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In Cartesianism: The way of ideas and the self
…Galileo’s distinction between real, or primary, properties of material bodies—such as size, shape, position, and motion or rest—which were thought to exist in bodies themselves, and sensible, or secondary, properties—such as colours, tactile feelings, sounds, odours, and tastes—which were thought to exist only in the mind. As Descartes assumes in…
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In John Locke: Primary and secondary qualities
In the course of his account, Locke raises a host of related issues, many of which have since been the source of much debate. One of them is his illuminating distinction between the “primary” and “secondary” qualities of physical objects. Primary…
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$optical illusion: refraction of light$
In epistemology: Epistemology and modern science
Whereas primary qualities—such as figure, quantity, and motion—are genuine properties of things and are knowable by mathematics, secondary qualities—such as colour, odour, taste, and sound—exist only in human consciousness and are not part of the objects to which they are normally
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In Western philosophy: Philosophy of nature
…resultant important distinction between “primary” and “secondary” qualities. The former qualities—including shape, extension, and specific gravity—were considered to be part of nature and therefore real. The latter—such as colour, odour, taste, and relative position—were taken to be simply the effect of the motions of physical bodies on perceiving minds…
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In Western philosophy: Reason in Locke and Berkeley
…the important distinction between “primary qualities” (such as solidity, figure, extension, motion, and rest), which are real properties of physical objects, and “secondary qualities” (such as colour, taste, and smell), which are merely the effects of such real properties on the mind.
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