Key Arguments

• Locke notes that a man 'may choose whether he will curiously survey' an object and 'with an intent application endeavour to observe accurately all that is visible in it,' indicating voluntary control over degree of attention and examination.
• Yet 'what he does see, he cannot see otherwise than he does'; he cannot will to 'see that black which appears yellow; nor to persuade himself that what actually scalds him, feels cold,' nor make 'the earth' appear 'painted with flowers' in winter, showing that our will cannot alter how clearly discovered objects appear to us.
• He generalizes: 'Just thus is it with our understanding: all that is voluntary in our knowledge is the employing or withholding any of our faculties from this or that sort of objects, and a more or less accurate survey of them,' clearly restricting voluntariness to selection and scrutiny, not judgment of truth.
• Once ideas are before the mind, 'our will hath no power to determine the knowledge of the mind one way or another; that is done only by the objects themselves, as far as they are clearly discovered,' so perception of agreement or disagreement follows necessarily from clear apprehension.
• Accordingly, 'as far as men’s senses are conversant about external objects, the mind cannot but receive those ideas which are presented by them, and be informed of the existence of things without,' and similarly, when thoughts 'converse with their own determined ideas, they cannot but in some measure observe the agreement or disagreement that is to be found amongst some of them,' which constitutes knowledge.
• If we also 'have names for those ideas which they have thus considered,' we 'must needs be assured of the truth of those propositions which express that agreement or disagreement they perceive in them, and be undoubtedly convinced of those truths,' because perception of agreement makes assent unavoidable.

Source Quotes

The application of our faculties voluntary; but, they being employed, we know as things are, not as we please. There is also another thing in a man’s power, and that is, though he turns his eyes sometimes towards an object, yet he may choose whether he will curiously survey it, and with an intent application endeavour to observe accurately all that is visible in it. But yet, what he does see, he cannot see otherwise than he does.

There is also another thing in a man’s power, and that is, though he turns his eyes sometimes towards an object, yet he may choose whether he will curiously survey it, and with an intent application endeavour to observe accurately all that is visible in it. But yet, what he does see, he cannot see otherwise than he does. It depends not on his will to see that black which appears yellow; nor to persuade himself that what actually scalds him, feels cold.

But yet, what he does see, he cannot see otherwise than he does. It depends not on his will to see that black which appears yellow; nor to persuade himself that what actually scalds him, feels cold. The earth will not appear painted with flowers, nor the fields covered with verdure, whenever he has a mind to it: in the cold winter, he cannot help seeing it white and hoary, if he will look abroad.

The earth will not appear painted with flowers, nor the fields covered with verdure, whenever he has a mind to it: in the cold winter, he cannot help seeing it white and hoary, if he will look abroad. Just thus is it with our understanding: all that is voluntary in our knowledge is the employing or withholding any of our faculties from this or that sort of objects, and a more or less accurate survey of them: but, they being employed, our will hath no power to determine the knowledge of the mind one way or another; that is done only by the objects themselves, as far as they are clearly discovered. And therefore, as far as men’s senses are conversant about external objects, the mind cannot but receive those ideas which are presented by them, and be informed of the existence of things without: and so far as men’s thoughts converse with their own determined ideas, they cannot but in some measure observe the agreement or disagreement that is to be found amongst some of them, which is so far knowledge: and if they have names for those ideas which they have thus considered, they must needs be assured of the truth of those propositions which express that agreement or disagreement they perceive in them, and be undoubtedly convinced of those truths.

And therefore, as far as men’s senses are conversant about external objects, the mind cannot but receive those ideas which are presented by them, and be informed of the existence of things without: and so far as men’s thoughts converse with their own determined ideas, they cannot but in some measure observe the agreement or disagreement that is to be found amongst some of them, which is so far knowledge: and if they have names for those ideas which they have thus considered, they must needs be assured of the truth of those propositions which express that agreement or disagreement they perceive in them, and be undoubtedly convinced of those truths. For what a man sees, he cannot but see; and what he perceives, he cannot but know that he perceives. 3.

Key Concepts

• There is also another thing in a man’s power, and that is, though he turns his eyes sometimes towards an object, yet he may choose whether he will curiously survey it, and with an intent application endeavour to observe accurately all that is visible in it.
• But yet, what he does see, he cannot see otherwise than he does.
• It depends not on his will to see that black which appears yellow; nor to persuade himself that what actually scalds him, feels cold.
• Just thus is it with our understanding: all that is voluntary in our knowledge is the employing or withholding any of our faculties from this or that sort of objects, and a more or less accurate survey of them:
• but, they being employed, our will hath no power to determine the knowledge of the mind one way or another; that is done only by the objects themselves, as far as they are clearly discovered.
• For what a man sees, he cannot but see; and what he perceives, he cannot but know that he perceives.

Context

Book IV, Chapter XIII, §2 (mainly), where Locke extends the vision analogy to specify the exact sense in which knowledge is voluntary and insists that truth is determined by clearly perceived objects and ideas, not by will.