Thus, Locke devoted careful attention to our use of the...

Thus, Locke devoted careful attention to our use of the faculty of sensory perception, the passive ability to receive ideas from the external world by means of our sensory organs. The simple ideas acquired by attending to these mechanical operations are the first components of all human thought.

[Essay II ix 1-6] Although sensitive knowledge is strictly limited in its scope and reliability, Locke held that the testimony of sensory experience, lying as it does entirely outside our voluntary control, provides all the evidence we can have-and all the evidence we need-of the existence, nature, and operation of physical objects. [Essay IV xi 2-6] Space and…