THE ARGUMENT FROM IGNORANCE AND ITS CRITICS IN MEDIEVAL ARABIC THOUGHT AYMAN SHIHADEH SOAS, University of London, Russell Square, London WC1H 0XG, UK Email: a.shihadeh@soas.ac.uk Abstract. The earliest debate on the argument from ignorance emerged in Islamic rational theology around the fourth/tenth century, approximately seven centuries before John Locke identified it as a distinct type of argument. The most influential defences of the epistemological principle that ‘that for which there is no evidence must be negated’ are encountered in Muʿtazilī sources, particularly ʿAbd al-Jabbār and al-Malāh ˙ imī who argue that without this principle scepticism will follow. The principle was defended on different grounds by some earlier Ashʿarīs, but was then rejected by al-Juwaynī, and was eventually classed as a fallacy by Fakhr al-Dīn al- Rāzī whose Nihāyat al-ʿuqūl contains the most definitive and comprehensive refu- tation of classical kalām epistemology and the first ever defence of Aristotelian logic in a kalām summa. According to the eighth/fourteenth-century historian Ibn Khaldūn, this debate provided the main impetus for the philosophical turn that Ashʿarism took during the sixth/twelfth century. Résumé. La plus ancienne discussion concernant l’argument d’ignorance est attestée dans la théologie rationnelle islamique aux environs du IV e /X e siècle, quelque sept siècles avant que John Locke l’identifie comme un type distinct d’argument. Les défenses les plus influentes du principe épistémologique suivant lequel ‘ce dont il n’y a aucune preuve doit être nié’ se rencontrent dans des sources muʿtazilites, en par- ticulier chez ʿAbd al-Jabbār et al-Malāh ˙ imī, qui soutiennent que, sans ce principe, on tombe dans le sceptisme. Ce principe a été défendu sur la base d’arguments différents par certains Ashʿarites antérieurs, mais a été ensuite rejeté par al-Juwaynī, avant d’être finalement catégorisé comme un sophisme par Fakhr al-Dīn al-Rāzī, dont les Nihāyat al-ʿuqūl offrent la réfutation la plus systématique – et définitive – de l’épistémologie du kalām traditionnel et la toute première défense de la logique aristotélicienne jamais développée dans une somme de kalām. Enfin, selon l’historien du VIII e /XIV e siècle Ibn Khaldūn, c’est cette discussion qui donna la principale impul- sion au tournant philosophique pris par l’Ashʿarisme au cours du VI e /XII e siècle. In modern philosophy and logic, the argument from ignorance (or the appeal to ignorance, or the argumentum ad ignorantiam) was first identified as a distinct type of argument in the late seventeenth century by John Locke, who viewed it as a suspicious form of reasoning. 1 It later 1 John Locke, An Essay Concerning Human Understanding (1690), ed. John W. Yolton (London, 1961), 4.17.20; cf. H. Vilhelm Hansen, ‘Locke and Whately on the Argumentum ad Ignorantiam’, Philosophy and Rhetoric, 31.1 (1998): 55–63. On the argument from Arabic Sciences and Philosophy, vol. 23 (2013) pp. 171–220 doi:10.1017/S0957423913000027 © 2013 Cambridge University Press