Being Logical is a practical book that aims to help readers think and reason well.

It is divided into five parts. Part One (Preparing the Mind for Logic) talks about the preparations we need to make in order to think and reason well. These preparations refer to attitudes and ways of thinking that we need to adopt and the concepts that we need to remember in order to ready our minds for good thinking and reasoning.

These are the concepts we need to remember:

1. Facts (that is, objective facts of the external world, like things and events),
2. Ideas (which are the "representations" of the objective facts),
3. Mind (ours and those of others),
4. Words (which are the linguistic expression of ideas and the building blocks of language),
5. Statements/ propositions (which are the building blocks of logic),
5. Knowledge (which consists of objective facts, ideas and words).

Part Two (The Basic Principles of Logic) talks about the laws of logic. They govern logical thinking. They are the foundation upon which organized and good thinking is based. We ignore these principles at our own peril. If our beliefs (or ideas) about the world violate any of these principles, they are necessarily false.

In particular, these four first principles in logic are important:

1. The principle of identity.
2. The principle of the excluded middle.
3. The principle of sufficient reason.
4. The principle of contradiction or non-contradiction.

Two important things to remember when it comes to first principles/ laws:

1. They are self-evident, and
2. They cannot be proven.

Part Three (Argument: The Language of Logic) talks about arguments.

What is an argument? An argument is basically the linguistic expression of logical thinking. It is a claim that is justified by reasons and/or evidences.

It has two elements:
1. Premises
2. And a conclusion

So, basically, an argument is composed of statements or propositions. It has a conclusion and it is supported by premises.

There are basically two kinds of arguments:

1. Deductive arguments, and
2. Inductive arguments

Deductive arguments, if successful, yield necessarily true conclusions.

Inductive arguments, if successful, only yield conclusions that are probably true.

A good argument has to fulfill these requirements:
1. Its premises (or contents) are true and relevant, and
2. Its form (or structure) is valid
3. In the case of inductive arguments, the premises must also be strong enough to support the conclusion

Arguments have two purposes:

1. To produce true conclusions (that's why it's a "science")
2. To persuade people (that's why it's an "art")

Part Four (The Sources of Illogical Thinking) talks about the attitudes that we must avoid because they can be sources of irrational thinking. These attitudes and mindsets negatively affect the way we think and the way we reason.

Part Five (The Principal Forms of Illogical Thinking) talks about logical fallacies. They are the different ways in which an argument can go wrong.

There are basically two categories of logical fallacies, the formal and the informal logical fallacy.

Formal logical fallacies are mistakes that involve the "form" or "structure" of the argument. For example, in a conditional argument, the only valid inferential moves are affirming the antecedent (modus ponens) and denying the consequent (modus tollens). Therefore, if you instead make the inferential move of denying the antecedent and/or affirming the consequent, you are committing a formal logical fallacy.

Informal logical fallacies are mistakes that a person commits when, instead of addressing his opponent's argument, he divert's his or the audience's attention by, for example, appealing to emotions (ad hominem, red herring, etc.), or by simply distorting or caricaturing his opponent's argument in order to easily demolish it (straw man fallacy). There are many more examples of the informal logical fallacy.

The author proposes that in order to think and reason well and effectively, the reader must master all the concepts and principles contained in this book, and moreover, he or she must practice them constantly.

I really love this book because it explains in clear and concise language the basics of logic. It is relatively easy to understand. Now, I can move on to more advanced logic texts.