Hume held that all experience and under his empiricism all ideas and meaningful thoughts were reducible to impressions. Thus, for Hume an 'idea' is merely a faint impression. But why should ideas and thought be put into the terms of impressions? Are not sensed ideas just as simple and ontologically important as impressions?
For example, let us say we have the experience of a 'man'. Hume would hold what we truly had the experience of was the skin, the eyes, the hair, which each in turn were experiences of certain colors, certain smells, etc. What we experienced wasn't 'really' a man at all but merely a certain set of distinct impressions. Hume's attitude can thus be shown to be of the opinion that the set should be understood in terms of that which comprises the set. But what is to say that the impressions which composite such a set are anymore simple than the idea 'man' which is the essence that categorizes the set? There is nothing intrinsically in the experience of a basic thing such as 'red' that makes it more simple than the experience of 'James the man' as a whole. Indeed, we only know the ontological difference between the two upon reflection, so there seems little reason to believe one should have ontological precedence over the over. In any case, such a claim requires support that Hume doesn't seem to provide.
Furthermore, if we were to reduce the set to that which comprises it it seems that there is a hole left for Hume to explain. For that there is a set to begin with requires explanation. That there is one out of many, both qualitatively and numerically, is the very thing attempting to be explained by the study itself, and in reducing the set to its supposed 'parts' there seems to not be answered the question that was most relevant to the pursuit.
Are these criticisms correct, and if so, did Hume ever anticipate them? Have his defenders ever given response to them?