Last summer Simon Heffer, associate editor of the Daily Telegraph, fired off an email rebuking his colleagues for their linguistic slovenliness and ignorance. He took them to task on a number of counts, including inconsistencies, malapropisms, confused homophones, Americanisms and grammatical errors.

Reading his litany of complaints, my eye was drawn to a paragraph that began: "Sometimes we do not properly think of the sense of what we are writing. There is a marked difference between the meanings of convince and persuade that is not recognised by some of you. If you are unsure of the distinction, look the words up."

My first response was embarrassment. If I am honest, the distinction between convince and persuade was not one I had ever thought about. Despite being an enthusiastic devourer of English usage books, I could not recall ever having come across an entry on the "marked difference" between these two verbs.

Reading Heffer's pronouncement had a Proust-dipping-his-madeleine-in-tea impact on me. I was whisked back to an austere grammar school classroom where my English teacher, Chalkie White, was handing me back a piece of homework covered in red ballpoint.

I had incurred Chalkie's wrath because I had used the word "simplistic". My sin was twofold: first, I had strayed into the vernacular and returned bearing a non-word; and then I had been foolish enough to use it in a piece of formal writing. Chalkie's response was swift and surgical. My original had been obliterated by his red pen, and in the margin were the words: "simplist, one who gathers herbs – adjective, simplistic".

My anecdote seems quaint because nowadays "simplistic" is part of the linguistic furniture. But as a young lad from a modest background struggling to keep my head above water in a grammar school, the incident had a devastating effect on me: for many years, it made me wary of colloquial language – as well as undermining my faith in my own linguistic judgment.

In those far-off days, linguistic authority was in the hands of a hieratic elite of lexicographers and grammarians whose sacred texts were the Oxford English Dictionary and handbooks of English style and usage. If my definition of "simplistic" was not in the dictionary, it did not exist. (In fact, the OED states that the modern meaning of the word dates back to the 19th century, but at the time of the incident the Concise version did not record this.)

This is the line taken by Heffer in his recent book, Strictly English, where he asserts that "rules in language are made by logic, not by a democratic vote". But this view of how language evolves is anachronistic; things have changed a great deal since the prescriptivism of Chalkie White's day. Take a look at these reviews of Heffer's book by a couple of distinguished modern linguists – David Crystal and Geoff Pullum – if you have any doubts.

For Heffer, however, language remains the site of a battle between a priestly caste and the barbarians at the gate. But is he right to insinuate that journalists who fail to observe the difference between convince and persuade should hang their heads in shame?

As I have confessed, I was blind to the distinction, so I began by asking my Twitter followers if it meant anything to them. The results were fascinating and instructive. Fascinating because of the emotional heat generated, and instructive because the explanations proffered were so varied, and sometimes contradictory.

Here are some of them: "Does 'to be persuaded' imply that a greater change of heart/mind is required than 'to be convinced'?"

"For me, 'to persuade' implies the changing of minds, 'to convince' the dispelling of doubts."

"They feel different to me. How about this: you persuade someone to do something; you convince someone of something."

"I've always seen convince as more concrete/overt; persuade as more machiavellian. Convince by argument, persuade by appeal. Or to put it another way, an argument could be persuasive but not convincing if it was appealing but lacked some hard evidence."

With my head spinning, I reached for some reference books. The 19th-century scholar Richard Grant White – whose views on the subject shaped the 20th-century debate – begins by reminding us that the use of persuade to mean a change of mind is well established in the King James Bible and the works of Shakespeare. Undeterred, however, by historical precedents, White advances an eccentric etymological argument for the idea that people are sometimes persuaded to act against their conviction; he was of the opinion that the realm of changed minds should be the exclusive province of convince.

White's influence can be seen in an explanation put forward by Bill Bryson, who states that you convince someone they should believe something, but persuade them to carry out an action – and he declares it is possible to persuade someone to do something without convincing them of the correctness or necessity of doing it. He also alerts us to a grammatical difference: persuade may be followed by an infinitive, but convince may not.

The Merriam-Webster Dictionary of English Usage asserts that persuasion involves a change of belief followed by action – an explanation at odds with Bryson's. Merriam-Webster's entry concludes: "Long ago persuade became established in a use connoting mental acceptance without following action … Persuade still has this use, often with same of and that constructions regularly found with convince. Some time around the middle of the [20th] century, convince began to be used to connote mental acceptance followed by action, usually in a construction in which an infinitive phrase follows the verb. This construction is now a fully established idiom. The earlier usage writers who tried to fence off persuade from convince and the later ones who tried to fence off convince from persuade have failed alike. And in another generation perhaps no one will care."

This entry, which dates from 1994, was prophetic: everything it predicted has come to pass. Two years after its publication, an overwhelming majority of the usage panel of the American Heritage Dictionary accepted the use of convince with an infinitive; and even the current online OED entry accepts that the usage "is well established".

In this instance – where the horse has already bolted – Heffer's logical approach draws a blank. He is mistaken, however, if he thinks the alternative, linguistic democracy, ends in a linguistic free-for-all. In fact, given the inconsistent evidence I have uncovered, I would argue that the wisdom of crowds has been vindicated because it has replaced pernickety – and inconsistent – distinctions with clarity.

An acceptance of linguistic democracy – as reflected in everyday usage and the corpus – does not mean that those of us who care about language should not take a logical stand on particular points of usage. But the points we choose to defend need to have some life left in them, and the evidence that supports them must be compelling. For example, whenever I hear someone use infer when they should be using imply, I experience a thump in the solar plexus. But I am fortunate because, for the time being at least, dictionaries and books on usage supply me with unambiguous ammunition in my efforts to argue in favour of their difference.

The linguistic battlefield is heaped with ancient carcasses, so it is vital to focus our efforts on the living. There comes a moment when you have to accept that some usages are dying or dead. If I were a betting man, I would probably put a few quid on the distinction between infer and imply going the same way as that between convince and persuade; but I while I detect the faintest of pulses, I will keep treating the sick and wounded.

Martin Shovel blogs at CreativityWorks.net