Thinking yesterday about the question of whether or not we can use in and out together, and about phrasal verbs, made me think of something else. Have you ever noticed that fill in and fill out mean the same thing?

At least they do when they’re being used in relation to a form anyway. It’s strange of course, because in and out are usually the opposites of each other. And more specifically, it’s strange because with phrasal verbs like fill in, fill out, and stay in, we often form the opposite of  by using the opposite adverb with the same verb. Switch on and switch off, for example, or tune in and tune out. You’d expect then, that the opposite of fill in would be fill out, but we’ve seen before how apparent opposites in English are never as simple as they seem. A phrasal verb, by the way is a verb combined with a second word, usually an adverb, that together have a unique meaning, usually quite different from the verb on its own.

Of the two, fill in seems more logical. If you’ve got a form, it has blank spaces which you have to fill by putting information in those spaces. Fill on its own wouldn’t work, not in reference to the form as a whole. You fill the spaces, sure, but filling a form would feel like you were covering every last millimetre of the form with ink. And that’s probably not what you’re supposed to do.

So what about fill out then? First of all, it seems like it’s used more often in American English than British English. Searching the Corpus of Contemporary American EnglishCorpus of Contemporary American English provides more results for fill out a form than fill in a form. This may be a result of the influence of German-speaking immigrants on American English, as the German phrase ausfüllen can be directly translated to fill out. I’ve tried checking the British National Corpus, but it’s not working as of time of writing. Anecdotally though, it seems fill in is more common in British English. Here in Ireland we tend to use both, as we’re exposed to both British and American English quite often.

Thinking now actually, even though fill in might seem more logical, fill out also seems kind of logical. It makes sense in terms of filling out a whole form, as the out conveys a sense of expansiveness, probably related to the concept of outside that goes along with it. For a lot of people, I think it makes sense to say fill out a form, but perhaps fill in a specific section of a form. That’s probably why, when we want someone to give us information, we tell them to fill us in. We want them to put this specific information in our mind, like when we fill in a particular section of a form. Fill us out just wouldn’t make sense in that context.

Luckily for most of us, we don’t need to really worry about all of this. We can use either one, and no-one gets confused. But phrasal verbs like these are very confusing for learners. Often their meaning is not clear. Fill in/out isn’t so bad because they’re still related to the idea of filling, but think about how we say a plane takes off. What does that have to do with taking? And then we can say a business idea or fashion trend is taking off. Native speakers have no trouble with such phrases, but they’re very hard to learn, because there’s no apparent logic to them. And then when get into opposites, all bets are off. You put on your clothes in the morning, so logically then at night you put them off. What? It’s take off? Oh, ok. And put off actually means postpone? Right…

You can see just how difficult English is to master. Using phrasal verbs well is one of the main steps towards being proficient, but a lot of English learners never get to that point. Usually, there’s a verb you can use instead. You could say you remove your clothes at night, which works, but doesn’t sound very natural, does it? Which is why a lot of people never bridge the gap between being a very good English speaker, and proficient. If you’re a native speaker then, take a moment now and then to listen to yourself and notice how many phrasal verbs you use, and imagine how hard it would be to learn them.