ABSTRACT
This chapter discusses the views of two philosophers who have considered the evidence from split-brain patients. It describes the features of the two systems claimed by supporters of the dual system theory. The chapter shows that the R-mind lacks true language, that it processes sensory inputs more quickly than the L-mind, and that it achieves lower scores on IQ tests than the L-mind. Mental processes in the early hominid brain, as in the brain of their primate predecessors, were shared between the two hemispheres. The development of the L-mind did not replace all the existing processes in the left hemisphere: it added new processes and modified others. The left hemisphere therefore includes both System 1 and System 2 processes, whereas the right hemisphere includes only System 1 processes. The chapter explains why the interpreter module in the left hemisphere must make assumptions about actions initiated by the R-mind, and may be forced to confabulate.
