Grammar: Does the word 'so' need a comma in front of it?

So I just learned a neat trick for figuring out whether or not so needs a comma in front of it. Just pop the clause it begins in front of the sentence and, if it’s nonsensical, no comma.

In other words, if the so only meaningfully fits between the two clauses it joins, then that’s a coordinating conjunction. But, if the so clause works at the beginning, predicting something because of something else, for example, it's acting like a subordinating conjunction, so no comma is needed. (Note that the article on Grammar Girl, linked below, never actually says it is a subordinating conjunction. It just says that it acts like one.)

Another thing I noticed was that most of the subordinating-like instances hide an invisible that right after so (or close, such as in so long that), so if you can insert a that in the clause, you probably don’t need the comma. Fun, huh?

So, to recap, if you find a so you're unsure of, move its clause to the beginning or insert a that right after it. If either action makes it sound weird, then so is a coordinating conjunction in that case, and you need a comma.

Examples:

He wanted to go to the party, so I went with him.
Doesn't make sense if you say: So I went with him, he wanted to go to the party. In this case, so is a coordinating conjunction.

He told me there would be a snack bar at the party so I would go with him.
Here you could state this as, "So I would go with him, he told me there would be a snack bar at the party." That makes sense, so you would treat it like a subordinating conjunction, no comma. It also passes the insert that trick: He told me there would be a snack bar at the party so that I would go with him.


Here are a couple of grammar articles I found helpful with regard to so and other conjunctions. The Grammar Girl one was my primary reference for this post.

Grammar Girl: Weird Coordinating Conjunctions: Yet, For and So

 

Grammar Bytes: The Coordinating Conjunction--Recognize a coordinating conjunction when you see one.

Are you the victim of human auto-correct?

Do you find yourself sending an email only to notice glaring errors only moments later? Do you hit publish or post, only to find comments about your grammar, or lack thereof, sprinkled throughout subsequent comments and reviews? If so, you may be the victim of human auto-correct.

The human brain is a wonderful thing. It helps us make sense of a chaotic world and helps us react accordingly; but, similar to the auto-correct on your phone, the brain also subconsciously hides, or auto-corrects, inconsistencies, errors and omissions we encounter in the written word. A duplicate word becomes invisible, a misspelling is overlooked, and missing words are filled in.

Surely, you've seen blurbs where almost every word is a jumble of letters, but you were able to read the message anyway. Take the following example.

The qicuk bworn fox jmups oevr the lzay dgos.

You probably read this with no problems. In fact, so long as the first and last letter of a word is in place, most people's minds will substitute the correct word, especially if there's context to go with it.