On the topic of if someone would take a pill to increase their intelligence, Lex is coming from an implication-driven perspective and Richard is trying to talk about the empirical likelihood of whether or not people would actually take it and why. For this reason, I think Lex is being less rational because his perspective would only matter after they took the pill and had lived a while with the increased intelligence. Richard is reasoning 'would' and Lex is reasoning 'should'.