It is extremely common to hear people talk about “high art”, in the context of “literature”, to distinguish it from, say, “popular fiction”, and so on.
What justifies the idea that there is something “high” about some kinds of writing? What are the characteristics? Why does the concept exist? How can you know if something is “high art” or not?
Yes, it is extremely common to hear people talk about "high" art.
Imo, the justifications for it are implicit in culture(s), perhaps all cultures, since the notions of social hierarchies are virtually universal in the form of class structures, the existence of aristocracy, nobility, rank, and so on.
Given that, any extension of such hierarchies to art and literature is inevitable, if not natural and organic.
Knowing or identifying something as high art is not so inevitable as the ground truths for such constructs are not constants in the sense of the physical constants of astronomy and physics. In other words, aesthetics is a soft science where ground truths change from culture to culture, regimes of belief and time.
This reality hasn't stopped people from trying to define the boundaries of high art. Among the notable literary statements of this is Matthew Arnold's mid-19th c essay Culture and Anarchy. Arnold's definition boils down to "the best that has been thought and said" by great men in great cultures in the pursuit of perfection.
Perhaps one of the best recent statements about this is George Steiner's In Bluebeard's Castle, a book which critiques Arnoldian views of elite or high culture as having been erased by Holocaust Nazis reading poetry and performing Mozart cheek-by-jowl with camp ovens. In other words, the humanities fail to humanize and elite cultures are guilty of the worst atrocities capable of commission by humans.
Literature is not exempt from this indictment.
Nevertheless, the parameters of high vs low include an entities' novel or rare features, its popularity, its price, critical opinions, just for starters.
“High art” is a phrase that has accrued various cultural associations and implications, wherever it came from. One methodological issue with critiquing or disputing it is that words arise organically through human use, so it is hard to definitely assert what something means, because the use can change based on any changes in intuition or desire by people who use it. In fact, I think it might be more common for words to change meaning regularly rather than stay fixed, but that is a question worthy of more exploration.
The empirical view on the question would simply try to observe how people have been using the term and what seems to be implied in it, without a) claiming it is a “real” thing, as opposed to just, a concept some people have used, or, b) claiming it is not a “real” thing, again, merely as opposed to a concept that exists insofar as people mean something (apparently) when they say it - even if it implies beliefs they hold you don’t agree with or find false. In that case, it would be better to say it is a concept which carries assumptions that you find false, in my opinion, than to say it is or is not a “real thing”.
I do not find the concept useful or of benefit, in my life, right now, and that could change. Social phenomena are very diverse. Cultural contexts can vary widely, and human desires and whims and motivations and drives can surprise us, where they can go, based on myriad factors in a cultural or historical context - some overt and known, some hidden and latent.
To me, the concept of “high art” as I have at least encountered it, to give only one prototypical example, in some of the attitudes implied by a literary critic such as Harold Bloom, but there are myriad others, essentially rests on a pretty strong philosophical, epistemological belief or thesis that there is an inherent quality to “a work of literature”, and, furthermore, it has some kind of inherent capability for valuation. In other words, such a perspective might claim that there is some inherent property called “aesthetic profundity” or aesthetic value - they might (at least the attitudes that I have encountered) say a piece of music by Bach is somehow more worthy of cultural attention and import than say, the writing on a candy bar wrapper.
I don’t think philosophical questions about “what makes an artwork valuable” are that complicated (but maybe I haven’t thought about it enough), but is heavily bound up in prescriptive aspects of human thought - in that regard, perhaps aesthetic theory can learn the most from moral philosophy, since it may be a field of thought that has to embrace making “should” statements if it is to exist at all. The purely descriptive view can say nothing much about what anyone should read or care about or do, what books should be taught in schools, etc.
I guess my views on morality and various cognitive-sensory experiences (included but not at all bounded by a concept “art” or “artwork”) fulfilling in their own way, are sort of “pragmatist”: there is no inherent moral requirement beneath it all, but we might find situationally that as humans, short of being genuine nihilists (which very few people truly are, it seems - anyone who cares for anything, their life or the life of another of their aims or what have you), we all find it worth our time to engage in and formulate some kind of “should”-type beliefs, but to me, they are local and relative to a given situation, and never fixed forever, absolute or born by pure inherent necessity or mandatory principle alone.
There may well be some aspect of things like Walt Whitman or Shakespeare that does qualify them in a certain group compared to some electronic music your brother made, but the moralizing side, I think, one is to be very wary of: trust in your instincts: don’t let anyone tell you what is good or bad: find out for yourself: question and critique those powerful voices who want to tell you otherwise, to like other than what you like, or think other than what you think. I have found it liberating to reject the idea that “high art” exists, is important, or is something worthy of devoting a lot of time and energy to. This has allowed me to have a way more authentic relationship to the world of creativity, creative thinking, and new types of experiences.