There is some dispute amongst the Sunni jurists regarding ijma' and qiyas. The Zahirites in particular reject all forms of qiyas and only accept ijma' al-sahaba (consensus of the companions).
Furthermore, he raised the Sunnah to a place of prominence and restricted its legal use. According to al-Shafi'i, only practices directly passed down from Muhammad were valid, eliminating the legitimacy of practices of Muhammad's followers. Prior to al-Shafi'i, legal reasoning included personal reasoning thus suffering from inconsistency.
al-Shafi'i is probably best known for writing Al-Risala, a prime example of applying logic and order to Islamic jurisprudence.
Sunni work Fathul Bari Volume 13 p. 23, Kitab al Ahkam: "If anyone does or says something before Rasulullah(s), and Rasulullah(s) does not stop or rebuke the act/words then this serves a proof as to the permissibility of this act, since Rasulullah(s) was infallible. Others cannot rely on this, as they are not infallible. Imam Bukhari said, other than Rasulullah, the silence of someone cannot be advanced as proof"
Concise Legal Maxims (Qawaid Usuliyah) and their derivatives:
1. Acts are judged by the intention behind them
- a. Leads to presumption of innocence - The norm (of Shari'ah) is that of non-liability of the Muslims unless the opposite emerges.
- b. The norm in regard to things is that of permissibility
2. Certainty is not overruled by doubt
- a. Qati (e.g. Mutawattir) is not over ruled by Zani (e.g. ahad narrations)
3. Hardship begets facility
- a. Necessity makes the unlawful lawful
- b. Necessity is measured in accordance with its true proportions
4. Harm must be eliminated
- a. Prevention of evil takes priority over the attraction of benefit
- b. A specific harm is tolerated in order to prevent a more general one
- c. Harm is eliminated to the extent that is possible
- d. A greater harm is eliminated by means of a lesser harm - e. Harm to an individual is taken in favour of the greater harm
5. Custom is the basis of judgment:
- a. Question and answer proceed on that which is widespread & not on what is unfamiliar.
1. The Basic Asl Refers to the Permissibility of Things
- a. Except for in worship, due to hadith "Any innovation in our matter (worship) which is not a part of it must be rejected.''
- b. No worship can be legislated except by the command of Allah, and no practice can be prohibited except by His prohibition
2. To Make Lawful and to Prohibit Is the Right of Allah Alone
- a. Prohibiting the Halal and Permitting the Haram Is Similar to Committing Shirk
3. The Prohibition of Things Is Due to Their Impurity and Harmfulness
- a. What is Halal Is Sufficient, While What is Haram Is Superfluous
4. Whatever Is leads to the Haram Is Itself Haram
- a. Falsely Representing the Haram as Halal Is Prohibited
5. Good Intentions Do Not Make the Haram Acceptable
- a. The ends does not justify the means
6. Doubtful Things Are To Be Avoided
7. The Haram Is Prohibited to Everyone Alike
8. That which leads to haram is haram
9. That which is necessary to achieve an obligation is obligatory
Profit/Benefit follows responsibility
(A ruling of) Ijtihad is not reversed by its equivalent
Private authority is stronger than public authority
No speech is attributed to one who has remained silent
The Governor will govern in the interests of his subjects
Hudood will not be used when there is doubt.
By default the ordering (amr) text is taken as wajib (prohibiting is taken as haram), and must be done once (sufficient to lift the obligation).
A major/popular/fard issue would have been more famous not remained ahad
When prophet (saw) questioned, this shows the faqih the ilah/cause of a mas-alah.
Anything going in breaks the fast, anything going out breaks wudu.
Usually wudu invalidators will break prayer (exception is laughing).
When there is no room for ijtihad you use the nearest evidence possible
The attachment (alternative) follows the principal(original)
In pure (irrational) ibadah no rationale is used but we follow the texts (shar) only
Analogy cannot be made on exception
In many cases the law in doubtful cases is derived not from substantive principles induced from existing rules, but from procedural presumptions concerning factual probability. An example is the presumption of continuity: if one knows that a given state of affairs, such as ritual purity, existed at some point in the past but one has no evidence one way or the other whether it exists now, one can presume that the situation has not changed. (One can compare, in Western legal systems, the presumption of innocence and the presumption in favour of possession.)