It occurs to me that there are different kinds of composers. I just did a post on Steve Reich talking about his pieces that involve some sort of text or message ("Trains and Planes"). As a matter of fact, in each case, I think the position that he appears to take is a humanist one, that is, showing compassion for human suffering. For that reason, I would characterise him as a humanist. A lot of composers probably are humanists, though in the absence of any kind of indicative text, I'm not sure how we would know for sure. Some other "humanist" composers: Joseph Haydn, Mozart, J. S. Bach, Beethoven, Shostakovich, Messiaen--well, you could go on and on. I think that it would be very easy to find numerous examples for each of these composers showing a humanist orientation.
But what about those other categories? Who would be characterisable as an ideologue, for example? I would define "ideologue" as someone who is in the grip of an ideology. These are usually, it seems to me, totalitarian in nature. Examples would include fascism, Nazism, communism and so on. Human compassion comes a distant second to following the strict demands of the ideology. So who among composers might we put in this category? For artists, the category is much fuzzier than it would be in the political realm. A musical ideologue could be someone like Pierre Boulez who was utterly loyal to a kind of zeroing out ideology that declared all pre-serial music to be worthless--at least if it were composed now. For Boulez and his followers nothing could excuse the back-sliding tonal music of composers like Sibelius and Shostakovich. Other obviously ideological composers would include Cornelius Cardew, Fredric Rzewski and possibly someone like John Luther Adams, that is, if you consider environmentalism to be an ideology, which I do.
That leaves the category of careerism. I believe that composers of this ilk might not be really responding to an aesthetic vision, but rather reading the tea-leaves of the culture and coming up with something that follows some cultural trend. Someone once said that Stockhausen was always just five minutes ahead of what was fashionable--this is a critique of him as a careerist. Apart from him, who else might fit in this category? Bear in mind that there is a lot of guesswork involved, but someone who seems to respond all too readily to the needs of the cultural marketplace seems to fit. These are still serious artists, though, so the response might be indirect or delayed or even anticipatory as in the case of Stockhausen. I think that a likely example for this category would be Stravinsky, who always seemed to be catching the wave: exotic ballet, primitivism, neo-classicism and finally serialism. He also seems to prove that you can be both a careerist and a great composer.
This last point seems to show that these categories do not map directly onto aesthetic quality. Presumably you could be a first-rate humanist and a poor composer, just as you could be a careerist and yet a first-rate composer. I'm not so sure about ideologues; I suspect that the ideology pretty much stands in the way of the music, but I could be wrong. Would anyone like to venture some examples either way?
Let's have an envoi illustrating one of these categories. How about "Song for the British Working Class" by Cornelius Cardew: