Question
Why are Jewish children not named after someone who is alive?
Answer
This is an Ashkenazi custom that is not universally accepted (see Shu"t Yabiya Omer V Yoreh Deah 21 quoting Sefer HaChasiddim 420). There is an advantage in giving a baby the name of someone who has died since this is seen as giving satisfaction to the departed soul (Shu"t Yabiya Omer V Yoreh Deah 21).
