Can you please explain these terms and their significance
First of all, it should remain clear that these terms are not terms of the Shari`ah nor should these be considered as sources of Islam. These terms relate to propounded principles of legislation in a Muslim state or principles ofIjtehad, for Muslim scholars. These principles relate to common sense and are not based on any express directives of the Shari`ah. The referred terms are briefly explained below:
Al-Masalih al-Mursalah (المصالح المرسلة), is also known by some as Argumentation through al-Mursal and by others as merely Argumentation.
According to Khwarzamiy, Maslihah implies to make laws, in matters for which the Shari`ah has not made any express prescriptions, in such a manner that the purpose entailed in the laws of the Shari`ah are safeguarded, inasmuch as the subjects for whom the laws are being made are saved from harm. According to Ghazali, it relates to the making appropriate laws, on the basis of the appropriate meaning derived logically through the understanding of the purpose of the Shari`ah, for matters on which the Shari`ah has not given any express directives. According to Ibn Burhan, it relates to matters which are not, fully or partly, expressly prescribed by the Shari`ah.
In other words, Al-Masalih al-Mursalah, is a propounded principle of legislation according to which, in all such matters about which the Shari`ah has not made an express prescription, laws should be proposed and implemented with a view to the general well being of the people and with a view to safeguarding them from any potential harm.
Al-`urf (العرف), in simple words, is what we know as ‘tradition’ or ‘general custom’. It is generally defined as that custom which people consciously abide by and which is generally accepted by them.
According to the Muslim scholars of the science of legislation, in the absence of an express directive of the Shari`ah, `urf serves is a binding standard of acceptable behavior.
Al-Istihsaan (الإستحسان), in simple words, implies to prefer one opinion over another on the basis of one’s finding it to be more appropriate.
I hope this helps.
August 29, 2003