What Is a Comma Splice? Joining Two Sentences With Too Little

A comma splice joins two independent clauses, meaning two groups of words each containing a subject and a verb and each capable of standing alone, using only a comma. The standard objection is that a comma is not strong enough to carry that join, and that a reader encountering one expects the sentence to continue rather than to restart. The conventional remedies are straightforward: separate the clauses with a full stop, join them with a semicolon, add a coordinating conjunction after the comma, or subordinate one clause to the other so that it is no longer independent. Which remedy is right depends on the relationship between the two statements, since a full stop separates them, a semicolon links them as equals, a conjunction states the relationship and subordination makes one serve the other, and choosing correctly is a matter of meaning rather than of avoiding an error.

The error has identifiable causes and recognising them helps:

• •Speech rhythm, since the two clauses are spoken in one breath and the writer punctuates by ear
• •Close connection, since the statements feel like one thought and a full stop seems to overstate the separation
• •Conjunctive adverbs, since words like however and therefore feel like conjunctions and are not, so a comma before them creates a splice
• •Short clauses, since the join feels lighter when the pieces are small
• •Lists of parallel statements, where the writer treats sentences as list items
• •Translation habits, since several other languages permit the construction and writers carry it across

The construction appears throughout published literary prose and the writers using it are not making mistakes. It produces a breathless quality by removing the pause a full stop imposes, which suits urgency, accumulation and streams of impression. It marks a close relationship between statements that a full stop would sever. It is used in dialogue and in first-person narration to capture how people actually speak. And the short parallel version, listing brief clauses with commas, is a recognised classical figure that has been used for millennia. The difference between the effective and the incompetent version is control, since a writer who uses the construction deliberately in a text that otherwise punctuates conventionally is signalling something, while one who uses it throughout is simply not punctuating.

Since the semicolon is the standard remedy, it is worth being clear about what that mark does, because it is used nervously by many writers and avoided entirely by others. Its primary job is exactly this one, joining two independent clauses whose relationship is close enough that a full stop would overstate the break. Its secondary job is separating items in a list where the items themselves contain commas, which prevents the reader losing track of where each item ends. It does not introduce anything, which is what a colon does, and it does not mark a pause in the way a comma does. A useful test is that a semicolon can be replaced by a full stop without producing a fragment, and if the result is a fragment then the mark was wrong. Writers who avoid it entirely lose a genuine tool, and writers who scatter it produce prose that reads as fussy.

The prohibition is a convention of formal written English rather than a fact about the language, and its status is worth being clear about. It is not required by grammar in any deep sense, since the construction is used by competent writers and understood by every reader. It is strongly enforced in academic, professional and examined writing, where it is treated as an error and marked as one, and that enforcement is the practical reason to know the rule. Descriptive linguists point out that punctuation conventions are historically recent, have changed considerably and vary between languages and periods, which is true and does not help anyone whose work is being marked. The sensible position is to know the convention, follow it where the context expects it, and break it deliberately where the effect is worth it, which is the general approach to every rule of this kind.

Two clauses that could each stand alone, joined by a comma, which most readers of formal prose treat as an error. A full stop separates, a semicolon links as equals, a conjunction states the relation and subordination makes one serve the other, so the remedy depends on the meaning. Serious writers use the construction deliberately for pace and closeness, and the difference is control rather than the punctuation mark.