Article 1331. In order that mistake may invalidate consent, it should refer to the substance of the thing which is the object of the contract, or to those conditions which have principally moved one or both parties to enter into the contract.
Mistake as to the identity or qualifications of one of the parties will vitiate consent only when such identity or qualifications have been the principal cause of the contract.
A simple mistake of account shall give rise to its correction.
Artikulo 1331. Upang ang pagkakamali ay mapawalang-bisa ng pahintulot, ito ay dapat sumangguni sa mga sangkap ng mga bagay na kung saan ang bagay sa kontrata, o kaya sa mga kondisyon na kung saan inilipat ang isa o ang parehong partido na pumasok sa kontrata.
Ang pagkakamali sa pagkakakilalan o kalidad ng isa sa mga partido ay mapapawalanng bisa ang pahintulot kapag ang pagkakakilanlan o mga kwalipikasyon ang pangunahing sanhi ng kontrata.
Ang isang simpleng pagkakamali ang syang magpapataas sa pagwawasto.
Mistake or error is the false notion of a thing or a fact material to the contract.
NATURE OF MISTAKE
(1) Mistake may be of fact or of law. In general, the mistake to which Article 1331 refers is mistake of fact. It may arise from ignorance or lack of knowledge.
(2) The mistake contemplated by law is substantial mistake of fact, that is, the party would not have given his consent had he known of the mistake. Hence, not every mistake will vitiate consent and make a contract voidable.
MISTAKE OF FACT TO WHICH LAW REFERS
In order that mistake may vitiate consent, it must refer to:
(1) the substance of the thing which is the object of the contract; or
(2) those conditions which have principally moved one or both parties to enter into the contract; or
(3) the identity or qualifications of one of the parties, provided, the same was the principal cause of the contract.
No. 1 above includes mistake regarding the nature of the contract, as when the contracting parties believe that the other is selling, when in truth and in fact, both are buying.
MISTAKE OF FACT WHICH DOES NOT VITIATE CONSENT
(1) Error as regards the incidents of a thing or accidental qualities thereof (e.g., accessibility of a residential house to means of transportation; maximum speed of a car), not taken as the principal consideration of the contract, does not vitiate consent (Art. 1331, par. 1.), unless the error is caused by fraud of the other party.
(2) Mistake as to quantity or amount does not also vitiate consent but only gives rise to its correction, unless it goes to the essence of the contract.
(3) Error as regards the motives of the contract does not also vitiate consent unless the motives constitute a condition or cause of the contract.
(4) Mistake as regards the identity or qualifications of a party does not vitiate consent for the reason that contracts are entered into more in consideration of the things or services which form their subject matter rather than of persons. The exception is when such identity or qualifications have been the principal cause of the contract (Art. 1331, par. 2.), as in contracts, which have for their object obligations to do, requiring personal qualifications of the debtor, or involving trust and confidence, such as contracts of partnership, agency, commodatum, guaranty deposit, etc.
(5) Error which could have been avoided by the party alleging it, or which refers to a fact known to him, or which he should have known by the exercise of ordinary diligence, or which is so patent and obvious that nobody could have made it, will not invalidate consent.
EXAMPLES
(1) Mistake regarding object. —
Ben is buying from Sarah a breeding cow but Sarah is selling a barren cow.
(2) Mistake regarding condition of the contract. —
Sarah is selling his parcel of land for P100,000.00 cash but Ben is buying the land thinking that the price is payable in installments.
(3) Mistake regarding identity or qualifications. —
(a) Sarah sold his car to Ben. Sarah thought that Ben, who is a lawyer, was a doctor. The mistake here is not material as to avoid the contract.
(b) Ryan donated his car to Ena. Ryan thought that Ena was his half-sister. It turned out that Ena is not related to Ryan. The mistake as to the identity of Ena in this case is material because his identity was the principal reason or consideration for the donation.
OBLIGATIONS AND CONTRACTS 