From the Grammarphobia blog.
Q: In a recent radio appearance, you said the idea that “he” can refer to any human being – man or woman – was introduced in the 18th century by a female grammarian. I think you’re wrong. The concept of male as universal has been around much longer.
A: If by “male as universal,” you mean using male pronouns (“he,” “him,” and “his”) for women as well as men, the idea did indeed begin in the 18th century.
Before then – for two centuries, in fact – it was considered acceptable to use “they,” “them,” and “their” as singular or plural pronouns for either men or women.
Anne Fisher, the first woman to write an English grammar, was also the first grammarian to suggest that the pronoun “he” be used generically for either sex.
In the mid-18th century, she proposed that “he” be a sex-neutral, third-person singular in cases where gender was indefinite. For example, on second reference to “someone,” “anyone,” and so on, as in “Does anyone think he knows the answer?”
There’s no surviving copy of the first edition of Fisher’s book, A New Grammar With Exercises of Bad English, but it was advertised for sale in 1745. It was followed in 1750 by a second edition (which we do have), and 30 more editions came later, making the book one of the most popular guides of its time.
One reason her book is so important historically (there are other reasons, too) is its suggestion that “he” and company be used as a blanket term for both sexes.
“The Masculine Person,” Fisher wrote, “answers to the general Name, which comprehends both Male and Female; as, any Person who knows what he says.” [continue]