In the Name of Allah, the Most Compassionate, the Most Merciful.

All praise is due to Allah alone, and may blessings and peace be upon the one after whom there is no prophet.

To proceed:

This is a concise and useful outline of uṣūl al-fiqh (the foundational principles of jurisprudence). My purpose is to set forth the elementary notions of this important science—one that every student of the Quran and the Prophetic Sunnah, everyone who seeks to uncover their meanings and derive their issues and rulings, must know. I have culled it from several standard works on uṣūl, selecting and refining the material so that it may be simple and accessible. I ask Allah, exalted is He, for help and success.

Knowledge

Knowledge is to comprehend a thing as it truly is, insofar as it is something that can be known. It is of two kinds:

1. Necessary knowledge: knowledge that attaches to a person in such a manner that he cannot repel it from himself; it does not arise from reflection or inference. This includes that which is acquired through the five senses.

2. Acquired knowledge: knowledge obtained through deliberation and reasoning, such as knowing that the prayer and zakāh are obligatory and other matters that require investigation and proof.

Ignorance

Ignorance is to conceive of a thing contrary to what it actually is, and it is of two types:

1. Simple ignorance: the complete absence of any perception of a matter that can in fact be known.

2. Compound ignorance: a firm conviction that does not correspond to reality. It is called “compound” because its possessor is ignorant of the ruling and ignorant of his own ignorance.

Degrees of Perception

1. Certainty: the heart’s firm conviction supported by evidence.