Session #2 of the REINFORCE Critical & Scientific Thinking course, 'The Four Rs', is given by Nobel Prize laureate Saul Perlmutter, Professor at the University of California, Berkeley, Lawrence Berkeley National Laboratory. During this session, Prof. Perlmutter continues with an explanation of the Sense and Sensibility and Science course, developed at UC Berkeley, focussing on the so-called 'Can-Do' aspects of science, such as Scientific Optimism, as well as the ideas of Confirmation Bias and Blind Analysis; and Group Thinking. The session poses the question of whether the concept of the Three Rs should evolve into the Four Rs: Reading, Writing, Arithmetic and Scientific Reasoning.