> In code or short tweets, fine, but in composition of an essay it looks unscholarly and pretentious. I think a good general rule is: for a single sentence, no

> In code or short tweets, fine, but in composition of an essay it looks unscholarly and pretentious. I think a good general rule is: for a single sentence, not capitalizing the first letter (and not using a period) is fine. Longer than that and it both makes parsing more difficult and looks strongly like an affectation. There is a practical purpose for sentence start/end punctuation.