Position of Good Faith in the Twelver Shia jurisprudence

Good faith means doing duties honestly, fairly and logically, duties which two parties of the contract or other contract related third parties expect them from one another. Meta jurisprudential conceptions such as sincerity, justice, fairness and some jurisprudential rules such as irrevocability of contracts, prohibition of causing loss and damage, benefaction and principle of validity are the origins of the principle of good faith in Islamic resources. Therefore, the divine legislator presumes the principle of validity and considering Muslims behavior as valid, a point mentioned and emphasized in the Quran. This rule sometimes functions negatively to express the instances of good faith such as forbidding people from deceiving others. So, with regard to the point that Imamiyyah jurisprudence is the original resource of Iranian law, the legislator can, by inspiring from moral and jurisprudential teachings, legislate the principle of good faith. In this article, some of approaches to good faith in sale contract and contract of mandate will be briefly studied.