We have mentioned once before the “AI assistant” that works in Zoho Writer to give you “grammar, readability, and style suggestions to further polish your piece.” If you begin a sentence with the word “But,” here is the advice you get:

But → However

Conjunction at the beginning of a sentence

Though not grammatically incor­rect, using conjunc­tions like and, or, or but at the beginning of a sentence is not recommended in formal writing. It tends to make sentences sound more dramatic.

We have acci­dentally come across the golden key that opens up “formal writing” as a style. Beginning sentences with con­junc­tions is not recom­mended because it sounds more dramatic. Formal writing, then, must be writing whose purpose is specif­ically not to engage the reader’s atten­tion. It is very impolite to wake up your readers with a jolt while they pass over your words with un­focused eyes. We use “formal” style specif­ically to prevent com­muni­cation from happening. Substitute “however” for “but” and let your readers get back to their naps.

If, however, Zia the AI assistant were really on the ball, she would point out that “however” also ought not to begin a sentence if we wish to main­tain a strictly formal style.