When I use the word “obvious” or “obviously”, it’s always a contraction for “this is obvious to me”.
I mean to convey smth like “I’ve read/… a lot about this subject and what you said was comparatively early on in my learning-journey, so at this point this is quite obvious to me.” or “I’ve already thought about similar things a lot and this is a conclusion I have come to a lot of times already.” or “I’m deep enough in the subject matter that I can jump to all the implied inferential steps automatically.”
To go into it more deeply:
“That’s obvious” in itself is an incomplete phrase, like “larger than”, it needs a subject. The default subject here might be “to everyone”, or to make it more realistic “to most people” or “to almost all non-children”, but this phrase-completion seems
- less useful: it quickly conveys that what was said was really not necessary to be said. But not to the listener specifically, but that basically everyone would not have benefited from what was said. I just don’t think that this comes up often enough as that we need a short-hand for it.
- and lends itself too much to ill-spirited usage: “that’s obvious [to basically everyone]” is an easy way to make someone else feel bad
- or even to make oneself seem superior by implying that one is so smart/… that one typical-minded “that’s so incredibly obvious to me, it must be obvious to everyone, surely”, a faux-misunderstanding that’s easy to deny.
What makes “obviously” such a useful word is its conversation economy. If two people are having a factual conversation and one person is describing or explaining something, then having a very quick way to signal something along the lines of “thanks, I have actually been coming across what you just said a while ago, so this isn’t new information to me. Furthermore, I agree with what you said and would just like to move on instead of lingering on this point” is incredibly useful to keep the conversation flowing and get to the interesting bits sooner.
And phrases like “for sure”1, “of course”2, and “obviously” are – I claim – good for this, with the last one feeling like the strongest version in terms of “I really understand what you’re saying, let’s really move onwards in the conversation”.