QUESTION: Which is correct to say? I go do something / I go to do something.
ANSWER: A YouTuber stumped me with this question. My response to the viewer began with a comparison between in order to and the use of the infinitive to express purpose.
Consider these examples:
I went upstairs to wake up my sister. / I went upstairs in order to wake up my sister.
= Why did I go upstairs? Short answers:
To wake up my sister. / In order to wake up my sister.
In everyday speech, we favor the infinitive over in order to. It’s quicker and easier to express the purpose of action.
I then moved on to examples that made no use of infinitives.
Consider the sentence: I went upstairs and woke up my sister.
The example above is basically the same as the first two examples, but it’s written as a sequence of actions. First, I went upstairs. Then, I woke up my sister. The sense of purpose isn’t emphasized. From this point of view, you can understand the request: “Please go upstairs and wake your sister up.” The request is correctly worded, but is it truly necessary to mention exactly where the sister is? Not really, so a parent might ask simply: “Please go (and) wake your sister up.” In spoken English, you can say “go wake her up” OR “go and wake her up”. Both ways it’s understood that the purpose of going is to wake her up. Note: It would sound unnatural to ask: “Please go upstairs (in order) to wake your sister up.”
As I give more thought to this matter, I find myself making a distinction between expressing an intent and expressing a purpose. It seems that go do is suited for requests and statements of intent and go to do is suited for statements of purpose:
Please go visit your grandmother. [request]
I need to go visit my grandmother. / I must go visit my grandmother. [statement of intent]
I went to visit my grandmother. [statement of purpose]
Would you agree with my conclusions?