You do not settle whether an argument is justified by merely showing that it is of some use. The distinction is not between useful and useless experiments but between barbarous and civilized behaviour. Vivisection is a social evil because if it advances human knowledge, it does so at the expense of human character.
It is necessary for the welfare of society that genius should be privileged to utter sedition, to blaspheme, to outrage good taste, to corrupt the youthful mind, and generally to scandalize one's uncles.
There is nothing on earth more exquisite than a bonny book, with well-placed columns of rich black writing in beautiful borders, and illuminated pictures cunningly inset. But nowadays, instead of looking at books, people read them. A book might as well be one of those orders for bacon and bran.
The fact is that the intrinsic worth of the book, play or whatever the author is trying to sell is the least, last factor in the the whole transaction.
The popular definition of tragedy is heavy drama in which everyone is killed in the last act, comedy being light drama in which everyone is married in the last act.