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.

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.)

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.