Theory of Knowledge


Additional Information


  Primary and Secondary Qualities


If we reject, as the Empiricists do, the idea that all our knowledge comes from rational principles, we are left with a major question: How can we tell which of our perceptions are real or true? Locke's answer is to suggest the existence of what he calls primary and secondary qualities.

First of all, let us consider an object - a table, for example. Now, Locke's view is that certain qualities of the table are primary qualities of the object (such as the table's shape and size), but others are produced by powers in the object itself, which act on our senses to produce sensations and impressions. Such things as colour, taste and temperature are therefore secondary whilst other primary qualities include number (how many objects there are) and motion (an object's speed or movement).



The main thing Locke was trying to do is to limit knowledge to the things that could be said to be primary qualities. So, as far as the table is concerned, such things as its size, shape and weight are fixed and measurable. Its colour, on the other hand, is a matter of subjective opinion.


Of the simple and complex ideas you listed in the previous example, which are primary and which are secondary? Go through your lists and mark P or S next to each one.

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