Great quote from Geoff Pullum at Language Log:
You know, just between you and me, I sometimes worry that there is a naive view loose out there — most students come to linguistics believing it, and there appear to be some professional linguists who regard it as central and explanatory — that language has something to do with purposes of efficiently conveying information from a speaker to a hearer. What a load of nonsense. I’m sorry, I don’t want to sound cynical and jaded, but language is not for informing. Language is for accusing, adumbrating, attacking, attracting, blustering, bossing, bullying, burbling, challenging, concealing, confusing, deceiving, defending, defocusing, deluding, denying, detracting, discomfiting, discouraging, dissembling, distracting, embarassing, embellishing, encouraging, enticing, evading, flattering, hinting, humiliating, insulting, interrogating, intimidating, inveigling, muddling, musing, needling, obfuscating, obscuring, persuading, protecting, rebutting, retorting, ridiculing, scaring, seducing, stroking, wondering, … Oh, you fools who think languages are vehicles for permitting a person who is aware of some fact to convey it clearly and accurately to some other person. You simply have no idea.