The Basics of Reasoning

At the heart of all critical thinking lies a simple question: how do we know what we know? Whether we’re making a personal decision, crafting an argument, or evaluating someone else’s claim, we rely on reasoning to draw conclusions. But not all reasoning works the same way. In fact, most of the arguments we encounter fall into one of two major categories: deductive reasoning and inductive reasoning. These are not just academic labels—they are the mental tools we use to navigate daily life, whether we’re aware of them or not.

Deductive reasoning is about certainty. It starts with general principles and uses them to reach specific, logically guaranteed conclusions. If the premises are true and the structure is valid, then the conclusion must also be true (Moore & Parker, 2017). In contrast, inductive reasoning is about probability. It moves from specific observations to broader generalizations. Inductive arguments are not guaranteed to be true, but they can be highly persuasive and practically useful—especially in science, media, and everyday decision-making.

Understanding the differences between these two forms of reasoning is essential for evaluating arguments. But it’s also the key to becoming more precise in your own thinking. In this chapter, we’ll break down both types of reasoning, explore their structures, examine common pitfalls, and show how they shape the arguments that influence our world.

Understanding Deductive Reasoning