Immateriality of the Soul - Hume
Book 1, Part 4, Section 5
Of the Immateriality of the Soul
"As every idea is derived from a precedent impression, had we any idea of the substance of our minds, we must also have an impression of it."
impressions represent substances by resembling the substance
the mind is not a substance (according to Cartesians)
so, we cannot have an impression of the mind itself
if we cannot have an impression of the mind, then how do we get an idea of the mind?
Concerning the Cartesian definition of substance as that which can exist by itself
everything fits this definition
Principle 1: "Whatever is clearly conceived may exist, and whatever is clearly conceived after any manner may exist after the same manner."
Principle 2: "Everything which is different is distinguishable, and everything which is distinguishable is separable by the imagination."
Perceptions are different from themselves and everything else
Perceptions are distinct and separable
Perceptions can be considered separately
Perceptions can exist separately
Therefore, according to the Cartesian definition of substance, perceptions are substances
On substance
"We have no perfect idea of anything but of a perception."
"A substance is entirely different from a perception."
"We have, therefore, no idea of a substance."
On inhesion
"Inhesion in something is supposed to be requisite to support the existence of our perceptions."
"Nothing appears requisite to support the existence of a perception."
"We have, therefore, no idea of inhesion."
Thought and extension are incompatible and cannot incorporate in the same subject
Maxim: "An object may exist and yet be nowhere."
when its parts are situated so they have no figure or quantity
"nor the whole with respect to other bodies"
from our perspective, we cannot form any notion of its contiguity or distance
true of perceptions and objects other than those of sight and touch
they are incompatible with space
Hume, David. Treatise of Human Nature
