When I was at university, my English teacher used to insist a lot on the difference between these two expressions, telling us that even if was to be used when introducing a hypothetical situation (Even if I knew where John is, I wouldn't tell you), whereas even though was to be used as a concession or admission (Even though I know where John is, I won't tell you).
A few years have passed since my university days, and I'm under the impression that this kind of distinction is no longer made. Even if seems to be prevailing, and even though is less frequently found either in texts or in speech. Is my feeling correct? Has the difference between the two forms been cancelled?
Best Answer
I think what your English teacher told you is right, as far as it goes; but there is a middle ground it does not address, where either may be used. I imagine that very often this is what you are hearing.
The even clause may be neither hypothetical nor concessive but 'occasional'—that is, it may refer to a condition which is sometimes true and sometimes not. In such a case you might use even if or even though, because both are contextually equivalent to even when:
In formal contexts you would probably adjust these sentences a little to fit the conjunction more precisely:
But those are niceties which are not required in ordinary conversation.