Challenge posed in an email from Stense:
…I spent yesterday musing about why I thought 'If I were you' was more grammatically correct than 'If I was you' - answers on a postcard please!
An excellent challenge! So I sent her a post card (printed in very small letters), which went as follows:
You asked for answers on a post card for why you (correctly) thought 'If I were you' was more grammatically correct than 'If I was you'. The answer is that you are employing the subjunctive, i.e. you have changed the form of a verb when the content of the clause in which it is contained is being doubted, supposed, feared true, etc., rather than being asserted. It's the word 'if' that's the dead give-away... You are raising the hypothetical supposition that you could be me and choose to act differently to me. English isn't the only language that has a subjunctive (s/t)ense (ouch!). I learnt all about the subjunctive in my Latin lessons, and it's a very useful weapon to have in your arsenal. If we didn't have the subjunctive, how would we be able to tell whether 'if I was you' meant 'supposing I was in your position' or meant 'if I used to be you'? (Although, if you'll forgive a somewhat pedantic aside, the latter doesn't make much sense in a world where people do not swap personalities. Indeed, the fact that we do not swap personalities renders the phrase 'If I were you' completely preposterous - for I shall never be you, and, even if I did miraculously manage to become you (and could somehow resist the overwhelming temptation to take a hot, soapy shower before covering myself in baby oil), I would still do exactly the same as whatever you would do in that situation - because I would actually be you!)
But, having said all that, note how I failed to employ the subjunctive in the phrase 'If we didn't have the subjunctive, how would we be able to tell...' above. By rights, I should really have said 'how should we' and not 'how would we', for I was exploring the hypothetical situation in which the subjunctive did not exist. You see how tricky the subjunctive can get? Indeed, so tricky is it that I'm not entirely sure that it shouldn't have been 'how would we' all along.
Unfortunately for those like me who had the benefit of a classical education, and who tend to appreciate this sort of arcane mumbo-jumbo, the use of the subjunctive has gone into a steep decline in recent years - or, to put it another way (look out, Stense, here comes the pun:) the world seems to be suffering from a severe bout of subjunctivitis.
I hope that answers your question - although perhaps it would be simpler for me to email a reply next time.