What are the philosophical arguments / frameworks that view at least seemingly consensual activities (e.g incest, killing (assisted suicide or dueling), mutilation, gay sex ) involving one or more autonomous agents as immoral? Why do they think such acts are wrong?

Again, do any common philosophical views believe consensual acts are wrong?

  • I'm not really sure what happened in the comments. But the comments are not really for extended discussions. There's something that seems to have turned into a nasty argument and there was a clarification that the OP's list is things the OP thinks are fine (rather than being a closeted attempt to include gay sex with the unacceptable acts). I've taken the liberty of removing sex with animals from the list ... and editing the question in general to try to make it clearer.
    – virmaior
    Commented Aug 25, 2015 at 13:20

4 Answers 4


I certainly think you could have a coherent, viable moral system based around this principle; in many ways we already do in the concept of free will and recognition of and respect for other people as free-willed subjects. In fact, in the evolution of secular ethics this could be considered a real trajectory.

I do not think such a system would be acceptable to everyone; it is ontologically problematized in a religious context, if "the consent of those involved" extends into the supernatural.

However, I think many people could frame the exact same moral choices they make already in this context, given the appropriate conceptual framework. It provides a foundation for moral discussion by making us ask questions like, "Who's consent is required?" (i.e., who's really involved) and "Who's capable of consenting?" (to allow for excluding children and the mentally unfit). Applying that, I'll tackle a few of the problem/counter cases from elsewhere in this Q&A.

  • A potperri list from the original question: "incest, [...] mutilation, gay sex, sex with animal". You can get consent to have gay sex, so that is pretty straight forward. You cannot get consent from an animal to have sex, although whether that makes it morally wrong is complicated by the fact that we do lots of nasty things to animals without their consent. With regard to incest, the prohibition is largely because we know there is an increased rate of birth defects. Hence, this is really a question about whether it is moral to risk pregnancy when there is a significant risk of birth defects; beyond that I don't see anything immoral about incest, if it is consensual, between adults, etc.

    Regarding mutilation, this needs to be defined more specifically, but it sort of goes along with freedoms we already consider essential. Should smoking be completely banned because some people die from it? Then what about automobiles, electricity, and red meat? All of these can be fatal no matter how many precautions you take. Can I safely chop off a finger? Who's consent do I need if the answer is no? Who's consent if it is yes?

    I also think the mutilation question is more complex than it might seem at first glance. Can self-immolation (which crosses over into the next point...) as political protest be considered a moral act, at least under some circumstances? If so, couldn't there be forms of self-mutilation that line up with this? What about throwing yourself under a tank?

  • That suicide cannot be easily condoned because of regrettable errors in judgement, etc. I think the more significant case here is actually assisted suicide, and there's no reason we could not regulate this to mitigate against mental illness, etc. by committing to the consent/judgement of several involved people.

    It can still be applied to cases of lone suicide, however. If I provide for my young family, who stand to suffer and perhaps even starve without me, it is possible to inject the concept of consent as a moral responsibility and deal with all the things we would normally want to consider in such a case.

  • "..consensual sex between someone with AIDS and a partner married to someone else" -> As the author points out, this puts a further person at risk, and in-so-far as that is true this other person is involved. The mistake is to then say that the consent of this involved person isn't necessary. Likewise, any form of adultery without consent from your partner is a violation of a trust, and any such violation of trust is so because consent was not given in a situation where it might reasonably be considered prerequisite. I loaned you my car, but you purposefully driving it into a lake was such a non-consensual violation of trust, regardless of whether there were other people in the car who thought it was okay.

  • "Could any reasonable person get consent from everyone else on the Mississippi river?" Implies that if we consider consent to be too difficult to achieve, then we can set it aside without having to feel morally compromised. But ethics is not something we apply only when it is convenient for us. Might it become very difficult to get certain things done to the Mississippi River if we had to admit a moral responsibility requiring consent from a large number of people? It might, but that is sort of the point of morality -- to bind our behaviour to a certain standard.

  • The way you take someting is not what it implies.
    – user9166
    Commented Aug 22, 2015 at 15:24
  • "any form of adultery without consent from your partner is a violation of a trust" - although not all kinds of marriage restrict sex with other persons. Take open marriage. Thus it's wrong to call it (the extramarital sex itself) violation of trust. But anyway point on AIDS and comparison with car make sense.
    – rus9384
    Commented Apr 9, 2018 at 8:29
  • @rus9384 An open marriage is consentual. Unless only one of the partners knows about it, lol, in which case it would seem morally questionable. Commented Apr 9, 2018 at 13:35
  • Lol, you cannot be in open marriage if haven't declared so. Well, it's only annoying that relationships and marriage are closed by default...
    – rus9384
    Commented Apr 9, 2018 at 13:40

There are philosophical frameworks in which "consensual" activity is still illicit. Consider these two examples:

Under the umbrella of deontology, there are a couple different groups that say (for various different reasons) that certain behavior is simply against "the rules." Since they are against the rules, it doesn't matter if the action is consensual. (Where those rules come from is its own interesting question.)

A teleological approach toward philosophy looks at whether a thing is being used to its appropriate end. Under this way of thinking, consent is not enough - the action must be in compliance with a thing's end.


Consent has got nothing to do with it. It's about intent and consequences. In fact, it's really only about intent, as that implicitly takes care of consequences, but I don't want utilitarians do get their panties in a bunch, so I'll just add consequences in separately.

If you decide to get together with your gossip buddy and talk trash about other people, that's consent. But are the intentions ethical?


In modern age, there is this idea that consent of parties or free-will are to be respected.

A Gazillion outcomes can come out of this that are wrong.

Kids and teens make this mistake all the time, they agree on things that are wrong for themselves and for others, same could be said for adults too. Adults because they are adults, does not constitute that they make right decisions for themselves or for the society. I as an adult make wrong or evil decisions from time to time, I am sure that all humans do!

Basically there are three rights that need to be addressed, to me free-will and consent cannot undo the rights of yourself, others or God. You can only use your free-will to the extent that it doesn't conflict with any entity's rights.

  • Right of yourself. Can your consent be against your own good?
  • Right of people.Can your consent be against the people? E pluribus unum
  • Right of God. Can your consent be against the giver of everything?
  • This is dogmatic and lacks any argument whatsoever. What if your simply wrong?
    – Lukas
    Commented Aug 25, 2015 at 13:38
  • I never said they are wrong, I said by that logic many wrong things could come out. As long as your consent is not breaching any entity's rights, then you are good to go!
    – Honey
    Commented Aug 25, 2015 at 16:33

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