Why is it important to have good reasons for one’s beliefs?

Without good reasons, "humans have no hope of understanding all that we fondly call weird — or anything else for that matter." (2)

Reductio argument:

To prove: not all reasons are equally good (worthy of belief).

Suppose: (P1) all reasons are equally worthy of belief.

(P2) If all reasons were equally good, then any reason offered in support of any claim would be equally convincing. E.g., you say a house fire is caused by faulty electrical wiring, and I say the same fire is caused by the fact that a butterfly landed on the nose of the Empress of China in the 14^th century. Both these explanations must be equally convincing.

(P3) The two explanations are not equally convincing.

(C1) P2 and P3 are contradictory.

(C2) Therefore, not all reasons are equally worthy of belief.

Students have told me they don’t care about good reasons because

• They don’t want to understand the world (because understanding the world leads to controlling nature and wrecking the environment and we’d all be better off leaving nature alone … i.e., they start giving what they believe are good reasons for their view);
• They think that all this emphasis on reason is a patriarchal, Euro-centric oppressive mechanism designed to keep down the powerless (because reasoning ability has always been associated with males, and feminine intuition has been consistently devalued and so have so-called "primitive" peoples, and it’s about time we were serious about liberation … i.e., they start giving what they believe are good reasons for their view);
• They think science will change its mind about everything sooner or later (because they’ve seen scientists change their minds about oat bran and eggs and cholesterol and smoking, so obviously science doesn’t provide any lasting answers … i.e., they give an argument).

These students obviously care deeply about good reasoning even as they reject reason. They implicitly presuppose the view they claim to reject. This is weird!

In a way, the question "Why is it important to have good reasons for our beliefs?" is a non-question for humans. Aristotle recognized this. Why are some reasons better reasons? The ultimate answer here is: you can’t seriously ask this question. If you believe you’re seriously asking this question, think again. By asking, you’re acknowledging that some reasons might convince you that some reasons are better reasons. Your question itself takes for granted that some proffered answers would be better than others. I.e., you don’t really need to be convinced that some reasons are better than others. Implicitly, you’re already asking for good reasons; i.e., you’re acknowledging exactly what you’re challenging the reasoner to prove. You’re caught in a profound contradiction: you maintain it’s both true (and indubitable) and, at the same time, up for grabs (dubitable) that some reasons are better than others.

Another reductio:

To prove: not all reasons are equally good.

Suppose: (P1) all reasons are equally good.

(C1) Every claim is equally well-supported; no claim has better support than any other.

(P2) There is a world.

(P3) Some things in the world are a certain way independently of whether anyone believes them. For example, there are laws of nature that make events very predictable. Whether or not I believe it, I will most probably burn my hand if I leave it in the fire.

(C2) Not all claims are equally well-supported: for example, the claim "If I put my hand in the fire for five minutes, it will not burn" is not as well-supported as the claim "If I put my hand in the fire for five minutes, it will burn." (From P2 and P3)

(C3) C1 and C2 are contradictory.

(C4) P1 must be false.

In fact "true" usually means "corresponding to the way things are." Rejecting truth means rejecting the idea that things are a certain way.

You might counter: exactly! Things aren’t any particular way. What is real for one person isn’t necessarily real for another. We each have our own reality.

What does that mean?

Of course, we each have unique experiences and life histories and preferences, etc. You can say metaphorically that we each live in a different "world". But that doesn’t means that we literally live in different worlds. There is a literal world external to our minds, and in many important ways, it’s the same world for all of us.

Pointing out that there is one world is not to deny or disrespect our "private" "worlds".

Or would it okay to maintain some beliefs that we know are unreasonable if those beliefs make us feel good and we don’t force them on others?

It depends.

What do you mean by "okay"? If you mean "legal", then yes, it’s okay (not illegal) to believe unreasonable things. But people usually mean more. They want to say it’s okay in the sense of "reasonable". So let’s rephrase: might it be reasonable (as well as legal) in some contexts to adopt unreasonable beliefs? People sometimes say "Anything is possible," implying that we can’t immediately dismiss any claim.

What do we mean by "possible"?

Recall that logic is a formal discipline. That is, the rules of logic are like the rules of mathematics: they describe what is so necessarily, no matter what is actually the case. For example, "2 plus 2 equals 4" is true whether or not you or I exist. It was true even when there were no people, and will remain true even after everything we know has gone out of being. That is, the claim "2 plus 2 equals 4" is necessarily true, or, what amounts to the same thing for most philosophers, the state of affairs expressed by the claim "2 plus 2 equals 4" exists necessarily.

Likewise, some statements are necessarily false. The statement "2 plus 2 equals 5" cannot be true because it is self-contradictory. In other words, the state of affairs expressed by the statement "2 plus 2 equals 5" cannot exist. That 2 plus 2 should equal 5 is logically impossible. Thus, roughly speaking, something is logically possible if it implies no logical contradiction.

Sometimes philosophers talk about logically impossible states as "inconceivable" or "unimaginable." Defining "logically impossible" as "inconceivable" is problematic, of course, since what is inconceivable at one time may become conceivable later. But we'll worry about that later. If you want to think of "logically impossible" as "inconceivable," that's close enough for our immediate purpose, which is to get a sense of the difference between logical impossiblility and physical impossibility.

Violations of the law of the excluded middle always result in logical impossibility. The law of the excluded middle says a statement cannot be both true and false in the same sense at the same time. So in court,if one witness says "The defendant was at the crime scene at 8:00 PM on the night of the crime" and another equally reliable witness says "The defendant was not at the crime scene at 8:00 PM on the night of the crime," the testimony of the second witness cancels out the testimony of the first. If the first witness's claim is true, the second's is false and vice versa. It is logically impossible that both claims be true; that is, it is logically impossible that the defendant both was and was not at the crime scene at a specific time. We can derive NO knowledge from logically contradictory claims.

Something is physically impossible if it is conceivable but impossible given our current state of understanding of the laws of nature.

Thus, anything logically impossible is physically impossible. For example, a round square is both logically and physically impossible. It's logically impossible that 2 plus 2 equals 5, and it's also physically impossible for 2 apples plus 2 apples to yield 5 apples.

On the other hand, NOT everything physically impossible is logically impossible. For example, it is logically possible (conceivable) but physically impossible, given our current understanding of the laws of nature, for a cow to jump over the moon.

These impossibility relationships are illustrated in the following diagram:

Anything physically possible is logically possible. For example, it is both logically and physically possible to be a human, or a male human, or a brown-eyed human.

These possibility relationships are illustrated in the following diagram:

Note the two diagrams have the same content.

So, back to the question: might it be reasonable (as well as legal) in some contexts to adopt unreasonable beliefs? Settling the question of logical vs physical impossibility helps answer this question. It is ALWAYS unreasonable to believe something logically impossible; it is USUALLY unreasonable to believe something physically impossible; it is USUALLY REASONABLE to suspend judgment, other things being equal, if the question of physical possibility is open.

Does the belief relate to a matter that can be settled purely on logical grounds? For example, suppose you want to believe that your current bank account balance is $1,000,000 and that your current bank account balance (in the same bank account) is not $1,000,000. It is logically impossible that the account balance could both be and not be $1,000,000 at the same time. It either is $1,000,000 or it’s not. This case illustrates a fundamental law of logic: the law of non-contradiction. It’s never reasonable to believe a contradiction. Contradictions are both logically and physically impossible.

Does the belief relate to a matter that can be settled on empirical (scientific) grounds? Suppose, for example, you want to believe that copper is not conductive, when you know that it’s generally believed that copper is conductive, and you understand the physics. You say, nevertheless, that copper is not conductive and that if you plug a copper wire into a socket, you won’t get a shock. This belief is unreasonable. If your belief relates to a matter that has been settled on empirical grounds, you are unreasonable not to accept the well-established explanation, and it’s not okay to maintain that belief if "okay" means "reasonable." You are insisting on believing something that is physically impossible (though not logically impossible). Hence the rule: Just because something is logically possible doesn’t mean it’s real or reasonable to believe in.

Does the belief relate to an empirical matter that is currently not settled? Suppose you want to believe that aliens have visited earth or that humans will travel to Mars in your lifetime or that workers will someday overthrow capitalism. Suppose these beliefs give you great psychological comfort, and you know that alien visitation and manned flights to Mars and revolution of the workers are all physically and logically possible. Here we should be careful. We have to consider each case separately.

Does the belief relate to a matter that could never be decided on empirical grounds alone? E.g., that there’s a just God who will reward the good and punish the evil; that life is worth living; that I should (or should not) have children. How do you know these answers? You can line up the arguments on both sides and you’d see that there are equally reasonable (factual and logical) arguments on both sides, so reason can’t decide these questions. These are matters about which the empirical evidence is inconclusive, and, in the case of religion, can’t be conclusive; yet you must choose an answer (your life is hurtling on) and the consequences of not choosing are the same as the consequences of choosing "no". Maybe here we have good reasons, then, to choose our beliefs on the basis of feelings or emotions. But only here. For more on this, see William James’ article "The Will to Believe”.

To avoid appeal to ignorance, remember these rules (p 19):

There are laws of nature. Science is a continuing investigation of the laws of nature. Science is done over the long term. It is a historical enterprise. Later science builds on earlier science. Later science often revises earlier science. A large-scale revision of science — such as the transition from the geocentric to the heliocentric view, or Newton’s laws (which enabled a single set of principles to account for all known phenomena of physics), or the transition from Newtonian to Einsteinian physics — is called a scientific paradigm shift.

Scientific discourse at any particular time takes place within a particular scientific paradigm, or frame of reference. Scientific theories embody that frame of reference. A scientific theory is simply science’s best approximation so far of the particular law of nature being investigated. Scientific experiments at any particular time presuppose particular paradigms.

Paradigm shifts don’t bother scientists; on the contrary, paradigm shifts make scientific progress possible.

A weird phenomenon (also known as an anomaly) simply cannot be understood within the particular scientific paradigm of the age in which the phenomenon occurs. So-called "miracles" are weird in this way. As the philosopher and saint Augustine put it in the fourth century, "A miracle is not contrary to nature but contrary to our knowledge of nature." (SV p. 20-21) Miracles and weird phenomena are often said to be "physically impossible," but this is an inaccurate way of putting it. There is no contradiction between the "miracle" and the laws of nature. If a physical event takes place, it’s obviously not physically impossible. The contradiction is between the event and our current understanding of nature, embodied in our current theories and paradigms.

Schick and Vaughn give two examples of weird phenomena — ESP and precognition — that might be explainable in terms of scientific theories that are currently controversial (tachyons, Minkowski’s interpretation of relativity, spooky action at a distance), but which might become widely accepted as science advances. Or not. It depends on the evidence. Note that so far, there is no agreement among scientists that any cases of ESP and precognition really exist to begin with, let alone whether they can be explained.