The quote "How did you know you're alive, unless you'd once been dead?" by Alan Watts seems like it uses the incorrect grammar. I would think instead of "you'd" it should be "you've", but perhaps I'm incorrect about this?
closed as off-topic by Marv Mills, Mitch, CDM, user140086, Brian Hooper Feb 5 '16 at 21:29
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "Proofreading questions are off-topic unless a specific source of concern in the text is clearly identified." – Marv Mills, Mitch, CDM, Community, Brian Hooper
Yes, it is a perfectly good English sentence.
The “you’d” (you had) matches the “did.”
English has conventions, not rules. So the context and location matters. The person you are quoting died almost 50 years ago, so you can expect the quote to sound antique. He was from the U.K. — so if you are not from the U.K. it may sound unfamiliar. And this is poetic writing, not conversational speech.
"How did you know you're alive, unless you'd once been dead?". The problem is 'did you know' which is a simple way of saying might/could/would you (have) know(n).
The sentence could be rendered (less confusingly?) as either of the following-
'How might/could/would you know that you were alive unless you had once been dead'.
'How might/could/would you have known that you were alive unless you had once been dead'.
In order for full tense agreement, it should be:
"How did you know you were alive, unless you'd once been dead?"
According to this other ELU question, "you're" cannot be short for "you were".