Quine was born in 1908.
Now, substituting '1' for the co­extensive 'δ(Quine was born in 1908)', we get
Tom believes [transparent] that 1 = 1 when and only when he believes [transparent] that Quine was born in 1908.
This is plainly not something we should require of a reasoner. Using 'of' language to induce a transparent reading, so that the point reads more intuitively: a reasoner may not believe, of Quine, that he was born in 1908. They may not have any beliefs about Quine at all. Obviously, they should not in that case – by the 'only when', which is essential to Quine's argument – fail to believe, of 1, that it is equal to 1. But we obtained this wrong result just by substituting co-extensive terms in an instance of (TransparentThatAcumen). Therefore (TransparentThatAcumen) does not express any sort of logical acumen. Rather, it seems like something we definitely shouldn't conform to.

The above, I think, completely diffuses Sayward's criticism.

References
- Quine, W. V. (1960). Word and Object. The MIT Press.
- Charles Sayward (2007). Quine and his Critics on Truth-Functionality and Extensionality. Logic and Logical Philosophy 16:45-63.
- R. C. Sleigh (1966). A note on an argument of Quine's. Philosophical Studies 17 (6):91 - 93.
- David Widerker (1977). Epistemic opacity again. Philosophical Studies 32 (4):355 - 358. 

Monday, 21 December 2015

Modal Realism

This is just an expository post, but I hope to make some original points in subsequent posts which will consider objections to modal realism.

Central to modal realism are the Liebnizian biconditionals,

(Lieb­NEC) A proposition is necessary iff it is true in all possible worlds.
(Lieb­POSS) A proposition is possible iff it is true at some possible world.

These tie attributions of necessity and possibility to quantificational statements about possible worlds. Different philosophical accounts which use these sentences accounts differ over what sorts of things possible worlds are taken to be, and over the role given to the Liebnizian biconditionals. (With typical forms of modal fictionalism, the biconditionals are typically augmented with an 'According to F' operator, where 'F' names a fiction.) The distinctive marks of modal realism, setting it apart from other philosophical uses of the Liebnizian biconditionals, are that it takes possible worlds to be of the same kind as the actual, concrete world we live in, that it takes the Liebnizian biconditionals to be true all by themselves (no fiction operator required), and that it takes these to constitute analyses of the modal notions appearing on the left hand sides.

The chief proponent and developer of modal realism, David Lewis, intends it to be a reductive account of modality – so his theory of possible worlds must be spelled out non­modally. Accordingly, the 'possible' in 'possible world(s)' on the right hand sides of the biconditionals is not supposed to be taken as anything more than part of a conventional, historically familiar way of referring to the worlds which do the work in his account. 

Such is the theory of modal realism in broad outline. Its characteristic commitments may be summed up in one sentence as 'There are other worlds, and every way our world might have been is a way some world is' (cf. Lewis 1986, p. 2).

In future posts I want to consider some objections to modal realism, but first let us consider in a preliminary way three finer points about the theory.

One finer point concerns the individuation of worlds. As Lewis phrases the question, 'What makes  two things worldmates? How are the worlds demarcated one from another? Why don't all the possibilia comprise one big world? Or, at the other extreme, why isn't each possible neutrino a little world of its own?' (Lewis 1986, p.70). Lewis's answer to this is: spatiotemporal relatedness. '[W]henever two possible individuals are spatiotemporally related, they are worldmates. If there is any distance between them – be it great or small, spatial or temporal – they are parts of one single world.' (This gives rise to an objection – the island universes objection – based on the idea that we should not in our analysis of modality rule out the possibility of a world with multiple spatiotemporally unrelated “universes”. I will not consider this objection at length, but cf. Lewis 1986, p. 71, Bricker 2001 and Vacek 2013.)

The second finer point concerns the treatment of propositions about particular individuals, and how they are to be evaluated with respect to worlds other than our own (or more generally, worlds other than the one from which the propositions in question are being evaluated). To begin with, note that general statements pose no corresponding difficulty. Going along with the modal realist's doctrine that there are other worlds, a question like 'Is “All swans are white” true at all worlds?' seems to have a straightforward meaning (at least given the familiar point that we want to hold fixed the meaning of the sentence in question when evaluating the proposition with respect to other worlds). But if we ask 'Is “John is white” true at all worlds?', where John is some actual swan, the question arises: does John himself exist at any of the other worlds?

The two different answers we might give to this question correspond to different forms of modal realism. If we answer in the affirmative, we get what is called modal realism with overlap. If we answer in the negative, get what is called modal realism without overlap. The canonical form of modal realism, David Lewis's as developed in his (1986), is of the latter sort. In order to enable us to evaluate propositions about particular individuals with respect to other worlds in the framework of modal realism without overlap, Lewis developed a theory of counterparts. To evaluate 'John is white' at some world W, we as it were look at that world and select the closest counterpart to our this-­worldly swan John, and then consider whether that swan is white. If so, we say that 'John is white' is true at W. This approach has been felt to be damagingly counterintuitive, giving rise to an objection originated by Saul Kripke called the Humphrey objection, which we will consider in a futute post.

The third and final finer point I want to note concerns the issue of what, if anything, modal realism has to say about the extent or range of the worlds – what worlds are there, and what are they like? As Lewis saw the matter, it was incumbent on him to provide principles which so to speak “generate” sufficient worlds, so that there is one for every possibility. To this end he proposed a principle of recombination, but he admitted that this was inadequate (Lewis 1986, p. 92). More recently, it has been questioned whether any such principles are needed for the theory qua analysis of modality (cf. Cameron 2012).

Note that modal realism is obviously free of the chief defects of pre-Kripkean analyticity approaches – the modal realist analysis does not push us toward the conclusions, implausible ever since Kripke, that necessary truths are true in virtue of meaning, or that they are all a priori. This is one of the things which, together with the boldness and clearness (at least in a certain sense) of the theory, makes it such a serious contender given the present state of play.

In future posts I will consider objections to modal realism, some of which we have just alluded to. My ultimate conclusion will be that the most serious objections are very serious indeed, and devastating when taken together. (General methodological qualms about certainty in philosophy aside, I believe that the theory is certainly incorrect. But it is profoundly incorrect and cannot be discussed too carefully. This series of posts will necessarily fall short of plumbing the full depths of the matter.)

References

Bricker, Phillip (2001). Island Universes and the Analysis of Modality. In G. Preyer & F. Siebelt (eds.), Reality and Humean Supervenience: Essays on the Philosophy of David Lewis. Rowman and Littlefield

Cameron, Ross P. (2012). Why Lewis's analysis of modality succeeds in its reductive ambitions. Philosophers' Imprint 12 (8).

Lewis, David K. (1986). On the Plurality of Worlds. Blackwell Publishers.

Vacek, M. (2013). Modal Realism and Philosophical Analysis: The Case of Island Universes FILOZOFIA 68, No 10, p. 868-876.

Friday, 20 November 2015

Skepticism About Metaphysical Modality and Unclear Cases

Some philosophers are skeptical of the notion of metaphysical or subjunctive modality isolated by Kripke. They may think for instance that the notion of necessity de dicto is coherent but nothing falls under it, or they may think that isn't even a coherent or legitimate notion. This post is more about the latter.

One cause of such skepticism, I suspect, is that some of the canonical cases Kripke adduces in Naming and Necessity are not particularly clear cases. That is, they are borderline or disputable cases. In addition, the attitude Kripke seems to take to these cases may not be completely appropriate. With these cases, he sometimes gives the impression that the way to know how it is with them is to use intuition - and here the intuiting has a different character than in clear cases. It seems like a kind of hearkening or special receptivity is supposed to be needed. All this may seem, so to speak, occult. And if this doesn't put us off the notion altogether, it may yet mislead us about what sort of account we should look to give of it.

The sorts of cases I have in mind are those of the table - could it have been made of ice? (Kripke intuits that it couldn't.) And the Queen: could she have been born of different parents? (Kripke intuits that she couldn't.) 

(One thing about the Queen case which has troubled me for years is what I call the fish argument. This argument works by iterating the supposed necessity of origin; if the Queen is necessarily the child of her actual parents, and they are necessarily the children of their parents, then we seem to be forced to conclude that the Queen is necessarily the descendant of some fish which she is in fact descended from - call him Colin. That is, there is no possible world involving the Queen where Colin isn't also around. This seems dubious.)

To all this, my suggestion is that we shouldn't get hung up on such cases when it comes to the question of whether the notions of metaphysical or subjunctive modality are legitimate, and when it comes to understanding those notions. Just as, when trying to give someone a grasp of the notion of tallness, it is better to work with examples of people who are definitely tall, or definitely not tall. To start insisting on certain judgements about more borderline cases is not to the point, and may make the whole business seem dubious. I think that following my suggestion may help us both explain and legitimate the notions in question, and may help us account for them in the proper way.

Sunday, 1 November 2015

What is Necessity De Dicto?

I recently posted an account of necessity de dicto. The purpose of this post is to pin down exactly what this topic is. The notion in question of course looms large in contemporary analytic philosophy, but it will serve us well and keep us grounded to furnish in as clear a way as possible a basic characterization of it. In a future post, I will turn to specifying the problem or task which my account is addressed to with respect to the topic. In another future post, I will state some of my assumptions and guiding ideas.

The key source for the notion of necessity de dicto is of course Kripke's Naming and Necessity. It was there that our topic was (to the best of my knowledge) first clearly isolated and characterized. Priority aside, Kripke's characterization is not easily improved upon and has been very influential. (Regarding the notion itself, not its characterization: it is a very interesting historical question to what extent this notion was present in earlier thinking. Or to what extent similar notions were, and how they may relate to the present notion. I will make no attempt here to answer this.)

Kripke's starting-point in characterizing the notion of necessity de dicto is to remark that, while many (at the time he was speaking) seem not to differentiate between a priority and necessity, he certainly will not use 'a priori' and 'necessary' in the same way (p. 34). He then, after emphasizing that the notion of a priority is an epistemological one and mentioning some issues which might arise with that notion, gives the following characterisation of necessity:

The second concept which is in question is that of necessity. Sometimes this is used in an epistemological way and might then just mean a priori. And of course, sometimes it is used in a physical way when people distinguish between physical and logical necessity. But what I am concerned with here is a notion which is not a notion of epistemology but of metaphysics in some (I hope) nonpejorative sense. We ask whether something might have been true, or might have been false. Well, if something is false, it's obviously not necessarily true. If it is true, might it have been otherwise? Is it possible that, in this respect, the world should have been different from the way it is? If the answer is 'no', then this fact about the world is a necessary one. If the answer is 'yes', then this fact about the world is a contingent one. (pp. 35 – 36.)

This should go a long way to giving us an acceptable grasp of the notion of necessity de dicto. Kripke also says some things about the extension of the notion which may be of further help to this end. Before proceeding to that, however, I want to tighten up Kripke's characterization in a couple of ways, as well as emphasizing and de-emphasizing certain parts of it.

For one thing, note that Kripke moves freely here between talking of 'facts about the world' as well as things which can be called true or false, as the bearers of necessity. Later, he speaks also of 'states of affairs' and 'statements'. This is fine, but I want to make it clear that the topic I am addressing in my account is the notion of necessity as it applies to things which can be called true or false: statements – or as I say, propositions. This is what I mean by 'de dicto' in 'necessity de dicto'. To be still more precise about what propositions are – for a start, whether they are or involve sentences themselves, or just their meanings – is not necessary, but see this post for an approach I favour.

(At this point I should emphasize that that is all I mean by 'de dicto' in 'necessity de dicto'. The term 'de dicto', and the contrasting term 'de re', are used in various ways in philosophy. It it especially important to realize that I count all attributions of necessity to propositions as attributions of necessity de dicto, even when those propositions are “singular propositions” about individuals – i.e., propositions attributions of necessity to which David Lewis would deploy counterpart theory to understand.)

Something I want to emphasize in Kripke's characterization is the way it cashes out necessity in terms of counterfactual scenarios – to use the language of some two-dimensional semanticists, scenarios considered as counterfactual, rather than scenarios considered as actual. This could be emphasized by calling our topic 'counterfactual necessity de dicto' or 'subjunctive necessity dicto', but I avoid this for the sake of brevity.

(You may think that this is the same as the point that necessity is not to be understood epistemologically, but I'm not so sure. For one thing, I suspect there are notions of 'could actually be the case' and 'must actually be the case' which, even if 'a priori possible' and 'a priori true' may be good expressions for them, can be cashed out non-epistemologically. (Cf. this post.) For another thing, 'Could have been' talk can also be given an epistemological reading, along the lines of 'Was epistemically possible'. In any case, emphasizing that with the notion of necessity de dicto we are dealing with scenarios considered as counterfactual, can only help to avoid misunderstanding here.)

Something I want de-emphasize in Kripke's characterization, on the other hand, is the way he classifies the notion of necessity he wants to talk about as a notion belonging to metaphysics. I do not think this is essential to grasping the notion in question: that can be done without any recourse to a notion of metaphysics. Kripke's use of a category of metaphysics here may be slightly helpful in emphasizing that necessity de dicto is not an epistemological notion, but that point can be emphasized without a notion of metaphysics. Since we can easily get by here without invoking a notion of metaphysics, I think we ought to avoid doing so. I am not going to argue the point at length here, but I suspect that invoking a notion of metaphysics may lead to some unhelpful prejudice about how the notion is best to be understood and analyzed (if it is to be analyzed) – or more to the point, how it is not to be analyzed. In particular, I worry that it may cause prejudice against accounts which crucially involve semantic considerations, by promoting a vague idea that necessity de dicto is “all about” how things are in the world, as opposed to having anything to do with language and thought.

Finally, Kripke's characterization should be supplemented with something about the sense of 'necessary' being unrestricted or very broad. To see this, consider an utterance like 'It is true that I stayed home yesterday. This couldn't have been otherwise, as I had to be there to let the electrician in.' This utterance may be true, but in that case the 'couldn't have been otherwise' part is not about necessity de dicto in the sense I am interested in – we are dealing with a contextually restricted range of ways things could have been. For instance, we are probably ignoring ways things could have been in which I stop caring about having electricity, or in which I never made the appointment with the electrician, or in which the appointment was on a different day. This supplementation of the Kripkean characterization has become customary. Witness Timothy Williamson in an interview:

Something is metaphysically necessary if it couldn’t have been otherwise, in the most unrestricted sense. (Williamson & Antonsen 2010, p. 18.)

Or Daniel Stoljar, referring to:

(…) the completely unrestricted sense of possibility that philosophers sometimes call “logical” or “metaphysical” possibility (…) (Stoljar 2006, p. 34.)

Or this terminological stipulation made by van Invagen:

Modal terms will be used in their “metaphysical” or “unrestricted” sense (…). (van Invagen 2015, p. 35.)

There is a wrinkle here, however. For some things philosophers say may seem to go against the propriety of characterizing our topic in this way. On the way of speaking I have in mind, there are necessities in the sense of our topic which are not necessary in some other sense – 'logically' or 'mathematically' or 'epistemically' for example. See, for instance, this passage in Nathan Salmon (where he is arguing that an objection made to something he has proposed – the details of which don't matter here – does not hold water):
Metaphysical modality is definitely not an unrestricted limiting case. There are more modalities in Plato’s heaven than are dreamt of in my critics’ philosophy, and some of these are even less restrictive than metaphysical modality. One less restrictive type of modality is provided by mathematical necessity and mathematical possibility. […] Another type of modality less restrictive than metaphysical modality is provided by what is sometimes called ‘logical necessity’ and ‘logical possibility,’ to be distinguished from genuinely metaphysical necessity and possibility, or necessity and possibility tout court. A proposition is logically necessary if its truth is required on logical grounds alone […]. Although there is a way things logically could be according to which I am a credit card account, there is no way things metaphysically might have been according to which I am a credit card account. (Salmon 2005, p. 136)
But notice the contrast at the end of this passage between 'could be' and 'might have been'. Salmon is concerned here with what he calls 'the confusion between the generic notion of a way for things to be and the modal notion of a way things might have been'. According to Salmon, this confusion
is very probably the primary source of the idea that metaphysical modality is the limiting case of restricted modalities, that metaphysical necessity and possibility is the unrestricted, and hence the least restricted, type of necessity and possibility. For metaphysical necessity is indeed truth in all ways things might have been (modal, not generic), and metaphysical possibility is indeed truth in at least one way things might have been (modal, not generic). (ibid, p. 136.)
So, since we are explicitly talking about ways things might have been, it seems that Salmon would have no real disagreement after all with Williamson's succinct characterization of our topic, quoted above (except perhaps for some pragmatic disagreement about what to emphasize, or how best to use language to avoid potential confusions).

In any case, one thing that should be clear is that we are not dealing with a notion where certain contextually relevant matters of fact may be held fixed, as in the electrician example above.

So much for the intensional characterization of the notion of necessity de dicto. Another thing which may help us grasp the notion is consideration of its extension – cases, and what types of cases there are. Most instructive in this way are cases lying outside the overlap of necessity and a priority. After giving his intensional characterization of the notion, Kripke goes on to say that he will be arguing that, in addition to being conceptually different, the categories of necessity and a priority are extensionally different: 'I will argue below that in fact they are not even coextensive—that necessary a posteriori truths, and probably contingent a priori truths, both exist.' (Kripke 1980, p.38.)

An aspect of the character of the notion of necessity de dicto is captured vividly in some of Kripke's intuitive appeals regarding the necessary a posteriori, in particular with the use of the phrase 'given that', and similar language. For instance, if I think some object I have encountered empirically, a, is the same object as I have encountered empirically in other situations, b, then – while I might conceivably turn out to be wrong, i.e. while it might turn out to be the case that a is distinct from bgiven that a is indeed b, then a couldn't have been distinct from b; 'a = b' is necessary.

Regarding the contingent a priori, perhaps the most straightforward and instructive type of case occurs when a name is stipulated to refer to whatever object satisfies some description, where the description is of a sort where an object satisfying it could have failed to satisfy it. So if I stipulate that 'a' is to refer to the inventor of the zip (if there was an inventor of the zip), then the proposition 'a, if there is an a, invented the zip' is a priori: in virtue of the way I have set 'a' up to work, it just can't turn out empirically that a exists and yet didn't invent the zip after all. Now suppose that there is an inventor of the zip. In that case, the proposition 'a, if there is an a, invented the zip', while a priori, is contingent: someone else could have invented the zip.

We have now characterized our topic, first intensionally, by taking and modifying slightly Kripke's famous characterization, and then extensionally, by pointing to two striking types of cases. The next question we must address is 'What is the problem or task in relation to the topic, to which your account is a response?' I will concentrate on this in a future post.  

References

Kripke, Saul A. (1980). Naming and Necessity. Harvard University Press. (First published 1971.)

Williamson, Timothy & Antonsen, Paal (2010). Modality & Other Matters: An Interview with Timothy Williamson. Perspectives: International Postgraduate Journal of Philosophy 3 (1):16-29.

Salmon, Nathan U. (2005). 'The Logic of What Might Have Been' in Metaphysics, Mathematics, and Meaning. Oxford University Press. Article originally published in 1989.

Stoljar, Daniel (2006). Ignorance and Imagination: The Epistemic Origin of the Problem of Consciousness. Oxford: Oxford University Press.

van Invagen, Peter (2015). 'Nothing is Impossible' in God, Truth, and other Enigmas, Szatkowski, Miroslaw (ed.),. De Gruyter.