Essay Question # 3
John Locke explains the distinction between primary and secondary qualities of
an object in Chapter 2: Book 8 of An Essay Concerning Human Understanding. The
distinction between primary and secondary qualities can be understood by distinguishing
“ideas or perceptions in our minds; and as they are modifications of matter in the bodies
that cause such perceptions in us” (Locke Ch.8, Sec. 7). The distinction between ideas
and modifications that cause such perceptions provide an important understanding that
continues to be explained through the delineation of the distinction between primary and
secondary qualities.
Primary qualities are “utterly inseparable from the body. . . the mind finds
inseparable from every particle of matter, though less than to make itself singly be
perceived by our senses” (Locke Ch8., Sec. 8). These primary qualities exist no matter
how large or small the object is, can never be taken away from the object, and can be
perceived regardless of the conditions that it is perceived in. These qualities can be
understood as qualities such as “solidity, extension, figure, or mobility” (Locke Ch8.,
Sec. 8). These primary qualities “produce simple ideas in us, viz. solidity, extension,
figure, motion or rest, and number” (Locke Ch. 8, Sec. 8). Primary qualities can be
understood as objective qualities inherent in the object with or without being experienced
or mentally grasped by a human being. For example,
Secondary qualities do not possess meaning on their own their own but instead
come to fruition as thoughts or sensations connoted by primary qualities. These
secondary qualities are produced in the mind when a primary quality is apprehended.
Secondary qualities include things such as colors, tastes, sound, etc. (Locke Ch.8., Sec.
10). While it may immediately seem as though these qualities are inherent to an object,
this is not necessarily so because secondary qualities are of a subjective nature. For
example, snow causes thoughts of white and coldness in us.
The notable distinction between the two kinds of qualities is understood with
relation to the fact that secondary qualities are subject to change and can be taken away,
whereas primary qualities persist within the object despite change in its composition. For
example, a grain of rice has the same solidity (primary quality) even when divided into
the most minute particle. This distinction is put forth in Chapter 8, Section 9 as Locke
explains that primary qualities retain their character and “all the forces can used upon it,
it constantly keeps; and such as sense constantly finds in every particle of matter which
has bulk enough to be perceived.”
Whereas secondary qualities can change or disappear given a particular force, for
example a rock with the color red in it could lose all appearance of color in a room with
no light (Locke Ch.8, Sec. 19). The distinction is crucial to the understanding of the two
types of qualities within external objects because it explains how from different
perspectives people might have differing experiences with the same stimulus. Locke
used the example of two bowls of water that are the same temperature, yet conger
different sensations in a person who places their hands in the bowls. The sense difference
comes from the fact that the person placed their hands in warm and cold water prior to
the bowls of the same temperature water, thus creating differing sensations in his hands.