Who's right? I'm not trying to duck by saying both are, and that these two passages are not necessarily in conflict. What I mean is that the purpose of copyright is (as Yglesias says) to encourage creation of works -- by (as Bunch says) "protect[ing] the intellectual property created by artists so they are rewarded for their efforts." But what's important isn't what I think; what really matters is what Justice Ginsburg, joined by six other members of the Supreme Court, said in footnote 18 of Eldred v. Ashcroft, 537 U.S. 186 (2003) about this very subject:
The purpose of intellectual property law has very little to do with Matt Yglesias being able to enjoy a wide variety of new music. The purpose of intellectual property law is to protect the intellectual property created by artists so they are rewarded for their efforts. The purpose of intellectual property law is to punish people who steal that which isn’t theirs.
The point of intellectual property law is to benefit consumers, not producers. I don’t really want to turn this into an ideological food fight, so I’m eager to note that libertarians like Julian Sanchez and Tim Lee have the right take on this. I note that this issue is specifically addressed in the Constitution, which says that patents and copyrights should be granted “for limited times”—i.e., not as a transcendent moral right—in order “to promote the progress of science and the useful arts,” again, not as a matter of transcendent moral right.
Justice Stevens’ characterization of reward to the author as “a secondary consideration” of copyright law, post, at 6, n. 4 (internal quotation marks omitted), understates the relationship between such rewards and the “Progress of Science.” As we have explained, “[t]he economic philosophy behind the [Copyright] [C]lause … is the conviction that encouragement of individual effort by personal gain is the best way to advance public welfare through the talents of authors and inventors.” Mazer v. Stein, 347 U.S. 201, 219 (1954). Accordingly, “copyright law celebrates the profit motive, recognizing that the incentive to profit from the exploitation of copyrights will redound to the public benefit by resulting in the proliferation of knowledge…. The profit motive is the engine that ensures the progress of science.” American Geophysical Union v. Texaco Inc., 802 F. Supp. 1, 27 (SDNY 1992), aff’d, 60 F.3d 913 (CA2 1994). Rewarding authors for their creative labor and “promot[ing] … Progress” are thus complementary; as James Madison observed, in copyright “[t]he public good fully coincides … with the claims of individuals.” The Federalist No. 43, p. 272 (C. Rossiter ed. 1961). Justice Breyer’s assertion that “copyright statutes must serve public, not private, ends” post, at 6, similarly misses the mark. The two ends are not mutually exclusive; copyright law serves public ends by providing individuals with an incentive to pursue private ones.