There’s something very odd about the phrase “consenting adults”.

Once, I think, it meant something like this: acts performed in private by consenting adults, which cause harm to no one else, are nobody’s business except that of the two adults involved. As a legal standard of when the state is entitled to interfere, this makes a great deal of sense—at least, to a certain extent. I’m minded of the affair some years ago when a German citizen advertised on the Internet for a person willing to be slaughtered and eaten, and got one. Apparently these were consenting adults, but this, for which God and good sense be praised, did not prevent the cannibal from being arrested, tried, and convicted, though too late to save his victim.

But these days, the phrase “consenting adults” seems to be used in ordinary speech as a moral rather than a legal standard. If it’s between consenting adults, it’s OK. Not only is the state not entitled to interfere, other observers are not entitled to disapprove on moral grounds. The attention has shifted from the particular act, performed in private, to the kind of act as discussed in public. Who are you to tell me that I shouldn’t sleep with whoever I like? We’re consenting adults.

And yet consent is no kind of moral stamp. On the contrary: far from being a precondition for morality, consent is a necessary precondition for sin. The sin lies, in fact, in my giving my consent to my sinful act. Imagine this dialog:

“I would like to sin with you. Will you sin with me? I think we will both enjoy it.”

“Yes, please, I would very much like to sin with you. Shall we do it now?”

Here we have consenting adults, agreeing quite knowledgeably that they are about to do wrong, and voluntarily choosing it. Where’s the morality in that? And yet people still trot out “consenting adults” as a reason for withholding moral censure.

There’s a related rhetorical move: the assumption that any statement of moral censure implies a desire on the part of the speaker to make the censured behavior illegal. But that’s another post.