Re: Avicenna's Doctrine of Cerebral Function
L.S., I made a mistake in my reply. The estimative faculty does not CREATE intentions; rather it ASCERTAINS them, but it may make mistakes in this process. For example, in De Anima IV.1, Avicenna writes: ``Moreover, we sometimes make judgements about the objects of perception on the basis of intentions which we do not perceive, either because they are altogether imperceptible thanks to their nature, or because we do not perceive them at the moment when we judge, even though they are perceivable. Those which cannot be perceived thanks to their nature are, for example, the enmity, malice and frightfulness which the sheep apprehends in the form of a wolf and, in short, the intention which makes it flee from it, and the concord which it perceives in its companion and, in short, the intention which causes it to be pleased with it. The sensitive soul perceives these things although the faculty of sense does not teach it anything about them. For this reason the faculty with which these things are perceived is some other faculty, and it is called ``estimation.'' An example of intentions which are perceivable is this: when we see a yellow thing, we may judge that it is honey and sweet. The sensory faculty does not transmit this to the estimation at that moment, even though this belongs to the category of perceived things---although the judgement itself is not perceived in any way. Even though its components belong to the category of that which is perceived, the sensory faculty nevertheless does not apprehend this now. It is only a judgement by which this is assessed, and there may be an error in it; and this, too, belongs to this faculty.'' Avicenna is here talking about what Aristotle called ``perception kata sumbeb`ekos'' (perceiving incidentally), in his On the Soul, III.1 and III.3. As Avicenna (or rather his Latin translators) used the term, an intention is an object of perception, but not necessarily a proper object of any special sense: it may be an object of incidental perception. The best translation of ``intention'' may therefore be: ``object of incidental perception.'' Incidental perception is more prone to error than the perception of proper objects by the special senses is. It is somewhat strange that Avicenna says that intentions (e.g., the enmity of the wolf) are stored in memory. For us, it would seem more natural to say that the belief that the wolf is an enemy, or the belief that wolfs are enemies, is stored there. It seems to be the case that Avicenna did not sufficiently distinguish between the objects of belief, i.e., the things about which we have beliefs, for example, wolfs, and the (propositional) contents of beliefs, e.g., that wolf x is an enemy, or that wolfs are enemies. Aristotle made similar mistakes. Thus, he sometimes says that we may see white things, i.e., individual objects. But he also talks about the perception of whiteness, which is an object of a quite different kind, namely a property. Then again, he may talk about seeing that a certain object is white; this is perception with propositional content. Contemporary philosophers are much more sensitive to these issues, so there does seem to be progress in philosophy after all. I recently read Robert Pasnau's Theories of Cognition in the Later Middle Ages, Cambridge University Press, Cambridge, 1997, but he was disappointingly short on these issues. I hope this helps, too. Dr Gert-Jan C. Lokhorst, Faculty of Philosophy, Erasmus University, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands mailto:lokhorst@fwb.eur.nl http://www.eur.nl/fw/staff/lokhorst/