Being Logical: A Guide to Good Thinking

by D.Q. McInerny

Be Attentive

Attention demands an active, energetic response to every situation, to the persons, places, and things that make up the situation.

Don’t just look, see. Don’t just hear, listen. Train yourself to focus on details.

The little things are not to be ignored, for it is just the little things that le...

Get the Facts Straight

Facts can also be thought of as objective or subjective. Both things and events are objective facts. They exist in the public domain and are in principle accessible to all. A subjective fact is one that is limited to the subject experiencing it.

If a given fact is an actually existing thing to which we have access, then the surest way to establish its factualness is to put ourselves in its presence. We then have direct evidence of it. If we cannot establish factualness by direct evidence, we must rigorously test the authenticity and reliability of whatever indirect evidence we rely upon so that, on the basis of that evidence, we can confidently establish the factualness of the thing.

Ideas and the Objects of Ideas

An idea is the subjective evocation of an objective fact. Clear ideas, then, are ideas that faithfully reflect the objective order from which they derive. Unclear ideas, conversely, are those that give us a distorted representation of the objective world.

Our ideas are the means, not the ends, of our knowledge. They link us to the world. If they are clear ideas, the links are strong. The most efficient way to clarify our ideas is to look through them to the objects they represent.

Be Mindful of the Origins of Ideas

Our ideas owe their existence, ultimately, to things outside and independent of the mind, to which they refer: objective facts.

Match Ideas to Facts

There are three basic components to human knowledge: first, an objective fact (e.g., a cat); second, the idea of a cat; third, the word we apply to the idea, allowing us to communicate it to others (e.g., in English, “cat”).

Bad ideas do not just happen. We are responsible for them. They result from carelessness on our part, when we cease to pay sufficient attention to the relational quality of ideas, or, worse, are a product of the willful rejection of objective facts.

Match Words to Ideas

As we have seen, first comes the thing, then the idea, then the word. If our ideas are sound to the extent that they faithfully represent the thing, they will be clearly communicable only if we clothe them in words that accurately signify them.

Effective Communication

Matching words to ideas is the first and most basic step in communication. The next step is putting ideas together to form coherent statements.

Avoid Vague and Ambiguous Language

Avoid Evasive Language You should always be so straightforward in your language that it would be impossible for any reasonably attentive audience to miss your meaning.

10. Truth

The whole purpose of reasoning, of logic, is to arrive at the truth of things.

two, ontological truth is the more basic. By ontological truth we refer to the truth of being or existence. Something is said to be ontologically true, then, if it actually exists; it has real being. The lamp sitting on my desk is ontologically true because it is really there. It is not an illusion. The opposite of ontological truth is nonexistence. Logical truth, as you might suspect, is the form of truth we are most directly concerned with as logicians. Logical truth is simply the truth of statements.

More broadly, we could say that it is truth as it manifests itself in our thinking and language.

First Principles

A science is any organized body of knowledge that is possessed of first principles.

THE PRINCIPLE OF IDENTITY

Stated: A thing is what it is.

Explanation: The whole of existing reality is not a homogenous mass. It is a composition of individuals, and the individuals are distinguishable from one another. If a thing is what it is, obviously it is not something other than what it is. An apple is an apple. It is not an orange, a banana, or a pear.

THE PRINCIPLE OF THE EXCLUDED MIDDLE Stated: Between being and nonbeing th...

Explanation: Something either exists or it does not exist; there is no halfway point between the two. The lamp sitting on my desk is either really there o...

THE PRINCIPLE OF SUFFICIENT REASON

Stated: There is a sufficient reason for everything. Explanation: The principle could also be called “the principle of causality.” It states that everything that actually exists in the physical universe has an explanation for its existence.

THE PRINCIPLE OF CONTRADICTION Stated: It is impossible for something both to be and not be at the same time and in the same respect. Explanation: This principle could be regarded as a fuller expression of the principle of identity, for if X is X (principle of identity) it cannot at one and the same time be non-X (principle of contradiction). The phrase “in the same respect” in the statement refers to the mode of existence in question.

If the primary purpose of logic is to attain the truth, then it is evident that nothing could be more important than avoiding the opposite of truth.

Real Gray Areas, Manufactured Gray Areas

Gray can exist as gray only because there are the distinct alternatives of black and white. That you might find yourself at times in a situation in which you see no clear alternatives does not mean, objectively considered, that there are no clear alternatives. It simply means that you do not see them. Don’t project your subjective state of uncertainty upon the world at large and claim objective status for it.

There’s an Explanation for Everything, Eventually

Don’t Stop Short in the Search for Causes

Distinguish Among Causes

In efficient causality a distinction can be made between the “principal cause” and the “instrumental cause.” We say that a sculptor is the principal cause of a marble statue, because he is the ultimate explanation for its existence. But he is not the only explanation, for he needed tools to make the statue. In an important sense those tools caused the statue, albeit in a subordinate way—as instruments in the hands of the sculptor. The instruments are the means through which a principal efficient cause brings about a certain effect.

Define Your Terms

The most effective way to avoid vagueness or ambiguity in logical discourse is to define one’s terms. We speak of defining terms, but actually what we are defining is the objects to which terms (words) refer.

The Categorical Statement

The purpose of the reasoning process, logic’s principal concern, is demonstration. I am not reasoning with you if I simply say that such-and-such is true and expect you to accept it as true only on my say-so. I must show you that such-and-such is true, and I do that by making an argument. An argument will only be as good as the statements of which it is composed, and those statements, in turn, will only be as good as the terms of which they are composed.

The most effective argument is one whose conclusion is a categorical statement. A categorical statement tells us that something definitely is the case.

Generalizing

A general statement is one whose subject is very large in scope. Such a statement is not necessarily inaccurate. “Horses are vertebrates” and “Houses are domestic dwellings” are general statements, and there is no reason to dispute the claims they are making.

There are two types of general statements, the universal and the particular. A “universal affirmative statement” is an “every” or “all” statement (“All whales are mammals”). It affirms something about an entire class. A “universal negative statement” is a “no” statement (“No fish have feet”). It denies something of an entire class. A “particular statement,” affirmative or negative, does not refer to each and every member of the class specified by its subject. It is usually marked by the qualifier “some” (“Some mammals are arboreal”; “Some potatoes are not new”).