Whose Life Is It, Anyway? When Your Past and Future Selves Disagree

Imagine you’re thirteen years old. You love video games, hate broccoli, and think your little brother is annoying. Now imagine that somehow you could travel forward in time and meet yourself at age thirty. That future you might have different taste in games, might actually like broccoli, and might think your little brother is their best friend. Would that future person still be you? And if they are, who gets to decide what’s best for you right now — the thirteen-year-old who hates vegetables, or the thirty-year-old who can’t get enough of them?

That’s a strange thought experiment. But for doctors, families, and philosophers, a real version of this question comes up all the time. It happens when someone used to be able to make their own medical decisions, but then lost that ability — maybe from Alzheimer’s disease, a severe stroke, or a brain injury. Before they got sick, they might have written down what they wanted (this is called an advance directive). But now, in their current state, they seem to have new feelings and interests that conflict with what they used to want. What should happen?

This is a genuinely hard problem, and nobody has fully solved it.

Two Ways to Decide for Someone Who Can’t Decide

When a patient can’t make their own medical decisions, the law recognizes two main approaches for how a family member or doctor should decide for them.

The first is called Substituted Judgment. The idea is simple: figure out what the patient themselves would have wanted, and do that. If your grandmother always said she never wanted to be kept alive by machines, then don’t put her on machines. This approach tries to respect her past wishes. It’s based on the idea that respecting someone’s autonomy — their right to make their own choices — is really important, and we should keep respecting that even after they can’t choose anymore.

The second approach is called Best Interests. Here, the decision-maker tries to figure out what’s objectively best for the patient right now, regardless of what they might have said in the past. This usually means focusing on things like avoiding pain, staying comfortable, and having a decent quality of life. This approach is based on beneficence — the duty to do good for someone.

Most experts and laws say that Substituted Judgment should come first, whenever possible. If we know what the patient wanted, we should follow that. We should only fall back on Best Interests when we have no idea what the patient would have chosen.

But this picture gets complicated when the patient used to be capable of making decisions but no longer is — what philosophers call the formerly competent. Because now we have a conflict across time.

The Conflict: Your Past Self vs. Your Current Self

Here’s the core puzzle. Consider someone named Maria. In her fifties, Maria is a professor who strongly identifies with her intellect. The thought of living with dementia terrifies her — she sees it as degrading. So she writes an advance directive saying: if I ever develop Alzheimer’s, do not prolong my life. Please, just keep me comfortable and let me go.

Twenty years later, Maria has moderate Alzheimer’s. She no longer remembers being a professor, or what dignity meant to her, or that she ever wrote that document. But here’s the thing: she still enjoys things. She likes listening to music. She finds pleasure in gardening. She laughs with her grandchildren when they visit, even though she doesn’t quite remember who they are. When you ask her if she wants to keep living, she seems happy and engaged.

What should her family do? Honor Maria’s past wishes and let her die? Or honor what seems to be her current interest in living?

This is the central problem. The earlier Maria — let’s call her Maria₁ — had strong interests. She cared about dignity, about the shape of her life, about not being seen in a degraded state. The current Maria — Maria₂ — has different interests. She cares about simple pleasures, about feeling good, about connection. These two sets of interests conflict. The advance directive was supposed to settle things, but now it looks like following it might hurt the person who actually exists.

Giving Authority to the Past Self

Some philosophers think that Maria₁’s wishes should still win. They argue that the earlier, more capable self has a special kind of authority over the later, less capable self. The idea is that once someone falls below a certain threshold of mental capacity — once they’re no longer truly autonomous, or no longer a “person” in the full sense — their current interests don’t carry the same weight. What really matters is what the person (the full, autonomous person they used to be) wanted for their own life.

Ronald Dworkin, a famous legal philosopher, defended this view. He argued that when someone loses the capacity for autonomy entirely, their earlier interests — especially what he called “critical interests” (not just what feels good, but what gives life meaning and shape) — remain their most important interests. Even if Maria₂ can’t understand why dignity mattered to Maria₁, it still matters for her, because she is still the same person. And her autonomous self’s decisions should govern her non-autonomous state.

This is a powerful idea. It takes the person’s own deepest values seriously, even when that person can no longer hold those values. It says: your past commitments aren’t just forgotten just because you can’t remember them. They’re still yours.

Why That Might Be Wrong

But other philosophers push back hard. Here are some of their objections.

Objection 1: Decisions are about the present and future, not the past. When a doctor or family member decides for Maria, they’re deciding about what happens to her now and from now on. You can’t change the past. So why should past wishes dictate present decisions? Maybe it’s sad that Maria₁’s hopes were left unfulfilled, but you can’t fix that by harming Maria₂.

Objection 2: Maybe the past self doesn’t have that much authority after all. Some philosophers, like Seana Shiffrin, argue that what really matters for autonomy is the ability to exercise your own will — to make choices, have preferences, and control your own experience. If Maria₂ can still do that — if she can still say “I want to listen to this music” or “I want to stay alive” — then her current choices have authority. The past self can’t just override them.

Objection 3: Maybe the “past self” and “current self” aren’t even the same person. This is the wildest challenge. Some philosophers think about personal identity in terms of psychological continuity — the connections of memory, personality, values, and so on. If Alzheimer’s wipes out enough of those connections, maybe Maria₁ and Maria₂ aren’t the same person at all. They just happen to share a body. If that’s true, then letting Maria₁ dictate what happens to Maria₂ would be like letting a dead person control a living one. That seems wrong.

Objection 4: Even if they’re the same person, maybe the connection between them is too weak. Jeff McMahan, another philosopher, argued that even if we accept that Maria₁ and Maria₂ are numerically the same person, the psychological ties between them are so thin that their interests should be treated as largely independent. Maria₁’s concern for herself at the Alzheimer’s stage shouldn’t be very strong, because there’s so little continuity. So when their interests conflict, it’s not obvious that Maria₁’s wishes should win.

The Messy Middle

So who’s right? The honest answer is: philosophers still argue about this.

Some think the past self should always win, because autonomy is the most important value, and the past self was the one capable of real autonomy. Others think the current self should often win, because what matters is the actual living, breathing person in front of you, who has real feelings and interests right now. Still others try to split the difference: maybe it depends on how severe the mental decline is, or on how important the competing interests are.

Here’s one more twist. Even among people who think the current self should sometimes win, there’s disagreement about why. Is it because the current self is a “person” with rights, and you can’t violate a person’s rights just to satisfy someone else’s wishes (even if that someone else is your past self)? Or is it because the current self’s interests — in survival, in pleasure, in connection — are genuinely weighty, and sometimes weightier than the past self’s interest in having a certain kind of life story?

And what about patients who were never capable of making autonomous decisions — children, or people born with severe cognitive disabilities? For them, there’s no past autonomous self to appeal to. The Best Interests standard seems like the only option. But even there, philosophers ask: can we still reconstruct something like their own viewpoint? If a child with intellectual disabilities can’t make complex medical decisions but clearly values certain things — like painting, or being with her family — shouldn’t those values guide decisions about her care? The answer is probably yes, but it’s a complicated yes.

The Real Takeaway

Here’s the thing this whole debate reveals: who you are over time is not as simple as it seems. You change. Your values change. Your memories fade. New experiences give you new priorities. We all assume there’s a single “you” that persists from childhood to old age, but when you look closely at how much people can change — especially through disease or brain injury — it becomes hard to say exactly what that means.

And if it’s hard to say what it means for you to be the same person over time, it’s even harder to say what it means for your past self to make decisions for your future self.

Advance directives are still useful. They’re the best tool we have for giving people control over their own futures. But they have limits. They can’t foresee everything, and they can’t resolve the deep tension between respecting someone’s past autonomy and caring for their present well-being.

So the next time someone tells you “it’s my life, I can decide what happens to me,” you might ask: which “me”? The one you are now, or the one you used to be, or the one you’ll become? And if those three “me”s disagree about what’s best, whose life is it, anyway?

Appendices

Key Terms

Term	What it does in this debate
Advance directive	A document someone writes while competent, saying what medical treatments they want or don’t want if they lose the ability to decide later.
Substituted Judgment	The approach where a surrogate tries to figure out what the patient themselves would have wanted, and decides accordingly.
Best Interests	The approach where a surrogate decides based on what’s objectively best for the patient’s well-being right now.
Autonomy	A person’s right and ability to make their own choices about their own life.
Beneficence	The duty to do good for someone, to act in their best interests.
Personal identity	The philosophical question of what makes someone the same person over time.
Prudential concern	The special kind of care we have for our own past and future selves — it’s different from how we care about anyone else.
Threshold of capacity	An imagined line: above this line, someone’s current interests have authority; below it, their past interests might take over.

Key People

Ronald Dworkin — A legal philosopher who argued that when someone loses the capacity for autonomy, their earlier autonomous wishes should still govern their care, because those wishes express their most important interests.
Seana Shiffrin — A philosopher who pushed back against Dworkin, arguing that even a reduced ability to make choices and exercise your will deserves respect and protection.
Jeff McMahan — A philosopher who argued that psychological connections between our past and future selves can be so weak that we should treat their interests as largely independent, even if we’re technically the same person.
Agnieszka Jaworska — A philosopher who argued that the “capacity to value” (not just to choose) marks the crucial threshold, and that people in moderate dementia who still value things deserve to have their current interests respected.

Things to Think About

If you wrote an advance directive at 30 saying you never wanted to be kept alive in certain circumstances, but at 70 you seemed happy and wanted to stay alive, which version of you should win? Does your answer change if the later you is clearly suffering? If they’re clearly content?
What makes someone the “same person” over time? Is it their memories? Their personality? Their body? Their values? What if all of those change?
If a person with severe dementia seems perfectly happy in the moment, but earlier in life said they’d rather die than live that way, are we respecting them by keeping them alive? Or are we disrespecting them by ignoring their past wishes?
Should children have a say in their own medical treatment, even if they can’t fully understand the consequences? At what age should that count? Does this connect to the debate about formerly competent adults?

Where This Shows Up

Hospital ethics committees regularly face these conflicts when a patient’s advance directive says one thing but the patient now seems to want something else.
Alzheimer’s advocacy groups debate whether advance directives from early-stage patients should override the apparent wishes of late-stage patients.
Disability rights activists sometimes worry that advance directives can be used to end the lives of people with disabilities, whose lives might be valuable even if they don’t fit the “competent autonomous person” ideal.
You already face this in smaller ways: when you promised your friend you’d do something, but now you don’t want to. Are you bound by your past promise, or free to change your mind? (The stakes are lower, but the structure is similar.)