What does mean by Aql & Qiyas in Islam?

Aql in Islam

Islamic Scholars attaches great importance to the principle of ‘Aql (reasoning) for a number of reasons. The Holy Quran urges Believers to strive to develop an understanding of religion as well as worldly matters. The Quran mentions itself as a Book of Wisdom in many places. For example:

These are the verses of the Book of Wisdom (10:1).

Then, the Holy Quran invites mankind to develop wisdom by closely observing various objects and phenomena of Nature. It says:

Do they not travel through the land, so that their hearts (and minds) may thus learn wisdom (22:46).

For the Shia’ Mujtahid, every new and challenging situation should be analysed and examined in a rational manner. Thus, the use of wisdom, reasoning or ‘Aql occupies an important place in the legal thinking of the Shia’ community.

What is Qiyas

Qiyas is the fourth and most dependent source of Islamic Law. Literally, Qiyas means measuring or comparing with or judging by comparing. In Islamic Jurisprudence (Shariah), Qiyas is a process of deduction by which the law of text (Nas) is applied to cases that have not been clearly covered by the other sources of Islamic Law.

In the Quran, we find a number of verses where Allah Almighty has enjoined us to use our brains and reasoning.

For instance, in 59:2 the Quran asks us to utilize our insight in order to learn lessons:

Then take admonition O you with insight.