Here’s a very quick moral dilemma.

Let’s assume that in the absence of previously established consent (as, for example, might exist between a married couple), it’s morally wrong to have sex with somebody if they’ve ingested some X  amount of alcohol (because it undermines their ability to give informed consent). For the purposes of this dilemma, it doesn’t matter what this amount is – just that there is some amount.

Okay, so this is the twist. Suppose somebody says this to you:

I want to want to have sex with you, but I never want sex unless I’m high or drunk. I can’t relax and I don’t enjoy it. But look, I’ll start drinking, and hopefully there will come a point where my inhibitions are sufficiently lowered and I’m relaxed enough so that we can go ahead. But realize I’m not consenting right now to have sex with you later, I’m simply telling you that I’m making the choice to drink in the hope that I will come to want sex later on. If that happens, I’ll let you know, but it might not.

This person then starts drinking, ingests some X + 1 amount of alcohol (i.e., past the point at which under normal circumstances you would consider it wrong to have sex with them), and then tells you they are ready to have sex with you.

We need to get clear about a few things before posing the (obvious) question.

First, this person is not approaching unconsciousness, they are able to reflect reasonably cogently on their desire to have sex with you, but it’s counterfactually true that in the absence of the alcohol, they would not have consented, and also that this would be true of some non-trivial percentage of other people who had drunk this much, even in the absence of the particular psychological dynamic that exists here. (I realize that this stipulation might conflict with the claim that it doesn’t matter for the purposes of this dilemma at what point alcohol undermines the ability to consent. If you think this happens when somebody approaches unconsciousness, then just assume it’s been stipulated that it occurs earlier than that.)

Second, this person would deny that they are psychologically vulnerable. They would be offended if anybody suggested that they were being taken advantage of just because they never want sex while sober. They know their own mind – they want to want to have sex.

Third, you have no particular reason to think they will come to regret any sexual encounter that takes place. They might, but they might not.

So the question is: In this situation, would it be wrong to go ahead with the sexual encounter, and if so, why?

Jeremy Stangroom co-founded The Philosophers’ Magazine with Julian Baggini.