302 THE REASONING OF INDIVIDUAL IRAQIANS

Tr. IX, 6: Abū Yūsuf adduces traditions against Auzāʿī but does not follow them himself in all their implications, and Shāfiʿī blames him for this.

Tr. IX, 16 f.: Abū Yūsuf is bound by traditions more than Auzāʿī, though less than Shāfiʿī (above, p. 278), but he combines this with competent systematic reasoning.

Tr. IX, 34: On account of traditions which Abū Ḥanīfa had disregarded, Abū Yūsuf reverts to Auzāʿī's doctrine; he also refers to a tradition in order to excuse Abū Ḥanīfa's systematic doctrine (above, p. 287). In § 36, under the influence of historical traditions, Abū Yūsuf again falls back on the doctrine of Auzāʿī. In §§ 36 and 37, Abū Yūsuf mistakenly seeks to find a justification in traditions for the doctrine held by Abū Ḥanīfa on the basis of systematic reasoning.

Tr. IX, 38: Here, for once, Abū Yūsuf gives sound systematic reasoning which causes him to reject a tradition as irregular, applying a method which he himself set out in detail in § 5.

Kharāj, 36: Whilst himself diverging from Abū Ḥanīfa's doctrine, Abū Yūsuf defends him against the charge of disregarding traditions.

Kharāj, 126 f.: In this later parallel to the earlier passage Tr. IX, 22, Abū Yūsuf, though holding essentially the same doctrine, shows himself less systematic in his reasoning and more bound by traditions.

Compared with this increasing dependence on traditions, other kinds of material considerations are less prominent in Abū Yūsuf's doctrine. His legal reasoning is, generally speaking, of the same kind as that of his predecessors.

The new features which we can discern in Abū Yūsuf's legal thought are certain favourite processes of reasoning, and a habit of rather acrimonious polemics.

The reductio ad absurdum was used in discussions well before Abū Yūsuf, but Abū Yūsuf made it a favourite method of his.¹ It is connected with the reasoning from extreme and border-line cases, a kind of argument which had been extensively used by Abū Ḥanīfa before Abū Yūsuf adopted it.² An example typical of Abū Yūsuf occurs in Tr. IX, 33, where he tries to support Abū Ḥanīfa's excellent systematic reason with fictitious border-line cases which are not all happily chosen.

Another of Abū Yūsuf's favourite lines of attack against other opinions is to point out their inconsistency.³ This presupposes a respectable standard of systematic reasoning on his part. He further