Amazon’s algorithm for telling you about books they think you might find interesting (given your past purchases) can deliver some amusing results. “Greetings,” they say today, “we’ve noticed that customers who have purchased Classical Recursion Theory: The Theory of Functions and Sets of Natural Numbers by P. Odifreddi have also purchased If You Were a Set by Evelyn M Aboff …”.

But maybe, on second thoughts, I should take a look at this book for small kids: those misconceptions about sets that the average first year philosophy student seems to have must come from somewhere!