The 15th-century Venetian navigator Alvise Cadamosto describes a curious convention by which the Mauritanian Azanaghi traded salt with the merchants of Mali:

All those who have the salt pile it in rows, each marking his own. Having made these piles, the whole caravan retires half a day’s journey. Then there comes another race of blacks who do not wish to be seen or to speak. They arrive in large boats, from which it appears that they come from islands, and disembark. Seeing the salt, they place a large quantity of gold opposite each pile, and then turn back, leaving salt and gold. When they have gone, the Negroes who own the salt return: if they are satisfied with the quantity of gold, they leave the salt and retire with the gold. Then the blacks of the gold return, and remove those piles which are without gold. By the other piles of salt they place more gold, if it pleases them, or else they leave the salt. In this way, by long and ancient custom, they carry on their trade without seeing or speaking to each other.

In this way different cultures can trade safely without speaking the same language. It’s called the “silent trade”; Herodotus describes a similar practice between Carthage and West Africa, and it’s been reported also in Siberia, Lapland, Timor, Sumatra, India, Sri Lanka, and New Guinea.

Why didn’t the Malians simply take the salt? Presumably because trade was more valuable to them in the long run. I wonder how such a custom gets started in the first place, though.

In the year 4299, five cave explorers are trapped by a landslide. To stay alive they decide to engage in cannibalism, choosing the victim by throwing dice. When the four survivors are rescued, they’re convicted of murder and face a mandatory sentence of death. After a public outcry, the “Supreme Court of Newgarth” takes up the case. Its five judges subscribe to five different legal philosophies, with the result that two vote to affirm the convictions, two vote to overturn them, and one recuses himself. As this is a tie, the original conviction is upheld and the four explorers face death.

Harvard philosopher Lon L. Fuller presented this story in 1949 to contrast various legal philosophies prevailing in the 20th century, primarily natural law and legal positivism.

But in the ensuing years, dozens of further hypothetical judgments have been offered by writers from perspectives ranging from historical contextualism to process theory. Frank Easterbrook wrote in 1999 that Fuller’s essay combines “a timely consideration of contemporaneous debates with a timeless quality that continues to entice students and scholars to think and write about [it] some half a century later — and will doubtless engage our successors well into the next millennium.”

Fuller had written, “The case was constructed for the sole purpose of bringing into a common focus certain divergent philosophies of law and government. These philosophies presented men with live questions of choice in the days of Plato and Aristotle. Perhaps they will continue to do so when our era has had its say about them. If there is any element of prediction in the case, it does not go beyond a suggestion that the questions involved are among the permanent problems of the human race.”

(Lon L. Fuller, “The Case of the Speluncean Explorers,” Harvard Law Review 62:4 [February 1949], 616–645.)

How can a just law have a claim on our obedience? Murder is wrong, regardless of what the law says about it; we expect people to refrain from murder because it’s wrong, not because it’s prohibited or punished. I’d be offended if someone suggested that it’s only respect for the law that’s restraining me from committing murder. But this suggests that we don’t have an obligation to obey laws that prohibit murder — a morally conscientious person should never find himself obliged to submit to them.

“The more just and valuable the law is … the more reason one has to conform to it, and the less to obey it,” writes legal philosopher Joseph Raz. “Since it is just, those considerations which establish its justice should be one’s reasons for conforming with it, i.e., for acting as it requires. But in acting for these reasons one would not be obeying the law, one would not be conforming because that is what the law requires.”

(Note, though, that Raz says the paradox is only apparent — see his full paper here.)

(Scott Hershovitz, “The Authority of Law,” in Andrei Marmor, ed., The Routledge Companion to Philosophy of Law, 2012.)