„The rule that you not use words that were first uttered or written by  another without due attribution is less like the rule against stealing,  which is at least culturally universal, than it is like  the rules of  golf.  I choose golf because its rules are so much more severe and  therefore so much odder than the rules of other sports.  In baseball you  can (and should) steal bases and hide the ball. In football you can  (and should) fake a pass or throw your opponent to the ground. In  basketball you will be praised for obstructing an opposing player’s view  of the court by waving your hands in front of his face. In hockey …  well let’s not go there.  But in golf, if you so much as move the ball  accidentally while breathing on it far away from anyone who might have  seen what you did, you must immediately report yourself and incur the  penalty. (Think of what would happen to the base-runner called safe at  home-plate who said to the umpire, “Excuse me, sir, but although you  missed it, I failed to touch third base.”)
Golf’s rules have been called arcane and it is not unusual to see  play stopped while a P.G.A. official arrives with rule book in hand and  pronounces in the manner of an I.R.S. official. Both fans and players  are aware of how peculiar and “in-house” the rules are; knowledge of  them is what links the members of a small community, and those outside  the community (most people in the world) can be excused if they just  don’t see what the fuss is about.
Plagiarism is like that; it’s an insider’s obsession.  If you’re a  professional journalist, or an academic historian, or a philosopher, or a  social scientist or a scientist, the game  you play for a living is  underwritten by the assumed value of originality and failure properly to  credit the work of others is a big and obvious no-no.  But if you’re a  musician or a novelist, the boundary lines are less clear (although  there certainly are some) and if you’re a politician it may not occur to  you, as it did not at one time to Joe Biden, that you’re doing anything  wrong when you appropriate the speech of a revered statesman.”