Exactly!The only person who can answer that question is Philip K. Dick...............
I've read the book at least three times, and the last time I paid close attention specifically to the Deckard question. I firmly believe (in the book) he was human all the way, and a sad human at that. Ridley Scott "interpreted" the book (as most Directors do) , left out half the story (Mercer) and asked a different question about "humanity". I enjoy Scott's vision, but it is not quite the same as Dick.Exactly!