Posts on: Ability
Some ability statements sound wrong when affirmed but also when denied. Santorio (2024) proposes a new semantics that's built around this observation.
Suppose Ava is a mediocre dart player, and it's her turn. In this context, people often reject (1):
(1)Ava is able to hit the bullseye [on her next throw].
It's obviously possible that Ava gets lucky and hits the bullseye. But ability seems to require more than mere possibility of success. A common idea, which Santorio endorses, is that ability comes with a no-luck condition, something like this:
Ability modals have a "specific" and a "general" reading. If a pianist is locked in a piano-free cell, they can play the piano in the general sense, but not in the specific sense. Roughly, an agent has the "general ability" to φ if they have the internal constitution required to φ. They have the "specific ability" to φ if, in addition, the external circumstances make it possible for them to φ.
What is the connection between the two notions? Some, e.g. Mandelkern, Schultheis, and Boylan (2017), hold that 'S can φ' expresses specific ability, and that the general reading results from the application of a tacit genericity operator 'Gen'. This is a natural idea, given that general abilities are often called 'general'. (Mandelkern, Schultheis, and Boylan (2017) even call them 'generic'!) The proposal is also tempting for accounts of ability that only directly capture the specific reading. (The locked-in pianist, for example, clearly wouldn't succeed to play the piano if they tried.)
Remember the miners problem. Ten miners are trapped in a mine and threatened by rising water. You don't know if they are in shaft A or shaft B, and you can only block off one of the shafts. Let's not ask about what you ought to do, but about what you can do. Specifically, can you save the ten miners?
According to the simple conditional analysis, you can save the miners iff you would succeed if you tried. So what would happen if you tried to save the miners?
I assume you don't actually try to save the ten miners. You keep both shafts open, knowingly causing the shortest miner to drown. Let's assume that (unbeknown to you) the miners are in shaft A. If you tried to rescue the ten miners, you would arbitrarily choose one of the shafts to block. Let's say you would choose shaft A, simply because you like the letter 'A'. You don't think this is relevant: you don't think the miners are any more likely to be in shaft A than in shaft B. But you have to make your choice somehow. Might as well make it based on your irrelevant preference for the letter 'A'.
A common assumption in discussions of abilities is that phobias restrict an agent's abilities. Arachnophobics, for example, can't pick up spiders. I wonder if this is true, if we're talking about the pure 'can' of ability.
The problem is that 'can' judgements (and 'ability' judgements) are often sensitive to relevant preferences or norms: I might say that I can't come to a meeting (or that I'm not able to come) because I have to pick up my kids from school. This is what I'd call an impure use of 'can'. I don't actually lack the ability to come to the meeting. It's just that doing so would come at too high a cost. Perhaps arachnophobia similarly associates a high cost with picking up spiders.
In my paper "Ability
and Possibility", I argued that ability statements should be analysed as
simple possibility modals: 'S can phi' is true iff S phis at some world
compatible with relevant circumstances.
This view is widely considered inadequate because it seems to violate two
(related) intuitions about ability.
One is that ability requires a kind of robustness: if you have the
ability to phi, then you reliably phi whenever the need arises, under a variety
of circumstances.
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.)
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.
Sometimes, when we say that someone can (or cannot, or must, or
must not) do P, we really mean that they can (cannot, must, must not)
do Q, where Q is logically stronger than P. By what linguistic
mechanism does this strengthening come about?
Example 1. My left arm is paralysed. 'I can't lift my (left)
arm any more', I tell my doctor. In fact, though, I can lift
the arm, in the way I can lift a cup: by grabbing it with the other
arm. When I say that I can't lift my left arm, I mean that I can't
lift the arm actively, using the muscles in the arm. I said
that I can't do P, but what I meant is that I can't do Q, where Q is
logically stronger than P.
Is 'can' information-sensitive in an interesting way, like 'ought'?
An example of uninteresting information-sensitivity is (1):
(1) If you can lift this backpack, then you can also lift that bag.
Informally speaking, the if-clause takes wide scope in (1). The
truth-value of the consequent 'you can lift that bag' varies from
world to world, and the if-clause directs us to evaluate the statement
at worlds where the antecedent is true.
Bob's favourite piano piece is Beethoven's Moonlight Sonata. Alice
would like to play Bob's favourite piece, and she can play the
Moonlight Sonata, but she doesn't know that it is Bob favourite piece,
nor can she find out that it is. Can Alice play Bob's favourite
piano piece?
In one sense yes, in another no. It's a kind of de re/de dicto
ambiguity. Alice can play what is in fact Bob's favourite piece, but
she can't play it "under that description", loosely speaking.
In decision theory, the available options are often glossed informally
as the acts the agent can perform, or the propositions she can make
true. But this yields implausible results in cases where an agent has
doubts about what she can do.
For example, assume Bob suspects that the button in front of him
functions as a light switch, as in fact it does. Then Bob can turn
on the light by pressing the button. But if he is not certain that
the button is a light switch, decision theory should consider the
consequences of pressing the button if it has some other function. So
turning on the light by pressing the button should not count as
an option.
Superficially, modal auxiliaries such as 'must', 'may', 'might', or
'can' seem to be predicate operators. So it is tempting to interpret
them as functions from properties to properties: just as 'Alice jumps'
attributes to Alice the property of jumping, 'Alice can jump'
attributes to her the property of being able to jump, 'Alice may jump'
attributes the property of being allowed to jump, and so on.
Perhaps the biggest obstacle to this approach comes from quantified
constructions. If 'Alice may jump' attributes to Alice the property of
being allowed to jump, then 'one of us may jump' should say that one
of us has the property of being allowed to jump. But while this is one
possible reading of the sentence, 'one of us may jump' also has a
reading on which it states that it is permissible that one of us
jumps. There is a kind of de re/de dicto ambiguity here, which
suggests that 'may' can not only apply to properties but also to
propositions.
According to the Lewis-Nemirow ability hypothesis, knowing what it's like to see red is having a certain cluster of abilities. According to almost everybody who writes about the ability hypothesis, the hypothesis also claims that knowing what it's like neither is nor involves any kind of knowledge-that. This is indeed suggested by some of Lewis' remarks, in particular by this one on p.288 of "What Experience Teaches" (in Papers):
The Ability Hypothesis says that knowing what an experience is like just is the possession of [...] abilities to remember, imagine, and recognize. It isn't the possession of any kind of information, ordinary or peculiar.
One has to read the rest of the paper to find out that by "information", Lewis here most probably means exclusion of possible worlds. At any rate, it is clear from the rest of the paper that Lewis doesn't claim that all Mary learns are abilities.
Via Brian, I came across the recent debate in JPhil on whether knowing-how entails knowing-that. Jason Stanley and Tim Williamson make a good case that it does, but Ian Rumfitt makes an even better case that this holds only for one of the two meanings of "knowing how", namely for the one that translates as "savoire comment [faire]" in French, but not for the one that translates as "savoire [faire]". The former provides by far the most natural interpretation (and translation into French) of "Alex knows how to get to the nearest place selling beer". So the fact that
If Tina is a time traveler who is free to change the past, it must be true that
1) if Tina had chosen 1928, a time traveler would have appeared in 1928.
Moreover, this must be true on a "non-back-tracking" interpretation. A back-tracking interpretation is one on which we consider how past events would have had to be in order to cause some later event. Let's see how (1) fares on Lewis' conditions for non-back-tracking counterfactuals (in "Counterfactual Dependence and Time's Arrow").
The standard solution to worries about time travelers' freedom to 'change the past' rests on a distinction between legitimate and illegimitae facts in such considerations. (See e.g. this great paper by Ted Sider.) Assume for simplicity that x is free to do y iff he really would do y should he decide to do y. Now consider Tina the time traveler. Is she free to kill her earlier self? I.e. is it true that