The principle of consistency in contractual matters.

Summary The principle of coherence stigmatizes contradiction and tends to restore coherence to a contradictory act or inconsistent behavior. A large part of the rules of contract interpretation revolves around the restoration of coherence to the commitment. Moreover, the insidious contradiction consisting in << committing oneself without committing oneself>> is stigmatized by article 1174 of the Civil Code. Beyond the Civil Code itself, the notion of essential obligation seems to be no more than a mask for the principle of coherence, prohibiting a party from emptying the promise of its substance by the stipulation of a clause <>. The same is true when the debtor attempts to deprive his promise of any binding character by adding a <>. The principle of coherence then authorizes the judge to deprive the contradictory reservation of the purpose of the document of effect. The principle of coherence also manifests itself in the guise of a duty imposing stability of conduct. It provides the criteria for understanding contradiction and seems to be able to account for the regime of withdrawal from the offer, tacit waiver, unfair termination of contracts with successive performance or the impossibility of suddenly invoking the resolutory clause. In a similar way, the author of a conduct which has induced third parties to draw consequences cannot adopt a reverse party under the sole pretext of his changing interests. Thus, one can discern a tendency in the case law to regard contradictory reversal as ineffective, leaving the effects of the initial manifestation of will intact. The sanction is the same when the debtor or the creditor obstruct the performance of the agreement which they themselves have entered into. The principle of coherence thus makes it possible to moralise behaviour, while preserving legal certainty.