Introduction

The history of logic is, in effect, the history of thought. This is not merely because the object of logic is that of consistent rules of cognition, but also because logic itself often parallels the development and the general course of both mathematics and philosophy. Logic can also be thought of as the basic structure by which all language must conform to semantically make sense. Logic also provides machines with a strict set of rules by which to operate. Thus, one may see that logic extends far beyond mathematics and philosophy into the realm of linguistics and computer science and, even more broadly, into everyday life. In this essay, I shall explore the history of logic, starting from its ancient roots into the medieval and modern eras, and finally, examine contemporary developments.

The Origins of the Term Logos

The origin of the term logic is in the term ‘Logos,’ a Greek term that has a rather ambiguous sense. The origin of ‘Logos’ is found in the Proto Indo-European root ‘leg-’, (Etymonline), which meant ‘to collect’ or ‘to gather’ and evolved to mean, in the Greek tongue, “pick up, gather, choose”, “count”, or “say, speak” (Minar 1939). As one can observe, it is quite a nebulous term. Eventually, the term began to be used to reference Jesus in the New Testament, although “[the word often was utilized in the merely conventional, non-symbolic sense in the Bible. It is also often used in the Bible to reference the revelation of God in the world. It was famously used in the passage John 1:1, saying “In the beginning was the Word, and the Word was with God, and the Word was God.”(King James Bible, 1769/2017, John 1:1). Indeed, the term has an early mathematical origin in classical Greek society, often being used to describe ratios and mathematical relationships (Logos Staff 2023).

Logos in Early Greek Philosophy

In addition to mathematics, the term ‘Logos’ was utilized in philosophy as early as the pre-Socratics, most importantly by Heraclitus of Ephesus. Instead of the conventional sense of ‘Logos’ meaning ‘word’ or ‘account’, Heraclitus took the term as a sort of cosmological principle unifying all things. It offers a sort of operator signifying a metaphysical rationality binding all things together and offering access to a sort of universal order (Graham).

Plato and the Rise of Dialectic

Now, in post-Socratic philosophy, we begin to see the formulation of what would truly become ‘logic’. Beginning with Plato, Logos appeared frequently as reasoned discourse. In the Republic, Logos is integral to the dialectical ascent toward the knowledge of the Forms (Plato 2012/380 B.C.E).

Aristotle and the Birth of Formal Logic

We turn now to Plato’s student, Aristotle. Aristotle’s first major work was a compilation of logical writings, which came to be known as The Organon or The Instrument, as logic was originally seen as an instrument by which one could conduct philosophy. Aristotle further refined the term ‘logos’ and distinguished rhetorical devices into a triadic framework of Logos, or appeal to reason, Pathos, or appeal to emotion, and Ethos, or appeal to authority. For Aristotle, Logos was the cornerstone of rational argumentation and the engine of demonstrative knowledge (Aristotle, 2010/4th century B.C.E). Aristotle invented formal logic; however, he called it ‘analytics’ (Kneale & Kneale 1962). Aristotle, in his Organon, defines three important terms: the premise, or a statement affirming or denying one thing of another (for example, ‘grass is green’), the term, or a subject or predicate of a premise (for example, ‘green’ or ‘grass’ and a syllogism, or the discourse wherein the premises necessarily lead to a distinct conclusion (for example, A is B, B is C, therefore A is C) (Andres 2003 pp. 90-91). This is the birth of syllogistic logic.