Every now and then, I come across someone with an aversion to that as a conjunction introducing a dependent clause. These folks strive to minimize the number of that’s in their writing, and do so by striking as many that’s as possible when editing.
These folks have good intentions. But they’re misperceiving the problem and, hence, applying the wrong solution.
My own style is, when in doubt, to use that or some other conjunction to introduce a dependent clause. The conjunction immediately informs the reader that what is to follow is a dependent clause. It thus makes the reader’s job easier because the reader then has less work to do in figuring out the sentence.
Sometimes if it’s short enough, a complex sentence doesn’t need a that to set off the dependent clause. Example: “She thinks he’s crazy.” But longer sentences with longer independent and dependent clauses usually need conjunctions like that to signal the dependent clause’s start and to show its relation to the rest of the sentence.
The problem with writing loaded with that’s is not that there are too many that’s, but that there are too many dependent clauses. If you’re bothered by a piece of writing with too many that’s as conjunctions, the solution is not to strike the that’s. All that does is make the writing harder for the reader to figure out. The sentences will be just as complex as they were before, only they will be harder to read, because they will lack the conjunctions to show the reader how the clauses relate to one another. Instead, try one of the following.
First, examine the that-containing sentence to see whether it’s doing too much work. It may be that some thoughts expressed in a dependent that clause deserve their own free-standing sentences. I’m not saying that all writing should consist of single-clause sentences or that all complex sentences should be banished. But lawyers are sometimes prone to writing convoluted prose, adding clause upon clause until they end up with a five-line monstrosity. When you break up a monster like that into smaller sentences, some dependent that clauses become free-standing sentences. You make the writing easier to read, and incidentally you reduce the number of that’s.
Second, examine the that clause grammatically to see what it’s doing in the sentence, and try to come up with a phrase or a single word that will do the same thing. Usually the that clause is modifying a noun or a verb, meaning it is functioning as an adjective or an adverb. But we don’t always need a full-blown clause to modify a noun or a verb—that’s what adjectives and adverbs are for! For example, instead of writing “skies that are blue,” write “blue skies.”
Also in your writing toolbox should be prepositional phrases and participial phrases, which also do the work of modifying a noun or a verb, but do so more efficiently than a full-blown dependent clause. When you convert a dependent that clause into a participial or prepositional phrase, you shorten and simplify the sentence, and (again) incidentally eliminate the need for a that.
For an excellent explanation of the right way to minimize that’s, read C. Edward Good’s A Grammar Book for You and I ... Oops, Me!, starting at page 242.