The basis of this work is to lay the groundwork for relational thinking in mathematics by giving a general mathematical definition of relational thinking in mathematics that builds on the theory of relational thinking in arithmetic and then extends that theory to include all other mathematics subjects, especially algebra and geometry. The necessity to include all other mathematics subjects in relational thinking is predicated on the need for students at all levels to be able to think relationally. In an effort to further establish relational thinking in mathematics, this work attempts to merge mathematics and philosophy by examining Plato's Meno and Wittgenstein's Philosophical Investigations to show the importance of deductive reasoning, l...