Introduction

What is philosophical logic? Philosophical logic is philosophy that is logic, and logic that is philosophy. It is where philosophy and logic come together and become one. Philosophical logic is not a special kind of logic, some species distinct from mathematical logic, symbolic logic, formal logic, informal logic, modern logic, ancient logic, or logic with any other familiar modifier. There is only logic. Logic is the theory of consequence relations, of valid inferences. As such, it can be investigated and presented in many ways, although the mathematical methods of modern formal or symbolic logic have proved extraordinarily fruitful.