without authorization from revealed law should be no less valid than what they contracted in contravention of revealed law, for in your view the two are equivalent.

We reply: That is not so. A contract they concluded despite its prohibition is deemed valid only if reciprocal delivery followed it. If they embrace Islam before reciprocal delivery, however, the contract is rescinded. By contrast, a contract they concluded without authorization from revealed law is not rescinded, either before or after delivery. I have not seen any jurist of our school or any other school stipulate taking possession in marriage. Rather, they treat conversion to Islam before and after consummation alike, because the marriage contract itself gives rise to legal consequences—such as those of affinity and the like—even when no taking of possession occurs. Likewise, sexual intercourse itself gives rise to legal consequences, even without marriage. Since the marriage contract and sexual intercourse are each intended in themselves—even when one is not joined to the other—the Lawgiver [allowed them] to remain as they were in that regard. This differs from property transactions, whose intended purpose is reciprocal delivery. If reciprocal delivery does not take place, their purpose is not realized; the Lawgiver therefore invalidated them because their intended purpose had not been attained.

This makes clear that the Lawgiver does not nullify the ends people seek through transactions unless He has prohibited them, for He validates such ends only where they are lawful.

Furthermore, when Muslims enter into contracts with one another without knowing whether they are prohibited or permitted, all jurists—so far as I know—deem them valid provided that the parties do not believe them to be prohibited, even though the contracting party did not then know that they were permitted, whether through his own legal reasoning or by following a juristic authority. No one says that a contract is valid only when the contracting party believes that the Lawgiver has permitted it. If the Lawgiver’s specific authorization were a condition for the validity of contracts, no contract would be valid until His authorization had been established—just as a judge who issues a ruling without exercising legal reasoning is sinful, even if his ruling happens to accord with the truth.