To the logical realist, mathematical truths reside in the mind, independent of the brain, meaning they are discovered. Conversely, the logical nominalist argues that mathematics is a construct of the human brain. As an invention, mathematics only stipulates the use of certain symbols, much like how the rules of chess govern how the pieces can move. This book discusses realism vs. nominalism within systems of logic. In this insightful examination, The Heart of Man brilliantly exposes the current crisis in logic.