How to Make Sense of Whether to Use “Since” or “Because”

If you’ve ever asked yourself if would be more correct to say, “Since I don’t feel well, I shouldn’t go to work today,” or “I shouldn’t go to work today because I don’t feel well,” you’ve come to the right place. Since and because are another of those pairs of English words that seem like synonyms, but we’ve sensed (or been told) there is a proper time and place to use each one.

I have a vague recollection of being taught at some point during my journalistic training that since is to be reserved only for when I’m referring to time (I haven’t been feeling well since last night) and because was to be reserved for references to causation (I don’t feel well because the meat was spoiled). But the most recent school of thought is that since can be used to refer to either time or cause — as long as using it doesn’t make the meaning of a sentence ambiguous.

Why we might want to choose one over the other

Without even realising it, we may be naturally choosing one or the other as a conjunction based on whether we want to focus on the result of something or the reason behind it. Here’s what the Cambridge Dictionary says about using “because”:

Because is more common than as and since, both in writing and speaking. When we use because, we are focusing on the reason:

She spoke quietly because she didn’t want Catherine to hear.

We’ll come over on Sunday because David’s got to work on Saturday.

On the flip side, if we want to focus more on the result of the thing, since may strike us as the better choice. Since the food is so good, it’s hard to get a reservation there.

Still, this is a matter of preference if you want to try to give either the reason or the result a bit of extra emphasis — it’s not an actual rule.

Situations to avoid

Most of the time, the person you’re talking to (or who is reading your words) isn’t even going to notice whether you’ve dropped a “since” or a “because” — or even the less common, “as.” (It’s time to go, as we’ve overstayed our welcome.) Your meaning is usually clear, and everyone can move on.

What you want to watch out for, though, is the occasional ambiguity since can cause if it’s unclear whether it is referring to time or to cause. Consider this example from Brian A. Klems at Writer’s Digest:

Since we had breakfast, we were filled with energy.

This lets you wonder, were we filled with energy because of breakfast or just after breakfast?

So, in short: Your usage of because is probably always correct. If your usage of since isn’t confusing (and it probably isn’t), then that’s correct, too.