The short answer is no, you should not start a sentence with “but”. “But” is a coordinating conjunction that joins words, phrases, and clauses together:
The phone rang but no one picked up.
It is grammatically incorrect to start a sentence with a coordinating conjunction. This is especially the case in academic writing.
But there are exceptions to the rule. See what I did there?
Apart from academic writing and formal occasions, it is acceptable to start a sentence with “but” in speaking and in other types of writing.
To avoid run-on sentences and running out of breath, it makes sense to place a period at the end of a long, independent clause and start a new one with “but”. This also makes the new sentence sound more powerful.
Joanna reached for the doorknob but stopped. She knew perfectly well that her parents would be gone for the weekend and that no one would be home. But her instincts told her someone was behind the door.
Author: Katy Lia, Cambly Tutor
If you’d like to keep this conversation going with Katy, give her a call on Cambly or make a reservation with her here: https://www.cambly.com/en/student/tutor/Katy%20Lia