Which of her eager suitors will make the right guess in the gamble – and win the beautiful Portia and her fortune? Mathematician Alex Bellos gives us a new twist to a story familiar from Shakespeare’s The Merchant of Venice: a lovely and virtuous heiress is compelled by her late father’s will to marry the man who chooses, out of three caskets, the one which contains her portrait. In a Theory of Knowledge class, love, luck, literature, and logic combine in a quick class activity solving a problem – and thereby clarifying for students the process of deduction and justification through reason and language as ways of knowing. And it’s fun.
The puzzle can be found in Alex Bellos’ Monday puzzle blog – both the puzzle itself and the solution, with explanations: “Did you solve it? The mystery of Portia’s caskets” It’s easy enough to be obvious, once you’ve thought it through, but hard enough to demand that students have to give it their attention to work it out. If at least one of the three statements is true, and at least one of the three is false, then in which of the caskets is Portia’s portrait to be found?
When students have given a few minutes to the puzzle, there should be several at least who have the solution and are ready to explain to any classmates who are stalled. The question then, in TOK, is “How do you know?” and “What ways of knowing did you use to reach and justify your conclusion?” Puzzles like this one are a quick-and-easy way to illustrate the power of reason to draw out the logical implications of prior information, in order to create new knowledge.
Note that it’s possible to sign up for notification on Mondays as Bellos publishes his puzzle, and to get a constant supply of ideas for TOK.
What I like about this particular puzzle is its storyline, with the winning logician being so richly rewarded. If you’re familiar with The Merchant of Venice, you could suspect that I’m also taken with the love story behind the gamble of the caskets – with its happy ending – and even suspect that the not-so-passive-prize Portia might be one of my favourite literary heroines. That would be mere speculation, not logic. But you’d be right!
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Alex Bellos, “Did you solve it? The mystery of Portia’s caskets”, The Guardian. February 13, 2017. https://www.theguardian.com/science/2017/feb/13/did-you-solve-it-the-mystery-of-portias-caskets