Critique of second argument for the thesis

Critique of Premise 1
Some people might think that blind people can have ideas of colors, but supposed cases can be broken down into two categories, (a) those who are not totally blind from birth, and (b) those who are. The examples of (a) do not apply to the premise. They have had impressions. So Stevie Wonder is now blind, but was not born blind. He has an idea of red. Cases in category (b) are more troublesome because here Hume must say the individuals do not have any ideas of color. But of course such people use color words and can say that blood is red, grass is often green, and ripe lemons are yellow. [defense]

Critique of Premise 2
This premise is unobjectionable.

Critique of Premise 3
This premise is clearly true. This is just what it means to be cured of blindness or deafness--that the person can see or hear again, that is, the person has visual or auditory impressions.

Critique of Premise 4
This premise is even less objectionable than the previous two. When people can see, they have visual impressions. That is just what it means to have an impression.

Critique of Premise 5
Someone might object to this premise by saying that I could have an impression of the taste of kumquat without ever having tasted one because someone might describe the taste to me. This premise is shakier than premise 1. If I have a working tongue (and nose, perhaps) I know what tastes are. So this is not a case of being deprived of a sense. Can't one describe some tastes in terms of others? [defense]

Critique of Premise 6
This premise is perhaps the least plausible of all. It seems that a person who never felt cruelty could still know what cruelty is. [defense]

Critique of Inference
The argument here, although it is from a small set of examples, is convincing as far as it goes (if one grants the premises). But notice that this does not come anywhere close to establishing the thesis it is apparently intended to establish. All it establishes is that visual ideas are derived from visual impressions, and in general ideas of any inward or outward sense are derived from corresponding impressions.

But Hume's thesis is more radical than this. Hume has claimed [text] that all our ideas are derived from impressions. It is far from obvious that all our ideas are sensory ideas. Indeed, one might think that abstract ideas, such as justice, identity, difficulty, freedom, and plenty of others, are not dependent on the senses at all. This argument does nothing to show that they are.

Defense of the first argument against the critique
In regard to the critique of premise 1, it is the second category (b) of blind people which matters. Yes, these people who have been blind from birth do use color words. But Hume would contend (rightly, I think) that these people do not really have the ideas we do. They use the words, but they do not really know what real redness, greenness, and yellowness are. If such a person says "the color red is like the sound of a trumpet" she shows her ignorance. While this is nice poetry, colors are really not like sounds.

The critique of premise 5 suggests that one might be able to describe some tastes in terms of others. The same might apply to colors and sounds. The real problem here is the distinction between simple and complex ideas. To the extent that I come to have an idea of the taste of a kumquat by description, the idea seems to be complex and built out of other ideas (sweetness, for example) that I do have corresponding impressions of. [footnote 1]

In reply to the critique of premise 6 Hume might respond that the person who has never felt cruelty might know about cruel acts because the person will have seen them and indeed may have felt the brunt of them. But Hume might claim that the person will still be lacking some idea, namely that of how cruelty feels. Someone might claim that a ten year old can speak of feeling of (sexual) love, but does not "really" have an idea of what they are until she herself feels them a few years later.

Evaluation of first argument in light of critique
As I read it, by itself this argument fails miserably to establish Hume's thesis, although it does inductively support a weaker thesis, namely that all our sensory ideas are derived from sensory impressions.

1. This problem is addressed by Hume, albeit unsatisfactorily, in the "missing shade of blue" problem, discussed elsewhere.