“Abilities” Updated

I recently made significant updates to my encyclopedia article on “Abilities” in the Stanford Encyclopedia of Philosophy. Changes include a more extensive review of modal theories of ability, discussion of important work on “two-way powers,” and a brief discussion of David Lewis’s theory of ability, initially outlined in 2000 year but published only recently.

The SEP is a dynamically updated resource so I would welcome any observations of typos, minor errors, etc. so that I can correct these. (More substantive criticisms are very much welcome too, though it may take me longer to address these).

‘Can’ and Reference

I would like to make an observation about the semantics of ‘can’ (and, I believe, of agentive modals generally) that has not been noted, to my knowledge, in the previous literature. This observation appears to tell against a theory of ‘can’ of the kind proposed by Kratzer in her great essays on this topic.

Quine says that a context is ‘referentially opaque’ just in case the substitution of co-referring names may induce a change in truth value. Thus:

(1) Lois is unaware that Clark was born on Krypton

(2) Lois is unaware that Superman was born on Krypton

We can imagine that (1) is true and (2) false (perhaps this was true in the comic books). So ‘is unaware that’ is referentially opaque.

By contrast, a context is ‘referentially transparent’ just in case the substitution of co-referring names does not induce a change in truth value.

It will be helpful to define up an additional notion. Let us say that a context is strongly referentially transparent just in case the substitution of co-referring names OR definite descriptions does not induce a change in truth value. (Maybe this notion already has a name in the previous literature, and I think some people may already be using transparency in this broader sense, or even more broadly to range over demonstratives etc. Anyhow, this is how I will be using the term).

I now wish to make two claims: (i) ‘can’ is strongly referentially transparent and (ii) this is difficult to accommodate within the standard Kratzer framework for ‘can’.

Here is the argument for (i). Let us say that Smith is in fact the most popular man in town. Consider:

(3) Jones can have dinner with Smith

(4) Jones can have dinner with the most popular man in town

Given that Smith is in fact the most popular man in town, the truth of (3) ensures the truth of (4), and conversely. There is no way for the one to be true and the other false.

Crucially, this is the case even under unusual circumstances. Let us say that Smith would in fact have dinner with Jones only if his popularity declined – since he is so popular, he is very busy, but were he less popular, his calendar would free up. So – now speaking a bit more semantically – the scenario in which Jones in fact has dinner with Smith is one in which Smith is _not_ the most popular man in town. Nonetheless, that scenario suffices for the truth of (4), since we describe the scenario in terms of how things actually are – and, actually, Smith is the most popular man in town. So we might sensibly say: “Jones can have dinner with the most popular man in town, Smith, though, if they really did have dinner, Smith would not be so popular.”

Here is the argument for (ii), that it is difficult to accommodate this observation within the Kratzer semantics. On the Kratzer semantics, (3) is true only if there is a world w meeting certain conditions (roughly, that it is in the set of worlds W that are compatible with the modal base and that are most highly-ranked according to the ordering source) such that Jones has dinner with Smith at that world. Let us say that there is some such world – call it w1 – and so that (3) is true.

Now, by our argument above, (4) must be true as well. Is it? Well, (4) is true only if there is a world w meeting certain conditions (roughly, that it is in the set of worlds W that are compatible with the modal base and that are most highly-ranked according to the ordering source) such that Jones has dinner with the most popular man in town at that world. Is there? Well, there may or may not be. Since all that is ensured by the truth of (3) is the existence and accessibility of w1, the truth of (4) is ensured only if w1 is a world such that Jones has dinner with the most popular man in town at that world. And this may not be the case, as in the scenario described above.

So it is difficult to explain the strong referential transparency of ‘can’ on the Kratzer account. I do not say that it is impossible to do so, and I’m open to the idea that some mechanism could give an explanation of this phenomenon. That said, I think this little argument suggests two broader points.

First, there’s an extensive philosophical literature on reference and modality, including the Quine essay mentioned above and a few lectures. To some extent these issues have been taken up in the excellent recent literature on epistemic modals. To my knowledge, they are less studied in the literature on ‘root modals,’ which include agentive modals but also include circumstantial modals more generally as well as deontic modals. I’d be interested in seeing more discussion of how issues of reference and modality play out in thinking about root modals.

Second, I’m sympathetic with the thought that agentive modals don’t quantify over worlds but instead quantify over intra-worldly entities – what I call options. Options are not themselves modal, though they do have modal entailments. On my view, (3) is true because Jones has, at this world, a certain option. That very option is, at this world, an option of meeting the most popular man in town. So (4) is true as well. So this is a phenomenon that can be explained quite simply when we take options as fundamental.

The Conditional Analysis

I have a small remark/complaint about the literature that came up in passing as I was refereeing a paper, not for the first time. I wasn’t sure how to get this out of my craw, so a blog post seemed appropriate.

Various authors, including myself, have inveighed against “the conditional analysis” of ability. Indeed some authors (mainly in the free will literature) taken it as given that this analysis is bankrupt. And yet. In the recent literature, there are several proposals that defend a sophisticated version of the conditional analysis. This recent, elegant, paper in the Philosophical Review is perhaps the best example. So a cursory reading of the literature might suggest that reports of the demise of the conditional analysis were premature.

In fact I think this is not so. There are at least two things that might be called the “conditional analysis”, or, better, there are two roles that conditionals might be thought to play in an account of ability and the ascription of ability. Once we distinguish these, the issues in the literature become much clearer.

First, the conditional analysis might be thought to give a reduction of agentive modality to some more general variety of modality, namely that involved in the subjunctive conditional. So it is proposed that: S is able to A <-> if S were to try to A, S would A. If a reductive semantics of the subjunctive conditional could be given – perhaps in terms of possible worlds a la Stalnaker and Lewis – we would then have gone some way towards the reduction of agentive modality to the amodal. In this sense the conditional analysis of ability is of a piece with the conditional analysis of dispositions, the best-systems account of laws of nature, and other redoubtable members of the Humean repertoire.

I think there’s a pretty good case that this reductive understanding of the conditional analysis is not going to work. (I give a few reasons here and elsewhere). But . . .

Second, the conditional analysis might be deployed to address a quite different issue. This is a problem not of reduction but of extension. Here’s the issue. The things that agents are able to do – what I call their options – are somewhat different from the complements in ability ascriptions. For instance, I might have truly said in 2007: “Obama is able to become President.” But Obama perhaps didn’t have that as an option. Maybe he had a bunch of smaller options – giving this speech, shaking that hand, etc. – that together would add up to his becoming President. And there is some plausibility to understanding that as follows: there was something/somethings Obama could do such that, if he did it/them, he would become President. That is in some sense an “analysis” of “Obama is able to become President,” and it is one that makes essential appeal to a conditional.

Now I’m not sure if that proposal is right, but it’s certainly worth considering as a treatment of the extension problem and it certainly is in some sense a “conditional analysis.” It’s the kind of proposal that’s advanced in the article mentioned above. But it’s important to distinguish it from the traditional conditional analysis. Crucially, a notion of agentive modality figures as a primitive in the account, whereas the whole point of the traditional conditional analysis was to analyze that away. This rather different kind of conditional analysis involves deploying the conditional in a much different, and more modest, way.

So: the conditional analysis, understood as a reductive account of agentive modality, did not work. But, once we admit some primitive agentive modality into our account, we may introduce subjunctive conditionals into our account to solve other problems, such as the extension problem sketched above.



The Open Seminars

One purpose of this blog is to serve as a home for my various side-projects, one of which (currently on hiatus) is the Open Seminars. Here’s some details about them:

In Summer 2018, I led an online seminar on Wittgenstein’s Tractatus Logico-Philosophicus. The course was free to any student, and consisted of a mix of lecture and live question-and-answer about the Tractatus. In addition to its philosophical content, the course was an experiment in teaching philosophy online in a cost-effective and open way. As such, it may be of interest to others. The entirety of the seminars are available here.