While Victorian fiction ushered in the focus on realism that continues in much of modern fiction, many readers prefer less realistic works, choosing fantasy tales and other forms of escapist literature.
For me, fiction is mostly a diversion from the real world. Good fiction will encompass all of the ideas you mentioned; if it isn't thought provoking, it's probably not of a very high caliber. But entertainment should certainly be the foremost emotion received when reading fiction.
I certainly agree that it is a combination of everything because what really comes into play is the connection that the reader makes to the text. What one reader feels about a work if fiction is different from what another reader feels.
For example, while a puritan and over-virtuous and hypocritical "select" in Victorian England felt insulted and shocked by the publication of The Picture of Dorian Gray (pardon my constant mention to Oscar Wilde), a smaller section of society felt impressed by Wilde's gall in exposing the reality of the so-called London gentlemen who actually paid for services of low rate men escorts while leading a prudish life at home with their wives and children. Others felt inspired to continue to "open the can" and investigate these practices, as a result of that publications. Others, as it was exposed during Wilde's trial, dedicated themselves to observe the Criminal Amendment act of 1885 and fight against it.
Therefore, one simple work can inspire a series of emotions that, ultimately ,lead to some form of action. Fiction is what the reader wants it to be. Like I tell my students: Fiction finds you!
A lot of great fiction does all of the above. I admire some fiction purely for the technical skill of the author. James Joyce might fall into that category in the past, and Jonathan Franzen is that way for me today. Two very different writers, but I appreciate them primarily as writers.
Other important works of fiction have far transcended art, and moved into the realm of activism. Uncle Tom's Cabin is a wonderful example of this. The Jungle is another. Not as well-executed as many others, but important beyond their literary merits.
Good literature can be written with a number of purposes in mind, and can affect readers in different ways.
A combination. In his Preface to The Great Gatsby, Michael J. Bruccoli writes,
Literature has staying power, but it is subject to metamorphosis. Every reader's response to a work of fiction is determined by his or her presuppositional biases, beliefs, experience and knowledge.
Fiction can provide much more to the cultivated reader although it can provide entertainment, escape, and insight to even the rudimentary.
"Should the main purpose of fiction be to entertain, to educate, to provoke thought, or a combination of these?" is a question whose answer defines the meaning of "a classic." Classic literature provides all levels and thus is timeless as it can appeal to the child, the ingenuous, the sophisticated, the jaded, the experienced, the poorly educated, the erudite.
I don't think there is one finite answer and actually think you could argue that reading fiction can be a multifaceted and interdependent process. Some literature is entertaining because it is thought provoking. Some literature is thought provoking because it educates us about some aspect of life. For example, satire is highly entertaining (uses humor) for the purpose of educating (pointing out a flaw in human nature). For this reason, in addition to the points made above, I don't think there is one neat and tidy answer.
The main purpose of fiction should be to do whatever the author wants it to do. If the author wants the fiction to try to teach us lessons about the human condition, fine. But if the author simply wants to be entertaining so as to sell more books and make more money, that's fine too. There is and should be a difference between high culture and mass culture in fiction as in many other genres.
The main purpose of fiction is to entertain, but it achieves its other purposes by entertaining. Sometimes fiction informs us more because we are in the process of being entertained, and so we actually learn more or are persuaded more.
I definitely believe its a combination of these. All these emotions are happening when reading or writing fiction
This is too large of a question to answer definitively; it is the type of question that is the basis for a doctoral thesis or an entire book on literary theory in order to give a definitive answer. But, then that definitive theory would be only one person's understating of what fiction is.
There are several different accepted working definitions that we can extract a purpose from. Jim Meyer contends that literature is:
careful use of language, being written in a literary genre (poetry, prose fiction, or drama), being read aesthetically, and containing many weak implicatures.
From this we can extrapolate that the purpose of fiction is to be an example of great writing that about events that did not actually happen. While this definition of literature is very neat and concise, it seems to not truly capture what the essence of fiction really is.
Therefore, an alternative understanding of how to define the purpose of literature can be found in linguistic theory. Linguistic relativity, also known as the Sapir–Whorf hypothesis, is the idea that language itself influence show we conceptualize our world. This can be demonstrated in the ways that the same events, the same ideas and objects, the same collective reality, does not translate perfectly from language to language.
All of this leads us to conclude that the main purpose of literature, the main purpose of fiction, or any other type of writing, should be dictated by the needs and desires of those involved, the desired outcomes, and the current situation the choice exists within.
I know this is not a nice, neat and concise answer. If you were to ask my personal opinion I would say that the purpose of fiction should be to explore the human condition. But, that is only my opinion. There are theorists and novelists, college professors and doctoral candidates who would say something completely different. As you said, the Victorian era ushered in a renewed commitment to realism because that's what writers needed at the time and that's what readers wanted just as a post-modernism has produced hyper-realism and the depression era needed escapism.
Fiction is made up so it won't be to educate... I think it's to entertain becuase Non-Fiction does educate us.
On the other hand, someone else can argue the opposite so I'm not quite sure.