De Anima

This is my understanding of some of the pages of Aristotle's De Anima.

Aristotle makes a distinction between three different things: something that is potentially existent, its actuality and its full actuality. In the text we can see three examples of this: the axe, the eye and the soul. In the example of the axe, the thing that is potentially existent is the axe its actuality is the capacity of the axe and its full actuality is an axe cutting. In the example of the eye we have as potentially existent the pupil, the actuality is the eyesight and its full actuality is the seeing of the eye. In the case of the soul, we have as potentially existent the body, as its actuality the soul and as its full actuality the waking state.

When we talk about the soul and the body, we must always keep in mind that the soul and body together is an animal. But if we apply the phrase “By that which has in it the capacity of life is meant not to the body which has lost its soul, but that which possesses it”, meaning that only a body with a soul can have the capacity of life, then if an animal is constituted by body and soul together, an animal is meant to have the capacity of life. Another thing to keep in mind while talking about the soul is that the soul cannot be separated from the body. Meaning that the soul cannot exist without a body.

“Life is that which distinguishes the animate from the inanimate.” From here we can assume that the animal with the capacity of life is animate. Aristotle also says that “If life is present but in a single one of these senses, we speak of a thing as living”. Then if an animal that has a capacity of life, has life it will either have it as intellect, sensation, motion from place to place and rest, the motion concerned with nutrition or decay and growth.

From this Aristotle gives an example of how plants can only life with growth, decay and the motion concerned with nutrition; and then compares these senses in plants to those in mortal creatures, saying that in a mortal creature, all of the rest of the senses cannot be separated from these three forms of life. So assuming that the animal, which is meant to have the capacity of life, is a mortal creature, then animals need to have growth, decay and the motion concerned with nutrition.

But the sense that really differentiates the animal from any other living thing is that the animals are primarily constituted by sensation. So, as long as a living thing has sensation, growth, decay and nutrition, it is said to be an animal. And by primary sense, we mean touch. And “Animals are found universally to have the sense of touch”, so all animals have touch.