There are many avenues of exploring consent in philosophy. For instance, in the philosophy of sexuality (IEP), consent is tremendously important. So too, in the intersection of morality and bioethics (SEP) is the question of informed consent pivotal. Lastly, in the philosophy of law (SEP), the notion of consent is relevant in establishing mens rea. It's obvious that the notion of consent is an important philosophical matter.

So, broadly, if someone does not "consent" to something that happens to them, and they change their mind and then change their mind and do or did "consent" to this something in the middle of the act or after the act has already occurred, how is that "consent" viewed? For instance, would it be invalid and considered not consent? I know the philosophy of mind demonstrates a broader picture, but specific examples would be helpful.

  • Depends on multiple variables. A kid might consent to use a toy after he has been tricked to try it. If you search for a legal perspective, this is not the right place.
    – RodolfoAP
    Mar 1, 2022 at 20:16
  • 1
    This question belongs on a legal blog. Mar 1, 2022 at 20:42
  • @DavidGudeman I've retracted my snark. My apologies. :D I've fortified the question to show how important consent is across a range of philosophical matters.
    – J D
    Mar 4, 2022 at 12:54
  • @JD, thank you. Mar 4, 2022 at 17:56

2 Answers 2


I really wanted to give a nice elaborated answer to this question but I don't have enough time right now. So here's my short, quick answer:

From the perspective of Philosophy of Language, there's a lot to say about your question.

Firstly, in Bad Language, Herman Cappelen offers an entire chapter on "The Speech Act of Consent" (chapter 11). This text explores definitions of consent (first introduced as "a speech act whereby we agree that something is true", but then gradually expanded in depth and scope), walks through many examples and considers how it works. There are a few examples of sexual activity policies in universities (in the context of preventing sexual assault), where your specific question is partially addressed:

Consent to some sexual acts does not constitute consent to others, nor does past consent to a given act constitute present or future consent. Consent must be ongoing throughout a sexual encounter and can be revoked at any time.

Cappelen, Herman; Dever, Josh. Bad Language (Contemporary Introductions to Philosophy of Language) (p. 184). OUP Oxford. Kindle Edition.

Then various problems are explored.

  • What counts as an individual sexual act that requires consent renewal?
  • Can deception undermine consent?
  • How does implicit consent work?
  • When is explicit consent required?
  • The difference between tacit consent and silencing (or "silencing" vs. "being silent")

And toward the end the chapter describes the inherent complexities in the act of consent, and its dynamic nature.

Secondly, in Sexual Solipsism, Rae Langton discusses the complex topic of sexual violence and its connection to consent and how pornography can shape human behavior related to it (in chapter 1.2. "Pornography Silences")...

Example (5): Refusal. Consider the utterance 'no'. We all know how to do things with this word. We use it, typically, to disagree, to refuse, or to prohibit. In sexual contexts a woman sometimes uses it to refuse sex, to prohibit further sexual advances. However, in sexual contexts something odd happens. Sometimes a woman tries to use the 'no' locution to refuse sex, and it does not work. It does not work for the twenty percent of undergraduate women who report that they have been date raped. It does not work for the twenty-five percent of final-year schoolgirls who report that they have been sexually forced." Saying `no' sometimes doesn't work, but there are two ways in which it can fail to work. Sometimes the woman's hearer recognizes the action she performs: i.e., he recognizes that she is refusing. Uptake is secured. In saying 'no', she really does refuse.

By saying 'no', she intends to prevent her hearer from continuing his advances. But the hearer goes ahead and forces sex on the woman. She prohibits, but he fails to obey. She fails to achieve the goal of her refusal. Her refusal is frustrated. 'Perlocutionary frustration' is too meek and academic a label for what is simple rape. Sometimes, though, there is the different phenomenon of illocutionary disablement. Sometimes 'no', when spoken by a woman, does not count as the act of refusal. The hearer fails to recognize the utterance as a refusal; uptake is not secured. In saying 'no' she may well intend to refuse. By saying `no' she intends to prevent sex, but she is far from doing as she intends. Since illocutionary force depends, in part, on uptake being secured, the woman fails to refuse. She is in the position of the actor in Davidson's story, silenced as surely as the actor is silenced. He shouts 'Fire!' He performs the appropriate locutionary act. He means what he says. He intends to warn. He tries to warn. But what he says misfires. Something about him, something about the role he occupies, prevents him from warning the audience. She says 'no'. She performs the appropriate locutionary act. She means what she says. She intends to refuse. She tries to refuse. But what she says misfires. Something about her, something about the role she occupies, prevents her from voicing refusal. Refusal-in that context-has become unspeakable for her. In this case refusal is not simply frustrated but disabled.

Rae Langton. Sexual Solipsism: Philosophical Essays on Pornography and Objectification (Kindle Locations 705-718). Kindle Edition.

Anyway, I apologize for the long quotes and the shallow elaboration, but as I said, I don't have much time at the moment. I may edit this answer and offer more elaborated insights later on.

But just to quickly summarize: I think there is immense value in conceptualizing consent as a Speech Act, with all the implications this entails (e.g. discerning locutionary, illocutionary and perlocutionary aspects), and I recommend thinking deeply about what is it that matters when one gives consent? And from that perspective, are such important aspects hindered when various situations arise? (late consent, revoked consent, misunderstandings about consent, tacit consent, silenced refusal, etc.)

Additional readings I'd recommend to better grasp the subject of consent (or rather, to better understand human intentions and actions, as a foundation for the understanding of consent) would be:

Derek Antony Parfit... was a British philosopher who specialised in personal identity, rationality, and ethics. He is widely considered one of the most important and influential moral philosophers of the late 20th and early 21st centuries

Her monograph Intention (1957) was described by Donald Davidson as "the most important treatment of action since Aristotle."


  • Outstanding contribution to the knowledge base. :D
    – J D
    Mar 11, 2022 at 16:09
  • I really like the way you squared this generally as an issue of perfomativity which is obviously much wider than legality!
    – J D
    Mar 11, 2022 at 16:24

Short Answer

It depends on what you mean by 'consent' and 'invalid', but I'll presume you refer to some generalized notion inherent in the precise definitions of sexual, legal, and informed consent. I think a defensible claim would be that in ethical or moral matters, an adequate type of consent at the time of the event is what matters, but pragmatically, the enforcement of penalties related to consent would be largely a function of the profession of consent during an investigation into the event where evidence of the prior state of consent is lacking.

Long Answer

Consent, like all things volitional, is a tricky business. This is why there is a lot of defining of consent within contexts. In the simplest sense, it just means an activity, as discussed by action theory, was engaged in voluntarily. What does it mean to be voluntary? From WP:

Consent occurs when one person voluntarily agrees to the proposal or desires of another.1 It is a term of common speech, with specific definitions as used in such fields as the law, medicine, research, and sexual relationships. Consent as understood in specific contexts may differ from its everyday meaning. For example, a person with a mental disorder, a low mental age, or under the legal age of sexual consent may willingly engage in a sexual act that still fails to meet the legal threshold for consent as defined by applicable law.

In American criminal law, if an act was perpetrated as a crime replete with mens rea, then changing one's claim that the act was voluntary may not matter. If a witness signs an affidavit or during deposition claims that they were a victim of the crime, and later they recant, ceteris paribus, the affidavit stands as valid under rules evidence and might only be disregarded if coercion can be satisfactorily demonstrated. A witness who changes testimony radically in such a fashion has impeached their credibility. If a witness gives verbal testimony that would be struck as heresay, and then winds up on the stand delivering compelling testimony they consented, then the according to the rules of evidence, the heresay carries no weight, and the witness need not rebut the claims they were coerced. Sexual consent in law is a notoriously sticky wicket.

Informed consent (SEP) is another place where one might see a change in claims from consented to did not consent because of fraud or coercion. Let's say you agreed to inseminated, and then after the fact, you found out it was your doctor's sperm? Does that count as consensual? Many women have claimed no and won settlements. There are different models of consent, depending on a host of factors, with adequate information being one of them. From SEP:

One reason to take non-naturalistic approaches to the status of informed consent seriously is that not all natural rights are legally enforceable. Therefore, a moral informed consent right that is legally enforceable (as that right is usually taken to be in at least some institutional settings) may stand in need of additional moral justification, even if a natural right has been established. That additional, inescapable moral justification may then turn out to justify informed consent regulations even absent natural informed consent rights, say as trust-building measures. In particular, recall that many bioethicists ground informed consent in duties to treat rational, autonomous persons respectfully. Some such duties are clearly non-enforceable. For example, the moral duty not to lie to persons in breach of their autonomous decision-making is seldom legitimately enforceable.

Like all things ethical, and given the defeasibility (SEP) of human reason, it seems it's very hard to build categorical imperatives, regardless of even the effort greatest minds, such as Kant. This is why fora for debating consent, generally legal and ethical, are generally conducted by cased-based reasoning with strong elements of situational ethics dominating the presumptions of the triers of fact.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .