The latest issue of The Monist contains an outline of an unpublished paper by Lewis: "Nihil Obstat: An Analysis of Ability", along with a useful commentary by Helen Beebee, Maria Svedberg, and Ann Whittle.
Lewis's analysis of ability goes as follows:
You're able to φ iff, for some basic action
(1) doing it would be φing, and
(2) there is no obstacle to doing it.
It is clear from this analysis, and from the context in which it is presented, that Lewis is only interested in a rather specific sense of 'ability'. He wants to spell out the sense in which we are able to perform particular intentional actions that we don't actually perform, even if the world is deterministic. He is not interested in our ability to regrow injured skin, or in the ability of tardigrades and steel to withstand high temperatures. He also isn't interested in what are sometimes called "general abilities", like my ability to play the piano that I have even when I don't have access to a piano. (At any rate, this kind of ability is not covered by his analysis, and it isn't relevant to compatibilism.)
In the previous post, I have assumed that conversational context somehow determines a unique "suitable role" for each individual under discussion, relative to every epistemic subject. This is an unrealistic assumption.
For example, I believe that Canberra gets cold in winter. But Canberra is known to me as the occupant of many roles. Among other things, I know it as the capital of Australia, as the city in which I lived for most of 2012, and as the destination of my most recent international trip. When I say that I know (or believe) that Canberra gets cold, none of these roles may be particularly salient.
In this post, I'm going to present a first stab of a formal semantics for de re belief reports.
As I explained in the last post, I'm going to assume that for every epistemic subject at every time there is a set of doxastically accessible worlds, representing how the subject takes the world to be. I will sometimes refer to these worlds as the subject's 'belief worlds'.
On that background, we can make the guiding idea behind the Quine-Kaplan model more precise: 'S believes that x is F' is true iff there is a suitable role R such that (1) in all worlds doxastically accessible for S, whatever plays R is F, and (2) in the actual world, x plays R.
This is part 3 of a series on epistemic counterpart semantics (part 1, part 2).
Recall the guiding idea: A de re report 'S believes that x is F' is true iff there is a suitable role R such that (1) S believes that whatever plays R is F, and (2) in fact, x plays R.
I said that these truth-conditions naturally emerge if we treat 'believes' as a modal, quantifying over a set of accessible worlds. So I am going to assume that for any relevant subject in any relevant situation there is a set of "doxastically accessible" worlds which somehow characterise what the subject believes. I want to say a few words to clarify this assumption.
This is part 2 of a series on epistemic counterpart semantics. Part 1 is here.
I want to defend what I called the "Quine-Kaplan model" of de re belief ascriptions. According to this model, 'S believes that x is F' is true iff there is a suitable role R such that (1) S believes that whatever plays R is F, and (2) in fact, x plays R.
In this post, I mainly want to explain what I mean by a "suitable role". This will also bring to light some arguments in favour of the Quine-Kaplan model.
Let's start with a bit of history.
I have decided to write a series of posts on epistemic applications of counterpart semantics, mostly to organise my own thoughts.
Let's start with a motivating example, from Sæbø 2015.
On September 14 2006, Mary Beth Harshbarger shot her husband, whom she had mistaken for a bear. At the trial, she "steadily maintained that she thought her husband was a black bear", as you can read on Wikipedia.
We're interested in this sentence: "Mary thought her husband was a bear."
I drafted some blog posts on the pandemic over the last few months, but never got around to publish them. By now, almost everything I would want to say has been said better by others. Nonetheless, a few personal observations.
One thing that still puzzles me is why so few people saw this coming. When I read about the outbreak in Wuhan in late January, I bought hand santiser, toilet paper, and a short position on the German DAX index. Meanwhile, in the media, in governments, and in the stock market, the consensus seemed to be that there is no reason for concern or action. Not that I expected much from Donald Trump. But why didn't mainstream, sensible news sites raise the alarm? Why were almost all European governments so slow to react? Why did the stock market keep climbing almost all through February? Wasn't the risk plain to see?
Many sentences can be evaluated as true or false relative to a (possible) context. For example, 'it is raining' is true (in English) at all and only those possible contexts at which it is raining.
This relation between sentences (of a language) and contexts is arguably central to a theory of communication. At a first pass, what is communicated by an utterance of 'it is raining' is that the utterance context is among those at which the uttered sentence is true. (You can understand what is communicated without knowing where the utterance takes place.)
Truth-at-a-context is also arguably central to a theory of validity, entailment, and other logical concepts. At a first pass, 'it is raining' entails 'it is raining or snowing' because the latter is true in every possible context in which the former is true.
Another paper: "Discourse, Diversity, and Free Choice" has come out at the AJP.
This paper began as a couple of blog posts in January 2007, here and here. At the time, I was thinking about why counterfactuals with unspecific antecedents appear to imply counterfactuals with more specific antecedents. I noticed that a similar puzzle arises for possibility modals in general. My hunch was that this is a special kind of scalar implicature: if you say of a group of things (say, rooms) that they satisfy an unspecific predicate (like, having a size between 10 and 20 sqm), you implicate that different, more specific predicates, apply to different memebers of the group.
My paper "Ability and Possibility" has been published in Philosophers' Imprint. Here's the abstract:
According to the classical quantificational analysis of modals, an agent has the ability to perform an act iff (roughly) relevant facts about the agent and her environment are compatible with her performing the act. The analysis faces a number of problems, many of which can be traced to the fact that it takes even accidental performance of an act as proof of the relevant ability. I argue that ability statements are systematically ambiguous: on one reading, accidental performance really is enough; on another, more is required. The stronger notion of ability plays a central role in normative contexts. Both readings, I argue, can be captured within the classical quantificational framework, provided we allow conversational context to impose restrictions not just on the "accessible worlds" (the facts that are held fixed), but also on what counts as a performance of the relevant act among these worlds.