Background: It was my birthday, and I had a cake cut party and dinner party. After I cut the first piece of cake and my friends decided to push the cake into my face. But I tried to persuade them not to with this argument:

Hey guys stop it. We bought it with money and would be wasting that money now by just pushing my face in it; I don't wanna waste the food.

To which they argued:

We already bought it so whether we eat it or hit you with it, what difference does it make? We can't get our money back now, so there is no good reason not to.

This argument seems to be flawed, maybe based on a fallacy, but I can't put my finger on it. What is the fallacy in their argument, if one at all?

  • 1
    They shouldn't do it because it is cruel. And cruelty is evil. This is a very fundamental principle in morality.
    – Mary
    Mar 2 at 3:42
  • As others have noted, there isn't any LOGIC error in your "friends'" thinking. Instead, the issue is their MORAL error. Friends should not be trying to humiliate and distress you. If you were writing to an advice column, not a philosophy board, the columnist would be advising you to find yourself a new group of friends!!!
    – Dcleve
    Mar 2 at 17:16
  • Non sequitur. You are talking about the value. They talk about the price (being already paid), which does not follow; it would follow only if they address the value (e.g. it tastes horrible). Also, red herring: they are changing the topic, just for rhetorical argumentation.
    – RodolfoAP
    Mar 2 at 18:30

1 Answer 1


Your friends are accusing you of committing the sunk cost fallacy. Whether they are right depends on whether pushing your face in the cake is preferred over eating it (regardless of what money may or may not have been spent on it in the past). Personally, I would prefer to eat the cake, and I imagine you would as well, but your friends evidently disagree.

You will need to appeal to some ethical system to take this line of reasoning any further than that. For example, Kantian ethics would point out that your friends are using you as a means for their own entertainment, which is wrong because it violates the categorical imperative, or so that ethical system says. Other ethical systems would follow other lines of reasoning, and might come to different conclusions. Utilitarianism would balance the harm done to you against the momentary enjoyment it brought your friends, and compare the net utility of this course of action with the value you would all place on simply eating the cake.

  • Just pointed the link to the section that talks about the fallacy. Thanks for the info!
    – J D
    Mar 2 at 6:34

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