How to Conince parents not to declaw?

Ok so im really against declawing, i have a really stubborn step dad, the reason why he tells me that he wants to declaw our 3 (15 1/2 week) month old kitten is because he says he will "scratch everything" our cat hasn't scratched anything or anyone ever since we got him except for his scratchers, and all he likes to do is nap, cuddle, sleep, and eat so whats the point?! He also said he has declawed every single cat he has had, i feel really bad, i want to do something, i don't want our new kitten to get declawed, i don't want his personality to change or anything. Help? Advice?