Walter Edward Young

The passionate and staunch defence of logic of the controversial thinker Ibn Ḥazm, Abū Muḥammad ʿAlī b. Aḥmad b. Saʿīd of Córdoba (384-456/994-1064), had lasting consequences in the Islamic world. Indeed, his book Facilitating the Understanding of the Rules of Logic and Introduction Thereto, with Common Expressions and Juristic Examples (Kitāb al-Taqrīb li-ḥadd al-manṭiq wa-l-mudkhal ilayhi bi-l-alfāẓ al-ʿāmmiyya wa-l-amthila al-fiqhiyya), composed in 1025-1029, was well known and discussed during and after his time; and it paved the way for the studies of his compatriots Ibn Bājjah (d. 1138), Ibn Ṭufayl (1185), and Ibn Rushd (1198), who each gave demonstrative reasoning a privileged place within the methods of attaining knowledge. Unfortunately, as too often in the history of science, Ibn Ḥazm’s innovative perspectives and contributions in logic have been overlooked or considered with an attitude of contempt. On the one hand, his work has been seen, at best, as promulgating the benefits of studying Aristotle’s logic, so that his contribution is assessed as more didactical than conceptual. And on the other hand, those who do examine his innovations often consider them to be mistaken. As indicated by Chejne (1984, p. 2) contempt towards the logical work of Ibn Ḥazm was also present in its reception by the Eastern philosophers who accused him of deviating from Aristotelian logic and of dabbling in things beyond his capability. However, a reassessment of his work on logic has since begun, by delving into the ways the thinker of Córdoba studied the links between deontic and modal qualification of propositions. In this context Lameer’s (2013) paper on the logical sources of Ibn Ḥazm is worth mentioning; the author (p. 417, footnote 1) observes that, although, strictly speaking, it was al-Fārābī who first drew the parallelism between deontic and modal concepts, it was Ibn Ḥazm who developed it and worked it out in a more precise manner. A primary aim of this paper is to help fill some of these gaps by stressing the role of the work of Ibn Ḥazm in developing a notion of deontic necessity deeply rooted in legal normativity, and in explicitly discussing the transference between deontic and modal concepts. According to our view; the basic units of Islamic deontic logic are what we might call, indulging in terminological anachronism, heteronomous imperatives. As it turns out, the heteronomy of imperatives within Islamic legal systems contrasts with those of the purely moral realm, which seem to be closer to an autonomous conception of moral law. There it concurs again with Leibniz’s proposal to define obligatory as “what is necessary for a good person to do”. In the present paper, we will focus on the heteronomous imperatives of legal systems rather than on the imperatives of the purely moral realm. In this context, the work of Ibn Ḥazm extends the parallelism between the necessity of events and that of human actions stressed by his predecessors. According to our understanding, Ibn Ḥazm’s parallelism can be rendered explicit formally by means of a conditional (or hypothetical) structure shared by both deontic and modal propositions. Moreover, this structure makes apparent that this parallelism displays an underlying system of “degrees”. Indeed, while in the domain of events, given some conditions, it makes sense to distinguish between an event that is more likely to happen than another. Ibn Ḥazm speaks of near and distant possibility (such as the higher degree of likelihood of rain, given the condensation of clouds in December, and its lower degree, when the condensation occurs in summer); and, in the domain of actions, the Islamic notion of weighting actions determines degrees of virtue (or of legal and moral value). So whereas the degree of virtue of performing a forbidden act as determined by the distribution of sanction and reward is 0, we obtain the same value by pondering the likelihood of an impossible event to take place. Furthermore, as discussed in section II.3.2, the system of values at work in the parallelism can be seen as opening the way to a more direct correspondence. Thus, while in the realm of nature, likelihood of occurrence of an event is dependent upon the conditions specific to the occurrence of that event; while, in the realm of jurisprudence, likelihood of performing an action is dependent upon the distribution of reward and sanction specific to that action (being that, given the choice to perform or not perform a given action, those that will be rewarded are more likely to be performed than those that are not). According to this perspective, the point of the parallelism is that both deontic and modal qualifications measure the degree of an action or event to become actual; that is – indulging once more in anachronism (but this time from the Leibnizian background) – the degree measures how feasible (facile) an action or event may be. This suggests that Ibn Ḥazm’s perspectives already herald the links to probability and possibility explored by Leibniz six centuries later – see for example Leibniz’s (1671, A VI, I, p. 424-26) use of probability in the context of conditional right. Nevertheless, it also shows a crucial difference to the approach developed in the Elementa Jura Naturalis: whereas Leibniz’s studies seek to define what is to be just or virtuous, the logical system of deontic imperatives within Islamic jurisprudence presupposes that what is to be virtuous has already been settled. Determining what is to be virtuous is not achieved by logical reasoning within the system of legal jurisprudence, but by delving into the higher objectives of the Sharīʿa. While developing our point, we will delve into the logical structure of the heteronomous imperatives. This distinguishes our contribution from the existing literature, such as the papers of Chejne (1984), Lameer (2014), and Guerrero (1997, 2010, 2014), which do not provide a logical analysis of the deontic concepts put into work by Ibn Ḥazm. The true antecedent to the present paper is the work of Farid Zidani (2007, 2015), who, so far as we know, was the first to undertake such a task. Some of our own developments and general epistemological thoughts go beyond Ibn Ḥazm’s framework and motivations; mainly those contained in sections II.3.2 and IV. However, according to our view, these reflections suggest that Ibn Ḥazm’s approach has the substance for a broader and deeper exploration of the logic of norms. The paper is structured as follows:I.Ibn Ḥazm’s Logic of Heteronomous Imperatives. After presenting some extracts of the relevant text, we proceed by providing a formal reconstruction of the five forms of deontic modalities. II. A Landmark in the History of the Logical Analysis of Norms. Duties and Modalities. In this section, we study the transferences from deontic to modal necessity and possibility. We briefly compare the deontic system of Islamic Jurisprudence with that of Leibniz.III. Leibniz and Hypothetical Imperatives in Law.IV. Beyond Ibn Ḥazm: Conclusions and the Work Ahead. We will conclude the paper by discussing briefly some conceptual points that distinguish the logic of heteronomous imperatives from contemporary deontic logic. Our final words will discuss deontic-modal parallelism in the context of Ibn Ḥazm’s rejection of reasoning by conjecture and what we call “the internalization of nature.”.

The Dialectical Forge identifies dialectical disputation as a primary formative dynamic in the evolution of pre-modern Islamic legal systems, promoting dialectic from relative obscurity to a more appropriate position at the forefront of Islamic legal studies. The author introduces and develops a dialectics-based analytical method for the study of pre-modern Islamic legal argumentation, examines parallels and divergences between Aristotelian dialectic and early juridical jadal-theory, and proposes a multi-component paradigm—the Dialectical Forge Model—to account for the power of jadal in shaping Islamic law and legal theory.In addition to overviews of current evolutionary narratives for Islamic legal theory and dialectic, and expositions on key texts, this work shines an analytical light upon the considerably sophisticated “proto-system” of juridical dialectical teaching and practice evident in Islam’s second century, several generations before the first “full-system” treatises of legal and dialectical theory were composed. This proto-system is revealed from analyses of dialectical sequences in the 2nd/8th century Kitāb Ikhtilāf al-ʿIrāqiyyīn / ʿIrāqiyyayn through a lens molded from 5th/11th century jadal-theory treatises. Specific features thus uncovered inform the elaboration of a Dialectical Forge Model, whose more general components and functions are explored in closing chapters.

The post-classical (or post-Avicennan, post-Rāzian) genre of the “protocols for dialectical inquiry and disputation” ( _ ādāb al-baḥth wa-l-munāẓara _ ) has its more proximate origins in the famed _ Risāla _ of Shams al-Dīn al-Samarqandī (d. 722/1322). The greater part of his conceptions and methodology, however, consists in a streamlining and universalizing of the more strictly juristic dialectic ( _ jadal _ / _ khilāf _ ) of his teacher Burhān al-Dīn al-Nasafī (d. 687/1288); and this in turn draws on the highly logicized dialectic of Rukn al-Dīn al-ʿAmīdī (d. 615/1218) and his teacher Raḍī al-Dīn al-Nīsābūrī (d. 617/1220). At the heart of methods in this lineage, and carried forward by al-Samarqandī into the universal _ ādāb al-baḥth _, are three truth-preserving logical relationships critical to the truth-seeking enterprise of dialectic: entailment ( _ talāzum _ / _ mulāzama _ ), mutual negation or exclusion ( _ tanāfin _ / _ munāfā _ ), and causal concomitance ( _ dawarān _ ). The practical elaboration of these relations reveal...

The post-classical genre of the “protocols for dialectical inquiry and disputation” has its more proximate origins in the famed Risāla of Shams al-Dīn al-Samarqandī. The greater part of his conceptions and methodology, however, consists in a streamlining and universalizing of the more strictly juristic dialectic of his teacher Burhān al-Dīn al-Nasafī ; and this in turn draws on the highly logicized dialectic of Rukn al-Dīn al-ʿAmīdī and his teacher Raḍī al-Dīn al-Nīsābūrī. At the heart of methods in this lineage, and carried forward by al-Samarqandī into the universal ādāb al-baḥth, are three truth-preserving logical relationships critical to the truth-seeking enterprise of dialectic: entailment, mutual negation or exclusion, and causal concomitance. The practical elaboration of these relations reveals a logic in action—a premodern dialogical logic for living disputation praxis. In fact, so critical were these to the dialectical enterprise that al-Samarqandī devoted a specialized treatise entirely to summarizing their defining features and rules, aptly naming it the ʿAyn al-Naẓar, or “Wellspring of Rational Investigation.” In this article, and drawing upon a recently published digital critical edition, I will present an analytical outline of these core logical relations as presented in the ʿAyn al-Naẓar. Then I will address a number of points of interest in this text, grouped under six themes: the potential for cross-disciplinary advancement; notions in discursive development; significant or uniquely contributive formulations; peculiarities of content; signs of an evolving, universalist agenda; and evidence that the ʿAyn al-Naẓar was designed as an aide-mémoire for the active disputant.

Qiyās, or “correlational inference” (often glossed as “analogy”), comprises a primary set of methodological tools recognized by a majority of premodern Sunnī jurists. Its elements, valid modes, and proper applications were the focus of continual argument and refinement. A particular area of debate was the methodology of determining or justifying the ʿilla: the legal cause (or occasioning factor, or ratio legis) giving rise to a ruling in God’s Law. This was most often discussed (and disputed) under the rubric of “the modes of causal justification” (masālik al-taʿlīl). Among these modes was the much debated test of dawarān (concomitance of presumed cause and effect). In brief, proponents of dawarān employed it to justify claims that a property (waṣf) occasioned the ruling (ḥukm) in an authoritative source-case (aṣl). In concert with other considerations, the demonstrated co-presence (ṭard) and co-absence (ʿaks) of property and ruling—that is, their concomitance “in existence” (wujūdan) and “in nonexistence” (ʿadaman)— was taken as an indication that the property was the ruling’s ʿilla. Delving further into dawarān and causation (ʿilliyya), the current study interprets “in existence” and “in nonexistence” not as a kind of metaphor for true and false (within the framework of a classical truth-functional formal semantics), but as an accurate terminology vis-à-vis the meaning of causality statements, fully compatible with dominant Islamicate views on causal agency. In brief, a deeper logical and linguistic analysis of the different existential modes of dawarān strongly suggests that we should distinguish property (or phenomenon) and ruling (or effect) as types (concepts or propositions linguistically expressed by a sentence) as opposed to tokens (instantiations of the type; the real, ontological events that verify the proposition). Our reading of dawarān as shaped by a finer-grained structure not only allows us to identify the efficient occasioning process as a function which takes some particular token of the ʿilla (arguably, the property or properties which provide the ruling’s material cause) and renders a token of the general ruling type, but it allows us to elucidate the role of taʿlīl (causal justification) in shaping an epistemological theory of argument to the best explanation: a sophisticated, premodern manifestation of abductive reasoning.