Point III. On the Effects of a Contract for a Cause

I. Notion. A contract for a cause is had when in the contract there is expressed the motive on account of which it is entered into, for example: I give this to you because you have done this or that for me.

II. Validity. 1. If the sole or principal cause does not subsist, the contract is invalid. The reason is that substantial error is had; in other words, the object of consent, for example a donation as remuneratory or as alms, is different from the object of the present contract, for example a donation which is not remuneratory or alms, or at least consent is attached to the sole or principal cause.

2. If a secondary cause does not subsist, this must be said: if it did not give cause to the contract, the contract is valid and non-rescindable; and this holds even if the error was induced by fraud and by the other contracting party. If it gave cause to the contract, and was induced by fraud by the other contracting party, the contract is valid, but rescindable (n. 837).

III. The effect or obligation is easily drawn out from what has been said.