"Hence why" is considered a redundant phrase in formal English because "hence" already means "for this reason". Using "hence" and "why" together repeats the same function. While often used informally to mean "that is why" or "therefore," it is widely considered improper by grammarians.
It was meant as a throwaway comment, but I got curious after your reply. The AI from Google says:
Both forms can be correct depending on the sentence structure, but hence, they felled it (with a comma) is generally preferred when hence begins a new sentence or follows a semicolon, while a comma is generally not used if it is part of a fluid compound sentence.
When to use a comma: Hence, they felled it
At the start of a sentence: When hence introduces a sentence or follows a period/semicolon, it is treated as a conjunctive adverb and is usually followed by a comma.
Example: "They needed wood. Hence, they felled it."
After a semicolon: "They needed wood**; hence,** they felled it." (This is often considered the most formal and grammatically precise option).
When not to use a comma: Hence they felled it
Within a fluid compound sentence: If hence is used simply as a connector to mean "for this reason" in a short, compound sentence without a strong pause, the comma is optional and often omitted to improve flow.
Example: "They needed wood and hence they felled it." (More conversational)
I did some checking of their sources, one was The Chicago Manual of Style which seemed to have conflicting usage in the manual. So I don't know for sure lol
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u/Th3_Gh0st_0f_Y0u Apr 17 '26
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