Final answer:
Aristotle defines the soul as the life principle that imparts the ability to act, distinguishing between vegetative, animal, and human souls with respective abilities for growth, perception, and rational thought. Contrasting Plato, Aristotle's functional conception based on the activities of living organisms doesn't regard the soul as an inseparable immortal substance.
Step-by-step explanation:
Aristotle defines the soul as the principle of life that imbues matter with the ability to act and is unique to all living things, distinguishing between vegetative, animal, and rational (human) souls. Unlike Plato, who deemed the soul to be an immortal and eternal substance separate from the body, Aristotle posited a functional view of the soul, elucidating the soul's role based on its operations and manifestations within living entities. Plants possess a vegetative soul, responsible for growth and nutrient exchange. Animals have this vegetative aspect plus the capacity for perception and voluntary movement, dubbed the animal soul. Furthermore, humans are endowed with these capabilities coupled with the rational soul, which grants the power of intellect and reasoned thought. Aristotle's perspective also stirs a discourse about the ensoulment and the misunderstanding propagated by Alexander of Aphrodisias, asserting a 40-day post-conception arrival of the soul, against Aristotle's likely belief in immediate ensoulment at fertilization as concluded by scholars such as Bos (2012).