Why it's bad to kill Grandma

Why it's bad to kill Grandma

Jun 2022


In college, I had a friend who was into debate competitions. One weekend, the debate club funded him to go to a nearby city for a tournament. When I asked him how it went, he said:

Oh, I didn’t have enough time to prepare, so I just skipped the tournament and partied with some friends who live there.

I probably looked a little shocked—I was very idealistic in those days—so he reminded me of our earlier conversations about consequentialism:

This was the right thing to do. There was no way I could participate in the tournament, and they’d already paid for everything. This way I’m happy and they’re happy. Everyone wins!

I got a bit squinty-eyed, but I couldn’t see a flaw. We both agreed it was wrong that he didn’t prepare. But once that was done, was it right to skip the tournament, if consequences are all that matter?


Recently, Arjun Panickssery wrote Just Say No to Utilitarianism, channeling ideas from Brian Caplan, Dan Moller, and Fake Nous. The basis of these articles are thought experiments like this one from Moller:

Grandma is a kindly soul who has saved up tens of thousands of dollars in cash over the years. One fine day you see her stashing it away under her mattress, and come to think that with just a little nudge you could cause her to fall and most probably die. You could then take her money, which others don’t know about, and redistribute it to those more worthy, saving many lives in the process. No one will ever know. Left to her own devices, Grandma would probably live a few more years, and her money would be discovered by her unworthy heirs who would blow it on fancy cars and vacations. Liberated from primitive deontic impulses by a recent college philosophy course, you silently say your goodbyes and prepare to send Grandma into the beyond.

Or here’s a classic, as phrased by Fake Nous:

Say you’re a surgeon. You have 5 patients who need organ transplants, plus 1 healthy patient who is compatible with the other 5. Should you murder the healthy patient so you can distribute his organs, thus saving 5 lives?

The argument is that in some situations, utilitarianism leads to crazy conclusions. Since no decent person would kill grandma, utilitarianism must be wrong.

I’d like to explain why I think this critique of utilitarianism is mistaken.


To step back, what’s the point of ethics?

As far as I know, we live in a universe that’s indifferent to us. Fairness and justice don’t “really” exist, in the sense that you can’t derive them from the Schrödinger equation or whatever. They’re instincts that evolution programmed into us.

But then, when I think about a child suffering, I don’t care about any of that. Whatever the reason is that I think that’s wrong, I do, and it’s not up for debate.

So, while I can see intellectually that right and wrong are just adaptations, I really do believe in them.


Err, so what’s the point of ethics?

If moral instincts are heuristics that evolution baked into us, shouldn’t we expect them to be messy and arbitrary and maybe even inconsistent? Why would we look for a formal ethical system?

My answer is: Because it’s practically useful to do so.

Imagine a space of all possible actions, where nearby actions are similar. And imagine you have a “moral score” for how good you think each action is. Then you can imagine your moral instincts as a graph like this:

actions as points

Here the x-axis is the space of all possible actions. (This is high-dimensional, but you get the idea.) The y-axis is how good you think each action is.

Now, you can picture an ethical system as a function that gives a score to each possible action. Here’s one system:

curve fit to points

Here’s another one:

curve fit to points

Notice something: Even though ETHICAL SYSTEM #2 fits your moral instincts a bit better, it might not seem quite as trustworthy—it’s too wiggly.


I claim that an ethical system is useful when

  1. it mostly agrees with your moral instincts, and
  2. it’s simple/parsimonious.


First, it’s useful for extrapolation. I have strong instincts about killing grandma, but I’m less sure about the moral status of animals, or our obligation to future generations. When we have to make choices about these things, it’s sensible to rely on a simple system that fits with the things we’re sure about.

Second, it’s useful for conflict resolution. Say I claim it’s unconscionable to eat Indian food with chopsticks, but you think it’s fine. If we agree on an ethical system, maybe we can argue about our reasoning. But if I just scream, “this is my irreducible moral instinct!”, good luck.

Third, it’s useful for future-proofing. The ancient Spartans thought that:

The Spartans, of course, didn’t see themselves as evil. They “declared war” on the helots each year, so killing them was totally not-murder. And anyway, if the helots didn’t want to spend their lives being humiliated and terrorized they shouldn’t have allowed their ancestors to lose a war.

The point is, if the Spartans had looked harder, they might have noticed that their behavior seemed to require a lot of ad-hoc justifications. Their ethical system was quite “wiggly”.


The anti-utilitarian crew is right about many things.

  1. You shouldn’t kill grandma.
  2. The reason you shouldn’t kill grandma is that it’s obviously bad to kill grandma. Our moral instincts are the ultimate foundation for ethics.
  3. Few professed utilitarians would kill grandma.
  4. It’s a good exercise to check an ethical system against different situations and look for contradictions.
  5. The utilitarians that “bite the bullet” and accept that it’s right to kill grandma are getting things backward—that’s starting with a rigid ethical system and then imposing it in a situation where you already have strong instincts. What we want to do is take our instincts and then find an ethical system that’s consistent with them.
  6. If utilitarianism tells you to kill grandma, that’s a big strike against utilitarianism.

But does it tell you to kill grandma?


In Economics in One Lesson, Henry Hazlitt says:

The art of economics consists in looking not merely at the immediate but at the longer effects of any act or policy; it consists in tracing the consequences of that policy not merely for one group but for all groups.

Can you tax people to create jobs? Sure, Hazlitt says, but then the people you taxed won’t be able to spend that money and so jobs will be lost elsewhere. Does rent control hold down rents? Of course, Hazlitt says, but it also decreases the production of new housing and increases rents for non-controlled apartments.

(There you go, now you know economics.)

Thinking this way, it’s easy to see the flaw with my friend’s justification for skipping the debate tournament: The people who ran the club could have discovered what happened, in which case they’d stop paying for trips or add new annoying processes to verify that people did as they said. (Also, I wonder if he thought about the effects of telling me what he’d done, in terms of how much I’d trust him in the future?)

Now, the grandma example is constructed to try to avoid those kinds of effects. We postulate that no one will know you killed grandma, and we postulate that her money will save multiple lives with the money.

You could argue about how plausible how assumptions are, but I won’t because I believe in not fighting the hypothetical. Even if it’s unlikely, the situation could arise, and it would be lame to refuse it.


The problem with killing grandma is that nobody wants to live in a world where you kill grandma.

Imagine Utilitopia, a country filled with perfect consequentialists. Any time someone calculates that your organs could generate more utility if they were inside someone else, they are obligated to sneak into your house at night and reallocate your body for better uses.

Might the citizens of Utilitopia be a touch nervous about the fact that they or their loved ones could die at any time?

Now, imagine a ballot initiative to ban involuntary organ harvesting. Of course, the ban would greatly harm some people who need organs. But it would also have momentous benefits for everyone that no longer needs to live in constant fear. It would surely be positive on net.


You might object that I’m cheating—My argument is sort of like this:






Once you’ve made such dramatic concessions, are we still talking about “real” utilitarianism?

Well, it’s always sort of futile to argue about semantics. But how can you not take account of higher-order consequences? People’s horror at killing grandma is a real thing. Trying to give people what they want is literally the definition of utilitarianism.

(And no, it’s not true that utilitarians shouldn’t care about dying, any more than they shouldn’t care about good food or comfortable chairs. Utilitarianism is about meeting people’s needs, not prescribing what those needs are supposed to be.)


Utilitarianism also needs to be tempered in many other ways, like game theory, and the computational complexity of choosing optimal actions.

In practice, commonsense morality is an OK-ish utilitarianism.

Our moral instincts are extremely battle-hardened heuristics. They “know” about all these higher-order issues.

Of course, our instincts are tuned to maximize our descendants, not to maximize total utility. But we may be a bit lucky. We evolved in small tribal bands. In that environment, it could be in your self-interest to risk your life for someone else, since the tribe will reward you with reputation. And it’s against your interest to lie and screw people over since the tribe will punish you with gossip.

The game theory is different in an anonymous megacity. But we’re still mostly operating with our old instincts.


To summarize, I think moral instincts are the starting point, and the goal of ethics is to generalize from them. However, many of the examples people give where utilitarianism “fails” use weak edgy philosophy 101 reasoning. Once you account for higher-order effects, utilitarianism fits reasonably well with commonsense morality.

Many of the other thought experiments fail for similar reasons. Here’s one from Fake Nous:

On his death-bed, your best friend (who didn’t make a will) got you to promise that you would make sure his fortune went to his son. You can do this by telling government officials that this was his dying wish. Should you lie and say that his dying wish was for his fortune to go to charity, since this will do more good?

Response: If people routinely break promises, who will trust those promises?

And here’s another:

You have a tasty cookie that will produce harmless pleasure with no other effects. You can give it to either serial killer Ted Bundy, or the saintly Mother Teresa. Bundy enjoys cookies slightly more than Teresa. Should you therefore give it to Bundy?

Response: Maybe there’s some benefit to knowing that if you kill lots of people, everyone will stop being nice to you?


Technically, I haven’t shown that utilitarianism gives the “right” answer in any of these cases, just that there are extra terms that weren’t being accounted for. That’s fair, but I don’t think I have that burden of proof—I’m just saying that these thought experiments don’t disprove utilitarianism.

You might object that my vision of utilitarianism is so complicated that it’s impossible to apply it. I worry about that. If you don’t like utilitarianism, I suggest this as a strong line of attack! But probably “don’t do anything outlandishly ghoulish unless you’re really sure” can be justified as a good utilitarian rule of thumb.

Finally, you might object that just killing grandma one time won’t make it a routine practice, or that just lying to one person on their deathbed won’t destroy trust.

This last objection is similar to the situations that Derek Parfit worries about: Perhaps it is pointless to donate a liter of water to be divided among 1000 thirsty people since no one can sense the difference of 1 mL? I think this is silly. If enough people donated water, there would clearly be an effect. So unless there’s some weird phase change or something, there’s got to be an effect on the margin.


With all that said, I don’t think I’ve entirely escaped the need to bite bullets. You could imagine a version of Utilitopia where

  1. people didn’t mind the idea that they or their loved ones could be sacrificed for the greater good at any time, and
  2. people could always correctly calculate when utility would be increased, and
  3. no one would ever abuse this power.

You might need more stipulations, but you get the idea. With enough assumptions, a utilitarian eventually has to accept that it’s right to kill grandma.

Fair enough. But I don’t think that proves utilitarianism is wrong. If we’re playing the “arbitrary contrived thought experiments” game, let me propose one:

Grandma is a kindly soul who after a long and happy life is near the end of her days. One morning, Satan shows up in your bedroom and says, “Hey, just wanted to touch bases to let you know that Grandma is going to fall down the stairs and die today. You’re welcome to go prevent that, but if you do, I’ll cause 10% of Earth’s population to have heart attacks and then writhe in agony for ten millennia. Up to you!”

You know that everything Satan says is true. Is it right to let Grandma fall down the stairs?

At some point, you’d have to be crazy not to agree. But, if you’re smart, maybe you shouldn’t admit this? People get happiness from knowing that their loved ones will make irrational—and maybe even immoral (?)—choices to help them. So I suspect we’re dealing with another one of those plans you’re not supposed to talk about.

Comments at substack.

new dynomight every thursday
except when not

(or try substack or rss)