as the ability to draw reliable conclusions that move beyond the confines of immediate experience. It’s also the power to govern your actions, emotions, desires, and expectations in such a way that they will make sense, given all the realities with which you have to do.
Solon, an Athenian statesman, warned that people should “Be led by reason.” At some point, you may have told someone “Please be reasonable” when their actions, attitudes, emotions, expectations, or beliefs are out of line with what you thought the realities of their situation were. When you say such a thing, you typically want the unreasonable person to come into line with whatever the evidence is that would indicate a better course of action, emotion, or thought, or a more rational conclusion than what that person has chosen, or drifted into instead. Reason used well is able to better connect us with reality, and thus better guide us into the future.
Reason is of great importance in life. But it is neither as extensive nor as pure as some philosophers of the past have assumed. What we are able to perceive, how we organize our perceptions, and what we conclude from our experience is often as much a result of nonrational feelings and attitudes as it is of rational rules and constraints. That’s why it can be hard to reason someone out of a false belief they enjoy holding or feel a need to embrace.
THE GREAT THINKERS ON OUR TENDENCIES TO BELIEVE
Great minds have always commented on our tendency to form beliefs even when there is no good evidence to think they are true.
It is natural for the mind to believe, and for the will to love; so that, for want of true objects, they must attach themselves to false.
— Blaise Pascal (1663 – 1662)
Men freely believe that which they desire.
— Julius Caesar (100 – 44 BCE)
Man prefers to believe what he prefers to be true.
— Francis Bacon (1561 – 1626)
We are born believing. A man bears beliefs as a tree bears apples.
— Ralph Waldo Emerson (1803 – 1882)
Every man, wherever he goes, is encompassed by a cloud of comforting convictions, which move with him like flies on a summer day.
— Bertrand Russell (1872 – 1970)
Each man’s belief is right in his own eyes.
— William Cowper (1731 – 1800)
The greatest part of mankind have no other reason for their opinions than that they are in fashion.
— Samuel Johnson (1709 – 1784)
Logic can’t lead us all the way in life. But logic, or the universal laws of reliable thought, can indeed keep us more closely aligned with reality if our perceptions themselves are in tune with the way the world really is. As philosopher Jean de La Bruyère remarked centuries ago: “Logic is the art of making truth prevail.” Logic alone can’t turn a dead fish into a diamond. But it can take us from diamonds to more diamonds. It can display the interconnections of truth.
LOGIC 101: AN INTERLUDE
Simply put, logic is the study of human reasoning. The laws of logic are those patterns of reasoning that will allow you reliably to stick to the truth if you’ve started with the truth. In other words, logic itself is not an ultimate source of substantive truth of any sort at all, but it’s like a mechanism, or a set of universal rules, or procedures, for moving from known truths to previously undetected truths.
The subject matter of logic is arguments. In a logical argument, no one actually needs to be disagreeing with anyone. It can be simply a search for truth.
In logic, an argument is a series of propositions, or statements about reality, one of which is a conclusion drawn from the others, the latter thereby serving in that context as premises or starting points for arriving at the conclusion.
Here’s a little lingo to impress your friends. In deductive logic, a valid argument is an argument of such a form or nature that, if all its premises are true, then you have an absolute 100 percent guarantee that its conclusion is, too. Here is an example of a valid argument, based on a simple, reliable form of deductive reasoning, or inference, called by logicians modus ponens:
(1) If A, then B
(2) A
Therefore
(3) B
Suppose it’s true that (1) If it’s raining, then your car is getting wet (because you parked outside). If it’s also true that (2) It is raining, then the conclusion follows logically from (1) and (2) that (3) Your car is getting wet. Now, that’s not an exciting conclusion, unless the car is a nice convertible and you remember leaving the top down.
A valid argument with all true premises is called a sound argument. Simply put, in arguments, soundness = validity + truth. Only a sound argument completely guarantees the truth of its conclusion. An argument can be unsound in either of two ways. It can have a false premise. Or it can be invalid, involving the sort of faulty reasoning that, even if all its premises were true, its conclusion could still be false.
With inductive logic, the truth of the premises just raises the probability of, or renders more likely, or gives evidential support to, the conclusion, without giving a 100-percent guarantee that it is true. Here is an example of inductive reasoning:
(1) All objects of type A that we have seen have had property B.
(2) There is likely nothing atypical about any A-type objects not yet seen.
Therefore, probably,
(3) The next A that we see will have property B.
Inductive logic is not as ironclad as deductive reasoning, but it is the basis for most science and technology, and has achieved tremendous results.
The standard philosophical analysis of knowledge presents it as nothing more, or less, than properly justified true belief. The concept of justification here is that of rational justification. So philosophers have asked throughout the centuries, “What is required for rational justification?” The question is what might be needed to support a belief if that conviction is to have a chance of qualifying as knowledge. And the question can be put in other ways: What makes a belief rational or reasonable to hold? What indicators of truth does rationality demand?
There are people who seem to think that something like strict logical proof is required for rationality. Their mantra is “Prove it.” An old friend, who was a distinguished professor at Yale, once recounted that he had received an unexpected
