Avicenna's Predications of Animals

Avicenna observes that all predications can be taken in two ways, either essentially or under a certain description. For instance, it is essentially true of humans that they can laugh, but if we stipulate that a certain human is asleep, then the human cannot laugh. Avicenna also explains more clearly than Aristotle what it means for something to be said essentially of a subject. After all, you can only tell so many jokes about Mullah Nasruddin.