if i were to define knowledge, i would certainly include aesthetics as knowledge - art, or music, or alternatively a creative jump or intuition, are a way of knowing. people can know things are good, or beautiful, even if there is not some hard fact which makes it so. there is no objective measure that demonstrates that charity is good, or that mozart is beautiful - nevertheless it is known. and to break these things down into some constituent and mechanical explanation ("charity can materially improve the life of someone who is impoverished," "scientists can measure the parts of the brain activated by music") is to strip down the human experience to its materialist components - which is an impoverished worldview.
as for you're comments, yellowjacket, if you read what i have said here, in my very first comment i describe a universal moral position as one that is empty - we cannot flesh it out, so much as strive toward it. thus, you cannot name the a particular moral law, for example, because it will always be a social or a linguistic or a politically motivated construction, or something along those lines. and so, purging immoral behavior does not factor into my position.
indeed, dissenting opinion is essential, as people will always be striving to articulate a universal statement. while they will fail, they will formulate their perspectives in relation to one another, sometimes building on what others done and sometimes actively arguing against it.
as an example cited in this discussion, there is the moral equality of all people. in practice this is hotly contested with many different formulations of what that means, many of those formulations mutually exclusive, yet all responsive to one another and part of the same continuous human discourse on this topic. and, indeed, there is no proof or evidence that it is true. but providing evidence that it is true, is of course, beside the point.