There’s a dubious rule in English that you’re not supposed to use an adverb (usually a word ending in –ly) to set up the attitude or meaning of a sentence. Here’s an example of what you supposedly shouldn’t do:
Hopefully, tomorrow’s weather will be perfect for our picnic.
Tomorrow’s weather can’t do anything hopefully, and that makes the sentence wrong. So say the grammarians.
But James Harbeck (a linguistics expert I like very much) convincingly argues against this nonsense in his Sesquiotica blog: https://sesquiotic.com/2014/09/09/seriously-whats-the-problem-with-sentence-adverbs/
His blog offers three examples of sentences that break the rule about adverbs – without a single peep of protest from the grammarians:
Seriously, it will be very amusing.
Frankly, you’re being evasive.
Clearly, someone has muddied the water.
This tempest-in-a-grammatical teapot reminds me of the people who say that you can’t end a sentence with a preposition. Five minutes later they’re happily talking about putting their shoes on, turning the TV off, inviting the neighbors over, and letting the dog out.
And then there are avid readers who think you can’t start a sentence with but, even though every book they’ve ever read has sentences starting with but on almost every page.
Years ago I heard an authority on English say that our language doesn’t have any grammar. I wondered then (and still do) what he meant and whether he was right. I still haven’t come up with satisfactory answers.
But (ha!) what I have decided is that grammar is always secondary. Experts study the language, watch what it does, and then extrapolate grammar rules. So far, so good.
But there are always a couple of experts who want to flip this sensible system around. They insist on making the rules first and then forcing the language to fit – even if it’s a tight squeeze.
Not every self-proclaimed expert knows what they’re talking about. Beware! Watch what the language does, not what someone thinks it should do.