Introduction

According to the theory of evolution, human beings have evolved from the lower species over many millennia. The chief asset that made humans “superior” to their ancestors was the ability to reason. How well this ability has been used for scientific and technological development is common knowledge. But no systematic study of logical reasoning seems to have been done for a long time. The first such study that has been found is by Greek philosopher Aristotle (384-322 BC). In a modified form, this type of logic seems to have been taught through the Middle Ages.

Then came a major development in the study of logic, its formalisation in terms of mathematics.It was mainly Leibniz (1646-1716) and George Boole (1815-1864) who seriously studied and development this theory, called symbolic logic. It is the basics of this theory that we aim to introduce you to in this unit and the next one. 

In the introduction to the block you have read about what symbolic logic is. Using it we can formalise our arguments and logical reasoning in a manner that can easily show if the reasoning is valid, or is a fallacy. How we symbolise the reasoning is what is presented in this unit.

Objectives

After reading this unit, you should be able to:

• distinguish between propositions and non-propositions;
• construct the truth table of any compound proposition;
• identify and use logically equivalent statements;
• identify and use logical quantifiers.