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
    Commented Mar 2, 2022 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
    Commented Mar 2, 2022 at 17:16
  • 1
    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
    Commented Mar 2, 2022 at 18:30
  • @RodolfoAP - this is substantively correct, but it's not entirely a non sequitur just for the reason that the narrator was the one who originally brought up the topic of money. Please see my answer for more. Commented Aug 3, 2023 at 19:09

2 Answers 2


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
    Commented Mar 2, 2022 at 6:34

Your friends' argument is committing the fallacy of "irrelevant conclusion," --but you first opened the door by introducing an irrelevant premise.


Your main statement is the second one "I don't want to waste food (by not eating it)." However, you muddied the waters by first saying "I don't want to waste money."

Your friends are only addressing your first goal, not your second.

They are arguing that a) the money has already been spent, so it cannot be "wasted" at this point and b) that the fun of shoving the cake in your face is at least equivalent to the value of eating it. If you had advanced ONLY the statement about money, this would be a completely valid argument.

But by saying it makes "no difference" they are entirely ignoring your other goal of not wasting food. The correct response to them is:

"You may be right that this is not a waste of money, but it is a waste of food."

It might seem that you have a stronger case if it was your money, not theirs, but they are right that the money is already gone in any case. So the live issue is whether or not the food purchased with the money will be wasted or not. (You could also get into property rights, but that's an entirely different argument, and not necessarily a better one, given that you were going to give them the cake in any case.)

By the way, most debaters will focus on your weakest arguments, not your strongest ones, so it can be a better strategy to advance only your strongest arguments, and leave the weakest ones out entirely.

  • 1
    "By the way, most debaters will focus on your weakest arguments, not your strongest ones, so it can be a better strategy to advance only your strongest arguments, and leave the weakest ones out entirely." Or just don't talk to dishonest debaters who aren't willing to engage everything you're saying in good faith.
    – causative
    Commented Aug 3, 2023 at 19:13
  • @causative - if you have that luxury Commented Aug 3, 2023 at 19:15

You must log in to answer this question.