Chapter V: On Aleatory Contracts

593. Essentially aleatory contracts, so called from alea, that is, an uncertain event, on which they essentially depend, for in other contracts also there can be an alea, are those by which uncertain gain is sought or uncertain damage is averted by a certain price given (a. 1964). This uncertainty of gain or damage must not only be on the part of both contracting parties, but also must be almost equal; otherwise injustice is committed. Hence, that they may be lawful, it is required: 1. that the alea be morally equal; 2. that no fraud be present; 3. nor any scandal or prohibition of positive law.

An aleatory contract can be diverse:

A. On the part of the uncertainty of the thing to be furnished; according as a) it is uncertain from one part only, as in insurance, in which one pays a certain thing while the other is obliged to repair an uncertain damage; or b) it is uncertain from each part, as in play and wagering.

From this it is understood that an aleatory contract differs much from a conditioned contract entered into under a suspensive condition: for the latter does not exist unless the condition has been fulfilled; the former is firm and absolute, but it remains uncertain only whether or which of the contracting parties ought to furnish something.

B. On the part of the object; which can be 1. uncertain damage to be guarded against, as in insurance; or 2. uncertain gain to be obtained, as in lottery and gratuitous play; or 3. gain or damage, whether a) determined by an unknown event, as in wagering, or by a future event, as in onerous play; or b) indeterminate, as in Stock Exchange speculations.

We shall speak:

1. Of insurance.

2. Of play, wagering, and lottery.

3. Of Stock Exchange speculations.