"By being more true to the novel, Bastiat does not need to rely on the arrival of Friday to illustrate the importance of exchange. Instead, he points out that Crusoe brings the benefits of exchange with him to the island in the form of the salvaged goods. Later writers wished to more clearly separate the isolated Crusoe from the benefits of exchange that they present as made possible only by Friday’s arrival. Bastiat argues that it is nearly impossible to even conceive of an individual surviving without implicitly assuming that exchange (even if only exchange that has taken place in the past, before Crusoe’s shipwreck) with other humans already exists.
Bastiat drives this point home even more firmly by pointing out that Defoe has Crusoe arrive on the island with a “social treasure worth a thousand times more” than the remains of the wreck. Bastiat here refers to Crusoe’s “ideas, his memories, his experience, and especially his language,” all of which take for granted society and exchange. The Robinson Crusoe of Defoe’s novel was not completely isolated from society and exchange in the way economists later assumed him to be in order to illustrate the economics of isolation. So when later writers, including modern textbook writers, use Crusoe to explain how even an isolated human has to allocate his limited resources among various possible uses, they must either implicitly assume the pre-existence of exchange by virtue of their description of Crusoe, or they must do violence to the novel by making Crusoe even less human and more isolated than Defoe thought was plausible. They must deny those precious advantages of culture and experience that Bastiat praises."