Is this a semicolon or not?

Question

Here's an example.

You know, I'm not sure what I want to do; but the doctor recommended I have the surgery.

Answer 1

You would not use a semicolon here, because the "but" makes the second half of the sentence a dependent clause. A semicolon is used to combine two independent clauses into one sentence. If you take out the "but," you can use a semicolon.

You know, I don't know what I want to do, but the doctor recommended that I have the surgery.

You know, I don't know what I want to do; the doctor recommended that I have the surgery.

For a colon, the second clause would have to provide further details about the first. I would not say that is the case here.

Note: the "you know" is pretty casual. It's fine if this is dialogue, but in formal writing I would not use it.