I spend a lot of time thinking about English; specifically, how dogmatic one should be? How does one know when to balk at and when to embrace a change in the language? This quotation from Bill Bryson's The Mother Tongue: English And How It Got That Way has some good common-sense advice:
"One of the undoubted virtues of English is that it is a fluid and democratic language in which meanings shift and change in response to the pressures of common usage rather than the dictates of commmittees. To interfere with that process is arguably both arrogant and futile, since clearly the weight of usage will push new meanings into currency no matter how many authorities hurl themselves into the path of change.
"But at the same time, it seems to me, there is a case for resistng change–at least slapdash change. Even the most liberal descriptivist would accept that there must be some conventions of usage. We must agree to spell cat c-a-t and not e-l-e-p-h-a-n-t, and we must agree that by that word we mean a small furry quadruped that goes meow and sits comfortably on one's lap and not a large lumbering beast that grows tusks and is exceedingly difficult to housebreak. In precisely the same way, clarity is generally better served if we agree to observe a distinction between imply and infer, forego and forgo, fortuitous and fortunate, uninterested and disinterested, and many others."