Lecture: Personal Identity and Free Will
Lecture script · about 15–20 minutes spoken · Week 7
Opening
Picture a band that has played for years. One by one, every founding member has left, and new players have taken their places. The posters still carry the old name, and fans still buy tickets to see the same band. Is it the same band? Hold that question. Half of this lecture grows out of it.
It isn't only a question for music fans. A nursing student caring for someone whose memory is fading asks what keeps a person the same. A criminal justice major asks when a person can be held responsible for a choice. Those are this lecture's two questions: what keeps a self the same over time, and are its choices free?
In Week 2 you learned standard form, validity, and disjunctive syllogism. In Week 4 you met John Locke as an empiricist. In Week 6 you asked what a mind is at one moment. In this lecture I'll ask what keeps a mind, or a person, the same across time, and then whether that person's choices are free. Next week, in Week 8, the midterm review sets each week's key distinction side by side.
1. Two senses of "same"
Picture two new phones from one box. Same model, same color, same glass. In one sense they're the same. In another sense they're two phones: drop one, and the other is fine.
Philosophers name those two senses. Numerical identity is being one and the same thing, so that a thing at one time and a thing at a later time are numerically identical only if they are one thing, not two. Qualitative identity is being exactly alike in every quality, as two new phones from one box can be, while still being two separate things.
Now picture your own phone after two years, with a cracked corner and a new battery. It isn't exactly like the phone you bought. But it seems to be one phone, changed. That's identity over time: the question of whether a thing at an earlier time is numerically the same thing as a thing at a later time, after it has changed.
Pause and try this. Your friend says, "This is the same jacket I wore in high school." Which sense of "same" is that?
Ask yourself: one jacket, or two that look alike?
Here's the answer. It's numerical identity over time, because your friend means one jacket that has lasted and changed, not a second jacket that looks like the first.
2. The ship of Theseus
Now the week's thought experiment. Plutarch's Life of Theseus reports that the Athenians preserved Theseus' ship for a very long time. In John Dryden's translation, "they took away the old planks as they decayed, putting in new and stronger timber in their place". Those English words are Dryden's, the translator's. That's the ship of Theseus: a ship kept for generations by replacing its old planks with new timber. It asks whether a thing whose parts are all replaced is still the same thing.
There are two answers, and each deserves its strongest form. The first says it's the same ship. It was repaired a plank at a time, it kept its shape and its job, and no single repair made a new ship. A tree or a person changes all its matter and stays itself. The second says it's a new ship, because a ship is its timber. Its hard question is where the old ship ended, and its reply is that a vague boundary is still a boundary.
Now a variation, written for this course. Suppose someone saved every old plank and built a second ship from them. Now 2 ships have a claim. The repaired one has the continuity. The rebuilt one has the original timber. The course keys no answer.
Pause and try this. A classmate writes that Plutarch said the Athenians "took away the old planks as they decayed". What needs fixing?
Think about whose English words those are.
Here's the answer. The quotation needs its translator, because the English words are John Dryden's, so it should read "trans. John Dryden".
3. Locke's memory theory
Find a photo of yourself at five years old. Different body, different tastes, almost none of your memories. You still say, "That's me." Why?
That's personal identity: the question of what makes a person at one time the same person as someone at an earlier time. John Locke answered by pointing to the mind. His memory theory is John Locke's theory of personal identity, which holds that a person at one time is the same person as someone at an earlier time if they can remember that person's experiences.
Here's its strongest form, in a variation written for this course. Imagine all your memories were moved into another body. The person who woke up remembering your childhood, your friends, and your last decision would seem to be you. If so, the person goes where the memories go, and the matter of the body isn't what makes you you.
Pause and try this. On the memory theory, is someone in the hospital the same person they were on the day they were admitted, if they remember being admitted?
Apply the definition, word for word.
Here's the answer. Yes, on the memory theory, because they can remember that earlier person's experiences, and that's what the theory says makes them the same person.
4. Pressing the memory theory
You don't remember being two years old. Nobody does. But you seem to be the same person as that toddler. That's the memory theory's sharpest objection. There's a second worry, too: a false memory can feel like a real one.
The memory theorist has a reply, and it's a good one. You remember last year. Last year's you remembered the year before. That year's you remembered the year before that. Picture links in a chain, each one hooked to the next. Overlapping chains of memory connect you to the toddler, even though no single memory reaches that far.
I want to be honest about one thing. Philosophers still argue about the false-memory worry, because calling a memory real may already assume it's a memory of your own past. The course keys no verdict.
Pause and try this. Does the forgetting objection refute the memory theory in its strongest form?
Think about the chain.
Here's the answer. Not by itself, because the chain version doesn't need you to remember everything, only for each stage of you to remember some of the stage before.
5. No-self and the chariot
Think of a river you know. It keeps one name for centuries, but the water in it is never the same from one minute to the next. Nothing in it stays fixed, and still there's a river.
Buddhist philosophy offers a very different answer about the self, and it deserves to be met in its own terms. No-self is the Buddhist teaching, called anatta, that there is no permanent self beyond a changing collection of body, feelings, perceptions, mental formations, and consciousness. That's 5 parts, each one changing.
The Questions of King Milinda makes the point with a chariot. The chariot is the comparison in the Questions of King Milinda of a person to a chariot that is nothing over and above its parts, used to teach that there is no permanent self. The wheels, the axle, the frame: none alone is the chariot, and there's no extra item beside them. "Chariot" names the parts put together. The objection asks who remembers and decides, if there's no permanent self. The reply: memory, choice, and their results belong to the changing collection itself. We'll come back to the chariot in Week 14.
Pause and try this. Does the teaching of no-self say that nothing exists?
Go back to the chariot's wheels.
Here's the answer. No, because the parts exist and so does the changing collection; what the teaching denies is a further, permanent self over and above them.
6. Determinism is not fatalism
Now the second question. Picture a long line of dominoes. Tip the first, and each knocks over the next. Given the setup and how dominoes fall, the last one had to fall.
Determinism is the view that every event is necessitated by prior events together with the laws of nature. Fatalism is the view that what will happen will happen whatever anyone does. They sound alike, but they come apart. Take a domino out of the line, and the last one doesn't fall. On determinism, your choices are dominoes in the line. On fatalism, the outcome comes no matter what you do.
Pause and try this. A student says, "If determinism is true, there's no point studying, because my result is already settled." Which view is the student describing?
Ask whether the studying is one of the causes.
Here's the answer. The student is describing fatalism, because on determinism studying is among the causes of the result, so it isn't idle.
7. Three positions, and hard determinism
The course pins 3 positions on free will. Each answers three questions: is determinism true, does free will exist, and are the two compatible? Here, free will is the power to make choices that are genuinely up to you, of the kind that moral responsibility seems to need.
Hard determinism answers yes, no, no. Libertarianism answers no, yes, no. Compatibilism takes no stand of its own on determinism, and answers yes, yes. So on whether free will exists, 2 say yes and 1 says no. Hard determinism and libertarianism share incompatibilism, the view that free will and determinism cannot both be true.
Hard determinism is the view that determinism is true and that free will does not exist, because free will and determinism cannot both be true. In its strongest form, every choice has causes in your brain, body, upbringing, and surroundings, and those causes have causes reaching back before you were born. The objection: that seems to make blame, praise, and deliberation pointless. The reply: we can still teach, protect people, and change behavior. What goes is only blame that assumes you could have chosen otherwise.
Pause and try this. Which position says determinism is true?
Only one row says yes.
Here's the answer. Hard determinism, because it's the only one of the 3 that answers yes on determinism; compatibilism takes no stand of its own.
8. Libertarianism and the luck objection
Picture yourself choosing between two job offers in two cities. You weigh them for a week, and right up to the moment you decide, both futures feel open.
Libertarianism, in the free will debate, is the view that free will exists and determinism is false; it is a view about choice and causes, not the political view that shares its name. In its strongest form, deliberation really does leave more than one option open, and responsibility needs that openness.
Its hardest test is the luck objection: the objection to libertarianism that a choice prior events do not determine seems to happen by chance, and chance is not control. If everything about you was the same either way, what made it this city and not that one? It starts to sound like a coin toss in your head. The libertarian replies that the person, not a prior event, makes the choice, so it's neither determined nor random.
Pause and try this. Someone hears "libertarianism" and starts talking about taxes. What went wrong?
Think about which debate you're in.
Here's the answer. They've switched to the political view that shares the name, while in the free will debate libertarianism is about choice and causes.
9. Compatibilism and the hypnotist
Think about two people handing over their wallets. One is donating to a cause they love. The other is being robbed. Both acts have causes. Only the first seems free.
Compatibilism is the view that free will is compatible with determinism and that free will exists; it takes no stand of its own on whether determinism is true. A free act, on this view, flows from your own reasons and desires, without force or compulsion.
Now a stage show. A volunteer is hypnotized, and later, when a bell rings, they stand and sing. The compatibilist says that act isn't free, because it flows from the hypnotist's suggestion, not the volunteer's own reasons. A hard determinist answers that every act has causes, and hypnosis only changes which ones. The objection to compatibilism is that your reasons, too, were fixed by events before you were born. Its reply is that freedom asks whether the act came from your own reasons, not whether those reasons had causes.
Pause and try this. Does compatibilism deny determinism?
Look back at its answer on the first question.
Here's the answer. No, because it takes no stand of its own on determinism; its claim is that free will could exist even if determinism is true.
10. An argument about free will
Here's an argument from the course's argument set. It's illustrative: its premises were written for teaching. Either free will is an illusion or determinism is false. Free will is not an illusion. So determinism is false.
One option of the "either, or" is denied, so the other follows. That's disjunctive syllogism, from Week 2, and it's valid. Soundness is never keyed, because its premises are open questions. And here's the lovely part: each position answers it differently. The hard determinist rejects the second premise. The compatibilist rejects the first, since free will can be real even if determinism is true. The libertarian accepts both premises.
Pause and try this. Which premise would a compatibilist reject, and why?
Think about what compatibilism says is possible.
Here's the answer. The first premise, because it assumes free will and determinism can't both be true, and the compatibilist says they can.
11. A Frankfurt case
Many people accept a principle that sounds hard to deny. The principle of alternate possibilities is the principle that a person is morally responsible for what they did only if they could have done otherwise.
In 1969 Harry Frankfurt, in "Alternate Possibilities and Moral Responsibility", described cases that challenge it. Here's a variation on the shape of his cases, written for this course. A person decides, for reasons of their own, to stay late and finish a shared report. Unknown to them, a device was set to make them decide to stay if they'd started to decide to leave. The device never acts. They couldn't have done otherwise, yet they seem responsible for staying. The objection says the device needs some first sign of a decision to leave, so there was still a tiny alternative. Frankfurt's side replies that a flicker that thin isn't the kind of choice responsibility needs.
Pause and try this. In that case, does the device ever make the person do anything?
Listen for what the device does.
Here's the answer. No, it never acts, because the person stays on their own reasons, which is why they still seem responsible.
12. What a self must be for responsibility
Picture a jury asked whether the person in front of them is responsible for something done years ago. That's two questions in one. Is this the same person who acted? And was the act free?
Blaming someone assumes both. The memory theory links the person to the act through chains of memory. No-self says the act and its results belong to the same changing collection, with no permanent self needed. The 3 free will positions then answer whether the act was free. None of them is keyed as correct.
Pause and try this. Can a person be the same person who acted, and still not have acted freely?
Remember the volunteer at the stage show.
Here's the answer. Yes, because the hypnotized volunteer is the same person throughout, but on the compatibilist view the singing didn't flow from their own reasons.
Closing
Let me pull it together. Numerical identity is being one thing; qualitative identity is being alike. The ship of Theseus asks whether a thing survives the replacement of all its parts. Locke's memory theory ties a person to their memories, and overlapping chains answer the forgetting objection. No-self denies a permanent self, not persons. Determinism is not fatalism. Hard determinism, libertarianism, and compatibilism each answer the free will question their own way. Argument 4 is valid, and each position rejects a different premise or none. Frankfurt's cases challenge the principle of alternate possibilities.
Next in this module come the slide deck, the Readings & Resources page, the lecture tutorial, the practice set, the quiz, the discussion, and the assignment. Next week, in Week 8, the midterm review lines up the one distinction each topic asks for, and Pascal's wager asks whether it's rational to bet on belief.
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