There is spark. The car will not start. Therefore, there is no fuel. Reasoning by analogy is reasoning in which we infer a conclusion based on similarity of two situations, as in the following example. The flow in a pipe is proportional to its diameter.
Wires are like pipes.
Therefore, the current in a wire is proportional to diameter. Now try price. Of all types of reasoning, deductive reasoning is the only one that guarantees its conclusions in all cases. It has some very special properties and holds a unique place in the history of logic. In this book, we concentrate entirely on deduction and leave these other forms of reasoning to others.