The rise of modern philosophy a new history of western philosophy volume 3 (new history of western philosophy) ( PDFDrive ) (1) 151

KNOWLEDGE them or no.’ Light, heat, whiteness, and coldness, on the other hand, are no more really in bodies than sickness or pain is in food which may give us a stomach ache ‘Take away the sensation of them; let not the Eyes see light, or Colours, nor the Ears hear Sounds; let the Palate not Taste, nor the Nose Smell, and all Colours, Tastes, Odors and Sounds, as they are such particular ideas, vanish and cease’ (E, 138) This argument is inconsistent with what Locke has just said, namely, that secondary qualities are powers in objects to cause sensations in us These powers, to be sure, are only exercised in the presence of a sensing organ; but powers continue to exist even when not being exercised (Most of us have the power to recite ‘Three Blind Mice’, but rarely exercise it.) Locke claims that what produces in us the ideas of secondary qualities is nothing but the primary qualities of the object having the power The sensation of heat, for instance, is caused by the corpuscles of some other body causing an increase or diminution of the motion of the minute parts of our bodies But even if this were a true account of how a sensation of heat is caused, why conclude that the sensation itself is nothing but ‘a sort and degree of motion in the minute particles of our nerves’? The only ground for this conclusion seems to be the archaic principle that like causes like But to take an example of Locke’s own, a substance can cause illness without itself being ill Locke denies that whiteness and coldness are really in objects, because he says there is no likeness between the ideas in our minds and the qualities in the bodies This statement trades on the ambiguity we noted at the outset in the notion of an idea If an idea of blueness is a case of the action of perceiving blueness, then there is no more reason to expect the idea to resemble the colour than there is to expect playing a violin to resemble a violin If, on the other hand, the idea of blueness is what is perceived, then when I see a delphinium the idea is not an image of blueness, but blueness itself Locke can deny this only by assuming what he is setting out to prove Locke’s Wnal argument is an analogy between perception and feeling: He that will consider, that the same Fire, that at one distance produces in us the Sensation of Warmth, does at a nearer approach, produce in us the far diVerent Sensation of Pain, ought to bethink himself, what Reason he has to say, that his Idea of Warmth, which was produced in him by the Fire, is actually in the Fire; and his Idea of Pain, which the same Fire produced in him the same way, is not in the Fire (E, 137) 136