Why did not Locke write 'Qualities', when he meant Qualities by '‘ideas’ as in the things themselves'?

Question

_{Source: p 208, Introducing Philosophy for Canadians: A Text with Integrated Readings (2011 1 ed).
Primary Source: Book 2, Chapter 8, ¶ 8, An Essay Concerning Human Understanding (1689) by John Locke.}

8. Our ideas and the qualities of bodies. Whatsoever the mind perceives in itself, or is the immediate object of perception, thought, or understanding, that I call idea; and the power to produce any idea in our mind, I call quality of the subject wherein that power is. Thus a snowball having the power to produce in us the ideas of white, cold, and round,- the power to produce those ideas in us, as they are in the snowball, I call qualities; and as they are sensations or perceptions in our understandings, I call them ideas; which ideas, if I speak of sometimes as in the things themselves, I would be understood to mean those qualities in the objects which produce them in us.

_{[ 2007 Paraphrase by Jonathan Bennett :]} 8. Whatever the mind perceives in itself—whatever is the immediate object of perception, thought, or understanding—I call an idea; and the power to produce an idea in our mind I call a quality of the thing that has that power. Thus a snow-ball having the power to produce in us the ideas of white, cold, and round, the powers to produce those ideas in us, as they are in the snow-ball, I call qualities; and as they are sensations or perceptions in our understandings, I call them ideas. If I sometimes speak of ‘ideas’ as in the things themselves, please understand me to mean to be talking about the qualities in the objects that produce them in us.

I do not comprehend the reason behind the last sentence above (that I coloured in grey). If Locke meant Qualities, then why did he still write 'ideas' instead of simply writing 'Qualities'?

Answer 1

He is speaking of ideas in two different senses. You can think of them as causes and effects:

1. Causes: The qualities which objects have ("as in the things themselves") that give them the capacity to bring about effects within us.

2. Effect: The phenomenal qualities that we perceive as a result of objects affecting us.

Answer 2

Ideas are in the mind, qualities are in objects

Briefly, for Locke qualities and ideas are different. Qualities are in objects; ideas are in the mind. But Locke's language in the Essay does not always respect this distinction.

Consider this extract from the Essay concerning Human Understanding :

Whatsoever the mind perceives in itself. . .that I call idea; and the power to produce any idea in our mind I call quality of the subject wherein that power is. Thus a snowball having the power to produce in us the ideas of white, cold and round, the powers to produce those ideas in us, as they are in the snowball, I call qualities; and as they are sensations or perceptions in our understandings I call them ideas; which ideas if I speak of sometimes as in the things themselves, I would be understood to mean those qualities in the objects which produce them in us. (II.viii.8.)

The final line is an admission that Locke sometimes refers to 'ideas' when he intends 'qualities'. However, despite this looseness of language Locke does regard qualities and ideas as distinct entities. They are totally separate concepts. Qualities and ideas are never identical.

The ambiguity of 'appearances'

Not only does this particular looseness of language occur but Locke adds to the reader's problems in his use of the term, 'appearances'. This can sometimes refer to ideas and sometimes to qualities. Jonathan Bennett brings out the point well :

According to Locke, the mental content (the "idea") that someone associates with a classificatory word determines what he means by it: my idea of squareness delimits what I mean by "square." One can also plausibly suppose that the meaning of any such word is determined solely by the qualities a thing must have for that word to be applicable to it: the property of squareness delimits what I mean by "square." Consider this passage, for example:

Such. . .appearances in the mind...the understanding lays up (with names commonly annexed to them) as the standards to rank real existences into sorts, as they agree with these patterns, and to denominate them accordingly. Thus the same colour being observed today in chalk or snow which the mind yesterday received from milk, it considers that appearance alone, makes it a representative of all of that kind; and having given it the name whiteness, it by that sound signifies the same quality wheresoever to be imagined or met with. (II.xi.9.)

In that passage, the first "appearances" are what "ideas" are officially supposed to be, namely something "in the mind;" but further down, the phrase "that appearance alone" refers to a quality, a color observed in milk yesterday and snow today. (Jonathan Bennett, 'Ideas and Qualities in Locke's "Essay"', History of Philosophy Quarterly, Vol. 13, No. 1 (Jan., 1996), pp. 73-88: 82.)

Bennett's point is well taken but it only shows a further instance of Locke's looseness of language. Locke may use 'appearances' carelessly but the concept of a quality and the concept of an idea remain totally distinct.