On run-on sentences, Wikipedia says:
This is generally considered a stylistic error, though it is occasionally used in literature and may be used as a rhetorical device.
At the end of the article it describes how run-on sentences are used in literature. For example, some authors use them to depict stream of consciousness. Is that a rhetorical device or just an example of it used in literature? What valid uses are there for run-on sentences?
This is opinion based and maybe better asked at a writer's site.
James Joyce used run-on sentences to great effect in Ulysses, which, if I recall correctly, has the longest sentence in English Literature. Does the style need a raison d'etre other than that the author uses it skillfully?
If one is trying to recreate human thought processes (or conversation, for that matter), run-on sentences and sentence fragments are much more representative of thought/speech than 'proper' writing. Also, if one is trying to accurately portray speech patterns in certain types of mental illness, it would be far better to use run on sentences. We rarely think in well-developed sentences, although it is the better way to communicate our thoughts.
An encouraged use for run-on sentences is in certain types of journaling, in which one writes whatever comes to mind whenever, to uncover thoughts which might be otherwise be kept hidden.
It is not commonly encouraged in writing classes because it is often just laziness. When used purposefully, it is difficult to carry off well. Also, bad run-on sentences make reading hard work, whether one believes in an interactive or modular approach to reading.
The question, I believe, is one that matters more on what you consider a "run-on sentence" rather than any hard and fast rule such as "don't use run-on sentences"; so long as the grammar is correct and you cannot without losing meaning or cadence split a sentence, it is valid no matter how long it may be.
Is a "run-on" sentence one that could be split in two? Or is it one that grammatically SHOULD be split in two? Or three? Because when you ilk into wordy description, you wind up with what can be absurdly long sentences which could not be split without significant revision, and are nevertheless valid.
Victoria may be right about grammar but as a great author once said: Screw grammar, make it entertaining. (btw that was Stephen King) If a sentence works best as a run on and not two separate sentences then keep it.
A good rule of thumb is the thought rule. If a sentence is one thought, the next sentence should be a following thought. If a sentence cannot be broken into two thoughts; it's valid. I would consider maybe separating an independent clause within the run on however with a semicolon (but don't overuse this) as it offers a more complete stop then a comma but still continues the singular thought better than a full stop.
A run-on sentence is, by definition, grammatically incorrect. Whether something is a run-on sentence is not a matter of opinion. A sentence may include many clauses and go on for a paragraph or page or more and not be a run-on because it cannot be divided into separate complete sentences. A run-on is two or more distinct sentences (complete thoughts with a subject and verb) in which commas are used where periods or semi-colons should be. I agree this is a valid literary device when used in stream-of-consciousness or in dialogue, though it's a little harder to justify in dialogue. It's true that people don't generally speak in complete sentences, but fragments or stringy sentences (a long string of phrases and clauses) more accurately represent casual speech. If a character has used two complete sentences, why write them as one? The only justification I can think of for this is if the author is trying to show that the character is speaking very fast and doesn't stop for breath between thoughts. In some popular novels I've read recently, the authors use run-on sentences that aren't in dialogue or stream of consciousness and seem to serve no purpose. This suggests a lack of command of the language that, in my opinion, undermines their authority as writers, even if it doesn't necessarily make the text difficult to read. Knowing that these books have been published by major publishing houses and gone through editors has made me wonder if this is becoming trendy. I am all for playing with language and experimenting if it works, but I feel you need to know the rules and have a good reason for breaking them before you can justify doing so.
