In general the law presumes that all natural persons are capable of entering into a contract. Inability to contract is the exceptional, and not the natural condition. The burden of proof is on the party who alleges the lack of capacity to contract. The following class of persons lack the power of contracting, either in whole or in part:

Minors.1

Married women.2

Persons of unsound mind.3

Drunken persons.4

Spendthrifts, for whom guardians or conservators have been appointed.5

Aliens.6

Contracts may be entered into not only by natural, but also under certain restrictions by those artificial persons created by the law, and known as corporations.7 Finally, a person either natural or artificial may make contracts not only for himself, but also in relation to a fiduciary position which he holds towards another.8