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The primary/secondary quality distinction is a conceptual distinction in epistemology and metaphysics, concerning the nature of reality. It is most explicitly articulated by John Locke in his ''Essay concerning Human Understanding'', but earlier thinkers such as Galileo and Descartes made similar distinctions. Primary qualities are thought to be properties of objects that are independent of any observer, such as solidity, extension, motion, number and figure. These characteristics convey facts. They exist in the thing itself, can be determined with certainty, and do not rely on subjective judgments. For example, if a ball is spherical, no one can reasonably argue that it is triangular. Secondary qualities are thought to be properties that produce sensations in observers, such as color, taste, smell, and sound. They can be described as the effect things have on certain people. Knowledge that comes from secondary qualities does not provide objective facts about things. Primary qualities are measurable aspects of physical reality. Secondary qualities are subjective. ==History== * "By convention there are sweet and bitter, hot and cold, by convention there is color; but in truth there are atoms and the void" :—Democritus, Fragment 9.〔Quoted by Sextus Empiricus, ''Adversus Mathematicos'' vii 135〕 * "I think that tastes, odors, colors, and so on are no more than mere names so far as the object in which we locate them are concerned, and that they reside in consciousness. Hence if the living creature were removed, all these qualities would be wiped away and annihilated" :—Galileo Galilei, ''The Assayer'' (published 1623).〔As reprinted in (Drake, 1957, p. 274)〕 * "()t must certainly be concluded regarding those things which, in external objects, we call by the names of light, color, odor, taste, sound, heat, cold, and of other tactile qualities, (); that we are not aware of their being anything other than various arrangements of the size, figure, and motions of the parts of these objects which make it possible for our nerves to move in various ways, and to excite in our soul all the various feelings which they produce there." :—René Descartes, ''Principles of Philosophy'' (published 1644/1647).〔Descartes, René. ''Principles of Philosophy''. 1644/1647. Trans. Valentine Rodger Miller and Reese P. Miller. D. Reidel Publishing Company, 1984. Page 282.〕 * "For the rays, to speak properly, are not coloured. In them there is nothing else than a certain power and disposition to stir up a sensation of this or that colour." :—Isaac Newton, ''Optics'' (3rd ed. 1721, original in 1704).〔Reprinted in (Newton, 1953, ed. Chris Jamieson, p. 100)〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Primary/secondary quality distinction」の詳細全文を読む スポンサード リンク
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