Talking about function, purpose, and method in English: Part 1

It can be tricky to figure out which structure to use when talking about how to do an action, why an action is done, or what tool can be used to do an action, so in this article I’d like to introduce 4 structures for talking about these situations in English (using for, to, by, and with).

In Part 1, we'll look at using “for + (gerund)” to express function and “(in order) + (infinitive)” to express purpose.

1. When describing the basic function of something, you can use “for + (gerund).” This structure focuses on a tool/object and explains what it is for (its function).

Obvious examples are “Pens are for writing” and “Phones are for calling and texting people,” but in reality this structure is more often used to describe the function of something that is unfamiliar, such as “This machine is for grinding cocoa beans” or “That button is for restarting the whole system.”

You can use “for + (gerund)” to express the intended function of something, but if you want to talk about an unintended (creative) function, you can say the following:

Ex. Normally, paint brushes are for painting, but you can also use them to dust things, like keyboards! (use + (object) + (infinitive))

And yes, I do use an old watercolour brush to dust my laptop keyboard! It works very well!

2. When expressing the purpose of an action, you can use an infinitive of purpose “(in order) + (infinitive).” This structure focuses on explaining “why” an action was taken. (The words “in order” are often left out.)

Ex. We looked online (in order) to find some instructions.

Ex. The government has decided to invest a significant amount (in order) to replace the old infrastructure.

Note: Avoid using “for + (gerund)” in this case, which is a common mistake!

Ex. I went over to the bank for getting some cash. (incorrect)

Ex. I went over to the bank to get some cash. (correct)

It is also sometimes possible to express the purpose of an action with “for + (noun).”

Ex. He went out for milk. (= He went out to get milk.)

Next time, in Part 2, we'll look at ways to talk about the method of doing something and the tools than can be used to do something.