Comma splice explained, or how to connect sentences in English?

Simple Rules

• Comma splice: Connecting two phrases that can be sentences with a comma.
• Correct way: Use a semicolon.

Simple Examples

• Wrong: I washed the dishes, she cleaned the house.
• Correct: I washed the dishes; she cleaned the house.

Quick Rules

• Comma splice: It’s a grammatical mistake to connect two independent clauses with a comma (called a comma splice).
• Correct way: Use a semicolon.
• 4 acceptable alternatives to semicolon:
  1. Full stop or period.
  2. A comma with coordinating conjunction (and, or, but so, yet, nor, for).
  3. Colon.
  4. Dash.
• An independent clause is any clause that can stand by itself as a complete sentence. It must:
  • Have a subject (noun or pronoun).
  • Predicate (verb or implied verb).
  • Express a complete thought.

Quick Examples

• Wrong: I washed the dishes, she cleaned the house.
• Correct: I washed the dishes; she cleaned the house.
• Correct (alternative 1): I washed the dishes. She cleaned the house.
• Correct (alternative 2): I washed the dishes, and she cleaned the house.
• Correct (alternative 3): I washed the dishes: now they are clean.
• Correct (alternative 4): I washed the dishes – she cleaned the house.

Full Rules

In English, unlike many other European languages, including German, French and Russian, a comma splice, or connecting two independent clauses with a comma, is considered a mistake.

An independent clause is any clause that has a subject (often noun or pronoun), predicate (action of the noun, often a verb) and can stand by itself as a complete sentence (expresses a complete thought).

It’s very tempting, and sometimes feels completely natural, to connect or splice two sentences with a comma, especially when writing in a stream-of-consciousness manner or coming to English writing from a foreign language background. Nevertheless, it is a mistake in English. There are, however, a few correct alternatives:

1. Semicolon: Connect two independent clauses with a semicolon. The closest alternative to a comma splice but can look a bit formal.
2. Full stop: Simply put a full stop, and make two sentences. Most neutral way of writing.
3. Comma with coordinating conjunction: Connect two independent clauses with a comma and coordinating conjunction (and, or, but, so, yet, nor, for). Another neutral way of writing but can make a sentence wordy.
4. Colon: Connect two independent clauses with a colon. Considered formal and implies dependence of one clause on another.
5. Dash: Connect two independent clauses with a dash. Considered informal and usually implies some relationship between two clauses. Dashes are best avoided in formal writing.

Full Examples

Wrong

• I washed the dishes, she cleaned the house.

Correct

1. Semicolon: I washed the dishes; she cleaned the house.
2. Full stop: I washed the dishes. She cleaned the house.
3. Comma with coordinating conjunction: I washed the dishes, and she cleaned the house.
4. Colon: I washed the dishes: now they are clean.
5. Dash: I washed the dishes – she cleaned the house.

Exceptions

For non-English speakers the comma splice rule seems a bit contradictory, as writing is full of examples where people use comma splices. For the most part, this is simply an incorrect usage, but there are few exceptions that can warrant a splice:

1. To give a sentence light, informal, conversational tone. Use this in informal emails or communications between friends.
2. Literary usage when the clauses are short and very closely related.

Examples

1. Don’t worry, I am on it.
2. I think, therefore I am.

Final Note: Conjunctive Adverbs

Conjunctive adverbs – e.g. however, nevertheless, therefore, thus, etc. – are not coordinating conjunctions when they connect two independent clauses. Connecting two independent clauses with a conjunctive adverb is also a comma splice. Therefore, same comma splice rules apply to them.

Examples

• Wrong: I worked hard today, however I did not finish my work.
• Correct (1): I worked hard today; however, I did not finish my work.
• Correct (2): I worked hard today. However, I did not finish my work.
• Correct (3): I worked hard today, and therefore I finished my work.
• Correct (4): I worked hard today: therefore, I finished my work.
• Correct (5): I worked hard today – however, I did not finish my work.