This request comes from Libro’s very own technical support department, otherwise known as Matthew. I don’t think it’s something he confuses himself, but he’s seen the confusion in action. Please feel free to submit your own suggested pairs to me as we go along, although it’s worth checking the list of all the posts here before you do that.
Anyway, on to assume and presume. Which have quite a subtle distinction.
To assume is to accept something as true without proof.
To presume is to suppose that something is the case on the basis of probability, or to take for granted.
So if you assume something is going to happen, you don’t have any proof and there may well not even be a probability that it is going to happen, whereas if you presume it’s going to, there is at least a probability that it will, or it has done in the past and you’re working from that.
Subtle? Yes. Clear? You tell me!
You can find more troublesome pairs here.