Two kinds of support

An argument, as these books set it out, is a claim made with reasons. Deduction and induction part company in how far the premises guarantee the truth of the conclusion. In a deduction, true premises make the conclusion true as well. In an induction, they only raise the chance that it is true. Inductive conclusions are often put to work later as the premises of a deduction, which is why a false premise — a candidate's falsified academic record is the example given — can bring the trust of a later conclusion down with it.

A good argument, in this account, needs relevance, true premises, enough grounds, and an answer to an expected objection. Fallacies are the mistakes that get in the way of that work, or pull it down. Formal fallacies are wrong in the form of the argument itself. Informal fallacies break the rules of a conversation or the conditions of a good argument. The point of learning the theory, the writer says, is to read a column or an editorial properly.

A reading order, and a fair hearing

The starting point of logical thinking, in The Force of Logic (논리는 나의 힘), is the habit of asking for reasons. First make the premises and the conclusion clear. Then see whether the way the premises support the conclusion is inductive or deductive. Check whether the premises are relevant and whether they are true. Ask, too, whether the support is as weak as a single case. A person who thinks logically is described as someone who holds down a private feeling and looks for a reason many people can accept. A person who does not is described as thinking and acting on impulse. If the premises or the conclusion are still vague, they should be made clear before the discussion goes on. Denying an economic forecast on the basis of someone's school or job is given as an argument that has no relevance. Evidence found online, the writer adds, is more reliable when you check its truth yourself.

The principle of charity belongs with that care. It is not worth pulling a whole argument down for a minor fault. Discussion becomes more productive when the other person is first taken as reasonable. Logic, in this closing note, is a force that brings a person back to the actual world when feeling has taken over, and the books are recommended from high school through university. The habit they teach is modest and repeatable: find the claim, find the reasons, and then ask how tightly they hold.

Sources

1. a reading of two introductory logic books on deduction and induction, the conditions of a good argument, formal and informal fallacies, a practical order for evaluating a text, and the principle of charity.

Last updated: 14 November 2026