What Does It Mean to Have an Ability?

Here’s a strange thing philosophers noticed. You can probably wiggle your ears—or at least, you could learn to. You cannot, however, fly by flapping your arms. But what exactly is the difference between these two situations? What does it mean to say that someone has the ability to do something?

You might think the answer is simple: you have an ability if you would succeed if you tried. If you try to wiggle your ears, maybe you can. If you try to fly by flapping your arms, you definitely can’t. But philosophers have discovered that this simple answer gets complicated very quickly. And the complications matter—not just for abstract philosophy, but for understanding free will, moral responsibility, and even what it means to have a disability.

What Kind of Thing is an Ability?

Abilities belong to a larger family of properties called powers. A glass has the power to break when struck—that’s a disposition. A trail has the power to be walked on—that’s an affordance. But abilities are special. They belong only to agents (creatures who can act, not just be acted upon), and they connect those agents to actions.

So your ability to speak French is an ability, because speaking is an action. Your ability to understand French is not an ability in this strict sense—understanding is something that happens to you, not something you do. That might seem like nitpicking, but it matters when philosophers start building theories.

The Simple Idea: “You Can If You Would”

For a long time, many philosophers thought they had a straightforward theory of ability. It goes like this:

You have the ability to do something if and only if you would do it if you tried.

This is called the conditional analysis, because it says having an ability depends on a conditional statement: “If X tried to do it, X would succeed.” It’s a very appealing idea. It explains why you can raise your arm (if you tried, you would), and why you can’t fly (if you tried, you wouldn’t).

The philosopher David Hume seemed to have something like this in mind when he wrote about freedom. He said that liberty is just “a power of acting or not acting, according to the determinations of the will”—if you choose to stay still, you can; if you choose to move, you can. He thought this was so obvious that nobody could deny it.

But then the counterexamples started piling up.

The Problem of the Phobic Candy

Imagine someone who has a terrible phobia of red sugar balls—they remind them of drops of blood. If you offered them a bowl of candy containing red sugar balls, they wouldn’t take one. But here’s the strange thing: if they tried to take one, they probably would succeed. Their hands work fine. The conditional analysis says they have the ability to take a red candy. But intuitively, they can’t—their psychological block makes it impossible for them.

This shows that the simple conditional analysis is too simple. It doesn’t account for the fact that internal obstacles (like phobias) can destroy abilities just as surely as external obstacles (like handcuffs).

The Problem of the Good Golfer

Now consider a skilled golfer who misses an easy putt. She tried to make it, but she didn’t. The conditional analysis says she doesn’t have the ability to make that putt—after all, she tried and failed. But that seems wrong. She’s a good golfer! She has the ability; she just didn’t exercise it successfully this time.

Philosophers sometimes handle this by distinguishing between general and specific abilities. The golfer has the general ability to sink putts like that—she’s done it many times before, and she’ll do it again. But in this specific moment, with the wind and the pressure and whatever else, she lacked the specific ability. The conditional analysis, the defender might say, is trying to capture specific ability, not general ability.

A More Sophisticated Approach: Dispositions

Some philosophers noticed that the problems with the conditional analysis of ability look a lot like problems that come up when analyzing dispositions—things like fragility or solubility. Consider a glass that’s fragile but happens to be stuffed with styrofoam packaging. If you struck it, it wouldn’t break—the packaging would prevent that. But the glass is still fragile. The simple conditional (“it would break if struck”) fails, just like the simple conditional about ability fails.

This led a group of philosophers (sometimes called the “new dispositionalists”) to suggest that abilities are a kind of disposition. Michael Fara put it like this:

You have the ability to do something in circumstances C if and only if you have the disposition to do it when, in circumstances C, you try.

This is more sophisticated than the simple conditional analysis, but it still faces problems. Critics ask: if there’s something in place that would prevent you from succeeding if you tried, and you have no control over that thing, do you really have the ability? Or do you just have some kind of competence that can’t be exercised?

Another Idea: Ability as Possibility

A different family of theories says that having an ability is just a matter of possibility with some restrictions. The idea is simple: you’re able to do something if it’s possible for you to do it, where “possible” means something narrower than “logically possible” or even “physically possible.”

This is called the modal analysis, and it comes in many versions. The trick is figuring out exactly what the restriction should be. Should we consider only worlds where the past is the same as actuality? Only worlds where the laws of nature are the same? Only worlds where the agent’s psychology is intact?

The philosopher Angelika Kratzer suggested that the answer depends on context. When someone says “Jane can ride her bike,” what matters depends on why we’re asking. If her bike was stolen, in some contexts we’d say she can’t ride (she has no bike); in others we’d say she can (she knows how, she just needs a bike).

A Logical Puzzle

The philosopher Anthony Kenny raised a clever objection to the modal analysis. He pointed out that ability doesn’t behave the way possibility normally does in logic.

Consider: if you have the ability to do A-or-B, does it follow that you have the ability to do A, or that you have the ability to do B? Not necessarily. Kenny gave this example:

Given a deck of cards, I have the ability to pick out (on request) a card that is either red or black. But I don’t have the ability to pick out a red card on request, nor the ability to pick out a black card on request.

Why not? Because you could succeed at picking “red or black” by using a strategy—say, always pick the top card—without having any control over which color you get. You can’t guarantee red, and you can’t guarantee black. But the modal analysis, if it treats ability like ordinary possibility, would say: if you can do A-or-B, then either you can do A or you can do B. That doesn’t seem right for ability.

This gets technical, but here’s what it accomplishes: it shows that ability isn’t just a kind of possibility. There’s something about control that matters. An agent needs to be in charge of what they’re doing, not just a lucky bystander when things go right.

Newer Ideas: Two-Way Powers and Options

Some contemporary philosophers have given up on the idea that ability can be analyzed in terms of conditions or possibilities at all. They think ability is a fundamental feature of agents that can’t be reduced to anything else.

Helen Steward argues that agents have “two-way powers”—powers that an agent can either exercise or not, even if all prior conditions are exactly the same. A glass, when struck, must break (if it’s fragile and nothing prevents it). But an agent, when faced with a choice, can genuinely do either thing. This two-way-ness is what makes agency special, and it’s what makes ability irreducible.

John Maier suggests thinking about abilities in terms of options. An option is an action that’s genuinely open to you at a given moment. Having a general ability, on this view, just means having a particular pattern of options over time. This doesn’t reduce ability to anything else—it just says what kind of thing ability is.

Why All This Matters

Free Will

The biggest reason philosophers care about ability is because of the free will debate. The question is: if determinism is true (if everything that happens is caused by what came before, like a giant chain of dominoes), can we still have the ability to do other than what we actually do?

Some philosophers argue “no.” If the past and the laws of nature determine everything, then you couldn’t have done otherwise—you lacked the ability. Others argue “yes”—perhaps ability is compatible with determinism, because what matters is whether you would have succeeded if you’d tried, not whether the universe could have unfolded differently.

Here’s the tricky part: if you try to defend compatibilism (the view that free will and determinism can coexist) by offering a theory of ability, you need that theory to be correct independently of the free will debate. You can’t just assume the theory that makes your position easy. As philosopher Peter van Inwagen pointed out, the incompatibilist’s arguments are also arguments against the compatibilist’s theory of ability.

Moral Responsibility

This connects to a famous puzzle called “Frankfurt cases.” Imagine someone who decides to do something, but there’s a hidden device in their brain that would have forced them to do it if they’d decided otherwise. The device never activates—they chose freely. But could they have done otherwise? Most people say no—the device would have stopped them. If that’s right, then it seems like someone can be morally responsible even if they couldn’t have done otherwise. That challenges the old idea that responsibility requires alternative possibilities.

But some philosophers push back. If ability is a disposition, they say, the agent does have the general ability to do otherwise—it’s just that this ability is “masked” by the device, just like the fragile glass’s disposition to break is masked by packaging. Whether this response works depends on whether we think general ability or specific ability is what matters for responsibility.

Disability

Theories of ability also matter for understanding disability. Some philosophers think that having a disability just is lacking certain abilities. On this view, a deaf person is disabled because they lack the ability to hear, which most humans have.

But this gets complicated quickly. Is the loss of ability what makes disability bad? Some disability activists argue that disability is not a “bad difference” at all—it’s just a difference, and one worth celebrating. If ability-based views of disability imply that losing an ability is always bad, they might conflict with this perspective.

There are also cases that are hard to fit into ability-based views. What abilities does someone with chronic fatigue or fibromyalgia lack? It’s not obvious. Maybe they lack the ability to perform temporally extended actions (like working a 40-hour week), even if they can do each individual step. But that stretches the concept of ability in new directions.

Still an Open Question

After all this, philosophers still disagree about what abilities are. The conditional analysis is too simple, the modal analysis faces logical puzzles, and the newer power-based views are still being developed.

What most philosophers do agree on is this: abilities involve some kind of control or agency. They’re not just about what might happen or what would happen if conditions were different. They’re about what the agent herself can bring about, in a way that’s genuinely up to her.

The puzzle is figuring out what that “up to her” amounts to—and whether it can survive careful philosophical scrutiny.

Appendix: Key Terms

Term	What it does in this debate
Ability	A power of an agent that relates to an action
Disposition	A power of an object (like fragility) that’s similar to but not the same as ability
Conditional Analysis	The theory that having an ability means you would succeed if you tried
Modal Analysis	The theory that having an ability means it’s possible for you to do it, in some restricted sense
General ability	An ability you have even when conditions aren’t right to exercise it (like knowing how to serve even without a tennis racket)
Specific ability	An ability you have when you’re actually in a position to exercise it (like being on the court with a racket)
Two-way power	A power that an agent can either exercise or not, even holding all prior conditions fixed

Appendix: Key People

David Hume (18th-century Scottish philosopher): Argued that freedom is just the power to act according to one’s choices, which he thought was obviously compatible with determinism.
Keith Lehrer (20th-21st century American philosopher): Came up with the phobic candy counterexample that helped show the conditional analysis is too simple.
Anthony Kenny (20th-21st century British philosopher): Showed that ability doesn’t behave logically like ordinary possibility, which challenges the modal analysis.
Helen Steward (contemporary British philosopher): Argues that agents have “two-way powers” that can’t be reduced to dispositions or possibilities.
Peter van Inwagen (contemporary American philosopher): Argued that compatibilists can’t just assume their theory of ability is correct—they need to defend it against arguments that ability is incompatible with determinism.

Appendix: Things to Think About

Think of something you can do but sometimes fail at (like making a free throw in basketball, or solving a particular type of math problem). Do you “have” the ability even when you fail? When you succeed, do you “have” it then? What would it mean for ability to come and go that fast?
The conditional analysis says ability is about what would happen if you tried. But can you try to do something without being able to? Can you fail to try to do something you’re able to do? What does that tell us about the relationship between trying and ability?
Suppose a super-intelligent scientist could predict everything you’ll ever do. Does that mean you lack the ability to do otherwise? Or could you still have the ability, even though the scientist knows you won’t use it? What difference does the scientist’s knowledge make?
If having more abilities is always good, then lacking abilities is always bad. But is having more abilities always better? Would you want the ability to accidentally hurt people? The ability to cheat on tests? What does this tell us about the value of abilities?

Appendix: Where This Shows Up

Sports and competition: Coaches talk about whether a player “has the ability” to make a shot, which matters even when they miss. The distinction between general and specific ability plays out in real time.
Artificial intelligence: When we say AI “can” write an essay or “can” solve a math problem, are we using the same concept of ability we use for humans? Or is something different going on?
The law: Courts sometimes need to decide whether someone “was able” to do something—for example, whether a person could have prevented an accident. Legal definitions of ability matter for assigning responsibility.
Medicine and rehabilitation: Therapists assess what abilities a patient has and what they’ve lost. Different theories of ability might lead to different judgments about recovery and disability.