Disclaimer: Being neither a legal philosopher nor a lawyer, I ask that the following be taken with a grain of salt.
Start with this argument as background:
- There is never an on-balance reason to do something immoral.
- It is immoral to press someone to do something immoral.
- Therefore, there is never an on-balance reason to press someone to do something immoral.
Now, add this observation:
- Enforcing a contract is at least partly constituted by pressing the parties to perform the contracted action.
Finally, let us add a very weak and uncontroversial liberal premise:
- The exertion of pressure by the state on a citizen is only permissible given an on-balance reason to exert that pressure.
It follows from (1)-(5) that
- It is not permissible for the state to enforce a performance-immoral contract.
This doctrine of the unenforceability of performance-immoral contracts would have some interesting and far-reaching consequences. For instance, if you're a pornographer, many of your contracts would end up being unenforceable. This would not destroy the pornography industry, but would make it significantly harder for larger pornographic businesses to operate. (That said, despite the value of small businesses, I do not know whether small pornographic businesses are preferable to large ones.)
Another interesting consequence of the argument would be the conditional that if same-sex sexual activity (SSSA) is immoral, then the state is not permitted to recognize a same-sex marriage (SSM). For a marriage is, among other things, an agreement to engage in a shared life of a sexual nature.[note 1] But if SSSA is immoral, then to engage in a shared life of a sexual nature with someone of the same sex is immoral. And for the state to recognize a contract always involves a measure of enforcement at least by means of public opinion. Thus, the recognition of a SSM would be an enforcement of a performance-immoral contract, and that is not permissible to the state. Of course, this is all predicated on the assumption that SSSA is immoral, an assumption that the proponents of SSM will not grant. However, the conditional that if SSSA is immoral, then SSM ought not be recognized is itself an interesting conclusion, since people like John Rajczi have argued that even if SSSA were immoral, the state ought to recognize SSMs.
I think the best way to challenge my argument is to challenge the conjunction of (3) and (4) by using Double Effect kind of reasoning. The pressure in (3) is either intended or not. If the pressure in (3) is not intended, then (3) is false. For it is permissible to do things that put pressure on others to act immorally, if the pressure is not intended to do that. For instance, by asking someone to whom we've lent money for our money back, which we may well have a right to do, we might put some pressure on them to steal the money. So the pressure in (3) must be intentional. But then for the validity of the argument, the pressure in (4) must also be intentional. However, one might argue that the state's enforcement of contracts is not intended to press for performance. It is, instead, intended to press for the disjunctive state of affairs of performance or compensation.
I am not sure about this response. But it does seem that if we agree with this, then we should distinguish, strictly speaking, the state's recognition of a contract from the state's enforcement of it. The enforcement consists, then, in pressing for performance or compensation. But the recognition presses by means of public opinion—contract-breakers are not well thought of—for performance. There is, I think, some reason to distinguish recognition from enforcement. We should not recognize a contract with a graphic designer to draw a square circle—the contract is null and void on grounds of impossibility. However, we could press for performance or compensation. If this is right, then the argument would show not that it is wrong for the state to enforce a performance-immoral contract, but that it is wrong for the state to recognize one.
Thus the state could still enforce contracts between pornographers and their printing or DVD pressing shops, without recognizing these contracts. However, if SSSA is immoral, the state still could not recognize SSM, though it could enforce marriage-like contracts between persons of the same sex. But by calling it a marriage, it would be recognizing such contracts, and this the state has no right to do if the contracts are performance-immoral. This could make it possible for one to have a principled reason to disallow SSM while allowing the state to enforce the contractual aspects of "same-sex unions". (This post is also an experiment: will everyone be put to sleep by the stuff on contracts before they get to the sex stuff.)