Problem:  Cato promises Isabella $40,000 if she graduates from State College. Isabella enrolls in State, attends full-time for four years,...

Problem:  Cato promises Isabella $40,000 if she graduates from State College. Isabella enrolls in State, attends full-time for four years, and graduates. When she asks Cato for $40,000, he says, “I don’t re­member promising you $40,000. But if there was a promise, it’s not en­forceable, because we didn’t bargain for it. And even if there was a prom­ise that would otherwise be enforceable, I revoke it now.” Can Isabella en­force Cato’s “prom­ise”? Why or why not?