With three major varieties of conjunctions to have to memorize and juggle, we're all bound to get them confused from time to time. This page covers the most common mistakes writers at any skills level tend to make. When you think think you've adequately covered all of these issues, test how savvy you are about conjunction errors by completing the Conjunctions Exercise.
Coordinating Conjunctions:"But" or "Yet"?
Coordinating Conjunctions fall into three types: additive ("and"); selective ("or"); or, causal "for"). Each of these has an "anti-matter" counterpart that distributes the coordination in another direction: the selective "or" becomes "nor" to show the removal of choice; the causal "for" becomes "so" to show the effect of cause. The exception lies with the additive coordinating conjunctions, which have, not one, but two variations on the word "and." The conjunctions "but" and "yet" are closely related, and for that reason many writers treat them as if they're interchangeable--which they are not.
Consider the difference in the two sentences that follow:
In the first sentence, the use of the word "but" allows us to assume a great deal about what the sentence overall should mean. First, he believes that skydiving is a fun hobby, and he has accepted that it's an expensive hobby. From this, we might infer one of two conclusions: 1) he's not going to take up skydiving because it's too expensive; 2) he's going to take up skydiving fully capable of accommodating its expenses. There's no inherent conflict in either of these: one completely rejects the idea, while the other totally accepts the idea.
In the second sentence, the use of the word "yet" injects a degree of conflict into the sentence: he believes skydiving is a fun hobby, but he has not reconciled that it's an expensive hobby. From this, we can infer one of two conclusions: 1) he's not going to take up skydiving, upset by the fact that it's expensive; 2) he is going to take up skydiving, despite the fact that it's too expensive for him. An inherent conflict is at the heart of either of these: in one scenario, he feels bad that he can't take up the hobby; in the other, he feels bad that he can't afford the hobby he's already taken up.
When inherent conflicts like this occur in coordination, they create irony. Irony is an unexpected contrast or outcome. The coordinating conjunction "yet" should only ever be used to indicate this kind of irony. It cannot be used as a synonym for the word "but"!
"But" and "yet" have their counterparts as adverbs:
but = however; in contrast; dissimilarly
yet = regardless; in spite of this; unexpectedly
If you're ever confused about whether to use "but" or "yet," sometimes substituting these conjunctive adverbs helps to distinguish when one is more appropriate over the other. Confusing coordinating conjunctions with conjunctive adverbs, however, leads to another more serious error of grammar: sentence boundary errors.
Coordinating Conjunctions: "But Yet"
To make matters even more confusing, the word "yet" is also an adverb when used in another context:
In this example, you could easily be fooled into thinking that "but yet" are two coordinating conjunctions used side-by-side. They aren't. The word "yet" is an adverb modifying another adverb, "again." You can determine this by moving the adverbs further into the sentence:
Because coincidental pairings of coordinating conjunctions and the adverb "yet" confuse people, some take it to mean that the two coordinating conjunctions "but" and "yet" can be paired, as they coupling them intensifies the coordination.
This is not grammatically correct and should be avoided.
In compound sentences, coordinating conjunction distribute--or, coordinate--the relationship between or among independent clauses. A conjunctive adverb, on the other hand, creates a mood of transition at the start of an independent clause. You can see how closely related these two ideas are. However, that does not make them interchangeable. In fact, many transitional expressions are conjunctive adverbs.
The error occurs when writers treat conjunctive adverbs as though they're coordinating conjunctions, and use them with commas to splice together independent clauses. When that happens, a comma-spliced sentence occurs. To borrow a conjunctive adverb from above:
The word "however" in this sentence may transition to another clause with a mood of contrast, but it isn't a coordinating conjunction, so it shouldn't be preceded by a comma and treated as one. If we want a coordinating conjunction here, then the word "but" will do perfectly well enough:
If we want to retain the transitional tone of "however," then we'll either need to start a new sentence, or we'll have to change the comma to a semi-colon:
There remains yet one more grammatically correct solution to this problem: combining a coordinating conjunction with a conjunctive adverb:
This sometimes risks redundancy, especially if the conjunctive adverb and the coordinating conjunction mean the same thing. Redundancy can be mitigated if the conjunctive adverb is moved further into the sentence:
One of the most frequent examples of this sort of redundancy is the conjunctive adverb "still" paired with the coordinating conjunctions "but" and "yet," in which the pairing, itself, is treated as a single conjunctive adverb, or as a single coordinating conjunction--neither of which is permitted:
In the first example, "yet" and "still" mean precisely the same thing, so they are redundant. In the second example, a sentence fragment is the result, because the compound sentence has been broken at the conjunction. Either way you look at it, it's bad writing.
Semi-colons are a form of punctuation, not a part of speech. However, they do serve as a kind of implicit coordinating conjunction, since they join together three or more items in a series. "Series" in this case can be anything from clauses, to phrases, to individual words. Ordinarily, though, when phrases and words are joined together in a series, that series follows a colon [:].
When semi-colons join together two or more independent clauses, they create compound sentences. This is where the errors begin, because the semi-colon can be used only between independent clauses. Subordinate clauses, on the other hand, must be joined to their main clauses by a comma, never a semi-colon. Writers who have difficulty distinguishing between independent and dependent clauses will invariably stumble into this pitfall. For example:
In the example above, "whenever" is a subordinating conjunction and begins a subordinate clause. Since the semi-colon should join together only independent clauses, the result is a fragmented compound sentence. And a fragment is a major sentence boundary error. Either the semi-colon must be switched to a comma, or the subordinate clause must be built up into an independent one:
Furthermore, semi-colons should be used sparingly, when the coordinated relationship between two clauses is implicitly understood to the reader. This is as much a rhetorical effects as it is a semantic one, so overused semi-colons are as much an abuse of punctuation and rhetorical effect as the overuse of the exclamation point. When too many semi-colons are used to connect together different main ideas, the sentence becomes rambling:
Correlative Conjunctions always travel in pairs of phrases or clauses in parallel structures: structures that correlate, or "mirror," each other with equivalent parts of speech and word order. Therefore, both halves of a correlative conjunction must be balanced by the use of identical parts of speech in general word order. When they aren't balanced, we refer to that as "faulty parallelism."
The sentence above does not distribute equivalent parts of speech across the two halves of the correlative conjunction. If you removed the conjunction and let the two objects of it stand on their own, they are "He did know about the announcement" and "care about it," respectively. The first is a clause complete with subject and predicate, while the second is just a verb and its modifier. They don't mirror each other, then, in parts of speech and word order--by definition, faulty parallelism.
The faulty parallelism can be fixed in several ways, depending on how you want to distribute the objects of the conjunction into equivalent parts: