Animal Intelligence and Vis Aestimativa in Avicenna and Thomas Aquinas
Avicenna and Thomas Aquinas understand animal intelligence in reference to the activity of vis aestimativa, through which they explain animal behaviour as being consequent to an apprehensive appraisal of its environment. This apraisal must be distinguished from the representative knowledge of the phantasma, because it is not of per se sensed qualities, but per accidens, that Avicenna calls intentiones. Explaining animal behaviour from the vis aestimativa allows to understand it without attributing it to intelligence, which has been classically considered to be exclusive of rational beings’ conceptual knowledge of reality.