admit alternative interpretation, as with an effective cause identified by inference and supported by demonstrated effect, such as the intoxicating property of wine. Since prohibition is present when this property is present and ceases when it ceases, this indicates that it is the effective cause. Yet this cannot be affirmed with certainty, for Abū Hanīfa maintains that wine is prohibited because of its name. This is a possible explanation, since the name applies when the intoxicating property is present and ceases to apply when it is absent.

Another example is the effective cause of ribā, concerning which the jurists have differed, as they have concerning its attributes and conditions. Many Mālikīs hold that it consists in articles of the same kind being edible, storable, and either staple foods or substances used to improve staple foods. Some add the qualification that they generally constitute a mainstay of subsistence. Many Shāfiʿīs hold that edibility alone is the effective cause, to the extent that they prohibit exchanging unequal quantities of scammony or Armenian clay. The Hanafīs hold that the effective cause is measurement by volume or weight.

Each of these jurists considers his own effective cause more likely to be correct than that proposed by another. Yet none knows with certainty that it is the effective cause, nor claims to possess an explicit text establishing it from the Book or the Sunnah, or an implicit indication equivalent to an explicit text. Rather, his evidence for it is his predominant belief that it is correct. Thus, the effective cause is probable, whereas the obligation to rule on its basis, when its correctness is considered most likely, is known with certainty. This type of analogy is subtle analogy. Likewise, an effective cause explicitly stated in the Sunnah is also probable when the text establishing it is transmitted through solitary reports, although ruling on its basis is known to be required.

An illustration of what we have mentioned and explained is the testimony of two witnesses. Their uprightness is not known with certainty; rather, they are deemed upright on the basis of predominant belief. Once the judge considers it most likely that the two witnesses are upright, the requirement to rule on that basis is known with certainty.

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Everyone who reasons by analogy brings one known case under the same ruling as another on the basis of a meaning common to both. They have said that analogy is of three kinds: analogy based on an effective cause, analogy by indication, and analogy based on resemblance. Examples of analogy based on an effective cause include drawing an analogy between rice and wheat, between nabīdh and wine, and between eating during Ramadan