you draw an analogy with it, that the effective cause underlying the ruling in the original case must also be present in the new case. Why, then, do you say that the effective cause in the original case is mere nonexistence? Why could it not instead be selling something while it does not exist when its sale could be postponed until it exists? On this understanding, the effective cause is restricted to a particular kind of nonexistence: that of something which can be sold after it comes into existence. Unless you establish that the effective cause in the original case is the feature shared by both cases, your analogy is unsound. This demand for proof is sufficient to halt your analogy.

But we can also demonstrate its invalidity as follows: the cause we have identified applies consistently, whereas the cause you have identified admits of counterexamples. If you explain the prohibition by mere nonexistence, certain assets and usufructs invalidate your proposed cause. But if you explain it by the nonexistence of something whose sale can be postponed until it exists, or by nonexistence involving uncertainty, the cause applies consistently. Moreover, this cause is supported by its suitability to the ruling.

For if something has both a state of existence and a state of nonexistence, selling it while nonexistent involves risk and gambling. This is the reason the Prophet, peace and blessings be upon him, gave for the prohibition when he said:

‘Tell me: if Allah withholds the fruit, on what grounds does any one of you take his brother’s wealth without right?’

This is unlike something that has only one state and is ordinarily free from harm: this does not involve risk, and there is a need for it. One of the principles of Islamic law is that when benefit and harm conflict, whichever outweighs the other takes precedence. He prohibited sales involving uncertainty only because they involve risk that harms one of the two parties, whereas in