Critical Thinking - a Simple and Concise Look

 I have written a few articles about critical thinking and read a few books on the topic and read numerous articles and watched videos.

I have found that bits and pieces from many subjects are  important and necessary parts of critical thinking. Despite wanting to be brief I ended up including eight different topics in my series of articles on Cornerstones of Critical Thinking because the ideas are so crucial to the subject.

I have described several videos by Richard Paul in detail because the information he goes over is so vital to good critical thinking.

I had resigned myself to the fate of having to dive into many related subjects to begin to tackle critical thinking. It just involves so much.

I was delighted to discover one book that puts forth a lot of the most important and essential information on critical thinking forward in a very short amount of words and in a very thorough but understandable and consistent model.

I enjoyed the book and the presentation of its ideas and model so much that I decided to write this series of posts to describe the work to encourage others to read the book,  to consider the ideas presented and to explore the subject of critical thinking as a serious study. I think it's well worth the effort.

The book I am describing is How to Think about Weird Things: Critical Thinking for a New Age by Theodore Shick, Jr. and Lewis Vaughn. (Fifth Edition)

The book was recommended by David Kyle Johnson as a guest on The Sensibly Speaking podcast with Chris Shelton, by the way. 

I have to include some of the ideas used to lay groundwork before getting to the model itself but compared to other subjects this is quite brief and straightforward.

I want to start with a central question in critical thinking - why? Why do we believe one idea and not another? 

I have explored this idea in great depth in other posts and series including The Knowledge Illusion and Cornerstones of Critical Thinking.

The Knowledge Illusion full series 1 - 16

Cornerstones of Critical Thinking 1 - 8 Introducti...

The authors described it:

"Without good whys, humans have no hope of understanding all that we fondly call weird - or anything else, for that matter. Without good whys, our beliefs are simply arbitrary, with no more claim to knowledge than the random choice of a playing card. Without good whys to guide us, our beliefs lose their value in a world where beliefs are already a dime a dozen." (Page 2)

"The big question then is why? Why do you believe or disbelieve? Belief alone - without good whys - can't help us get one inch closer to the truth. A hasty rejection or acceptance of a claim can't help us tell the difference between what's actually likely to true (or false) and what we merely want to be true (or false). Beliefs that do not stand on our best reasons and evidence simply dangle in thin air, signifying nothing except our transient feelings or personal preferences." (Page 3)

"Aliens, spirits, miracle cures, mind over matter, life after death: wonders all. The world would be a more wonderful place, if these things existed. We wouldn't be alone in the universe, we would have more control over our own lives, and we would be immortal. Our desire to live in such a world undoubtedly plays a role in the widespread belief in these things. But the fact that we would like something to be true is no good reason to believe that it is. To get to the truth of the matter we must go beyond wishful thinking to critical thinking. We must learn to set aside our prejudices and preconceptions and examine the evidence fairly and impartially. Only then can we distinguish reality from fantasy." (Page 12)

"If we can't tell the difference between reasonable and unreasonable claims, we become susceptible to the claims of charlatans, scoundrels, and mountebanks." (Page 13)

(Mountebank - Entry 1 of 2) 1 : a person who sells quack medicines from a platform. 2 : a boastful unscrupulous pretender : charlatan.)

(Merriam-Webster)

"The historian Thomas Kuhn, in his seminal work The Structure of Scientific Revolutions, has shown that science advances only by recognizing and dealing with anomalies (phenomena that don't seem to obey known laws). According to Kuhn, all scientific investigation takes place within a paradigm, or theoretical framework, that determines what questions are worth asking and what methods should be used to answer them. From time to time, however certain phenomena are discovered that don't fit into the established paradigm, that is they can't be explained by the current theory. At first, as in the case of meteorites, the scientific community is forced to abandon the old paradigm and adopt a new one. In such a case, the scientific community is said to have undergone a paradigm shift." (Page 15 -16)

"LOGICAL POSSIBILITY VERSUS PHYSICAL POSSIBILITY

Although it's fashionable to claim that anything is possible, such a claim is mistaken, for there are some things that can't possibly be false, and others that can't possibly be true. The former - such as "2 + 2 = 4," "All bachelors are unmarried," and "Red is a color" are called necessary truths, while the latter - such as "2 + 2 = 5," "All bachelors are married," and "Red is not a color" are called necessary falsehoods. The Greek philosopher Aristotle (Plato's pupil) was the first to systematize our knowledge of necessary truths. The most fundamental of them the ones upon which all other truths rest - are often called the laws of thought. They are:

The law of noncontradiction: Nothing can both have a property and lack it at the same time.

The law of identity: Everything is identical to itself.

The law of the excluded middle: For any particular property, everything either has it or lacks it.

These principles are called the laws of thought because without them thought - as well as communication would be impossible. In order to think or communicate, our thoughts and sentences must have a specific content; they must be about one thing rather than another. If the law of noncontradiction didn't hold, there would be no way to distinguish one thought or sentence from another. Whatever was true of one would be true of the other. Every claim would be equally true (and false). Thus, those who deny the law of noncontradiction can't claim that their position is superior to that of those who accept that law.

One of the most effective techniques of refuting  a position is known as reductio ad absurdum: reduction to absurdity. If you can show that a position has absurd consequences, you've provided a powerful reason for rejecting it. The consequences of denying the law of noncontradiction are about as absurd as they get. Any position that makes thought and communication theoretically impossible is, to say the least, suspect. Aristotle, in Book IV of the Metaphysics, put the point this way:

If all are alike both wrong and right, one who is in this condition will not be able either to speak or to say anything intelligible; for he says at the time both "yes" and "no." And if he makes no judgement but "thinks" and "does not think," indifferently, what difference will there be between him and a vegetable?(end quote)

What difference indeed. Without the law of noncontradiction, we can't believe things to be one way rather than another. But if we can't believe things to be one way rather than another, we can't think at all.

Logic is the study of correct thinking. As a result, the laws of thought are often often referred to as the laws of logic. Anything that violates these laws is said to be logically impossible, and whatever is logically impossible can't exist. We know, for example, that there are no round squares, no married bachelors, and no largest number because such things violate the law of noncontradiction - they attribute both a property and its negation to a thing and are thus self-contradictory. The laws of thought, then, not only determine the bounds of the real. Whatever is real must obey the law of noncontradiction. That is why the great German logician Gottlob Frege called logic "the study of the laws of the laws of science." The laws of science must obey the laws of logic. Thus, von Daniken is mistaken. Some things are logically impossible, and whatever is logically impossible cannot exist." (Page 16 - 17)

"Psychokinesis, the ability to move external objects with the power of one's mind, seems to be physically impossible because it seems to imply the existence of an unknown force. Science has identified only two forces whose effects can be felt over long distances: electromagnetism and gravity. The brain, however, is not capable of producing enough of either of these forces to directly affect objects outside of the body. So psychokinesis seems to violate the laws of science.

The notion that we have been visited by ancient astronauts or aliens from outer space seems technologically impossible because the amount of energy needed to travel to the stars is astronomical. In Beyond Star Trek, physicist Laurence Krauss considers some of the practical problems associated with interstellar travel. A spaceship traveling to Alpha Centauri the nearest star) at 25 percent the speed of light and using conventional rocket fuel, he claims, would have to carry more fuel than is available from all the matter in the universe.

A spaceship using an unconventional propulsion system like warp drive would require a generator capable of producing energy equivalent to 10 billion times the mass of the visible universe. So if Krauss is right, interstellar travel will probably forever be beyond our technological capabilities.

Contrary to what Von Daniken would have us believe, it is possible to apply the word impossible to some things. Some things are logically impossible, others are  physically impossible, and still others are technologically impossible. And as Krauss's example of interstellar travel shows, even if something is physically possible, it doesn't necessarily follow that it will ever be actual. The principle that should guide our thinking in these matters, then is this:

Just because something is logically or physically possible doesn't mean that it is, or ever will be, actual.

If logical or physical possibility were grounds for eventual actuality, we could look forward to a world containing moon-jumping cows or egg-laying bunnies. To determine whether something is actual, we have to examine the evidence in its favor.

There are those, however, who measure the credibility of a claim not in terms of the evidence for it, but in terms of the lack of evidence against it. They argue that since there is no evidence refuting their position, it must be true. Although such arguments have great psychological appeal they are logically fallacious. Their conclusions don't follow from their premises because a lack of evidence is no evidence at all. Arguments of this type are said to commit the fallacy of appeal to ignorance. Here are some examples:

No one has shown that Jones is lying. Therefore he must be telling the truth.

No one has shown that there are no ghosts. Therefore they must exist.

No one has shown that ESP is impossible. Therefore it must be possible.

All a lack of evidence shows is our ignorance; it doesn't provide a reason for believing anything. "" (Page20-21)

"If a lack of evidence against a claim actually constituted evidence for it, all sorts of weird claims would be well founded. For example, the existence of mermaids, unicorns, and centaurs - not to mention Bigfoot, the Loch Ness monster, and the abominable snowman - would be beyond question. Unfortunately, substantiating A claim is not that easy. The principle here is this:

Just because a claim hasn't been conclusively refuted doesn't mean that it is true.

A claim's truth is established by the amount of evidence in its favor, not by the lack of evidence against it.

In addition, the strategy of placing the burden of proof on the non-believer is unfair in so far as it asks him to do the impossible, namely, prove a universal negative. A universal negative is a claim to the effect that nothing of a certain sort exists. Suppose it's claimed that there are no white ravens. In support of this claim, suppose it's pointed out that no one has ever reported seeing a white raven. From this it doesn't follow that there are no white ravens, for no one may have looked in the right place. Or if somebody saw one, it may have not been reported. To prove a universal negative, you would have to be able to exhaustively investigate all of time and space. Since none of us can do that, it's unreasonable to demand it of anyone. Whenever someone proposes something novel - whether it be a policy, A fact, or a theory - the burden of proof is on her to provide reasons for accepting it.

It's not only true believers who commit the fallacy of appeal to ignorance, however. Skeptics often argue like this: No one has proven that ESP exists; therefore it doesn't. Again, this is fallacious reasoning; it's an attempt to get something for nothing. The operative principle here is the converse of the one cited above:

Just because a claim hasn't been conclusively proven doesn't mean it is false.

Even if no one has yet found a proof of ESP, we can't conclude that none will ever be found. Someone could find one tomorrow. So even if there is no good evidence for ESP, we can't claim that it doesn't exist. We can claim, however, that there is no compelling reason for thinking that it does exist. " (Page 21-22)

"Just because you can't explain something doesn't mean that it's supernatural. " (Page 24)

SUMMARY

It is not the case that anything is possible, as some people claim. Anything that violates the laws of logic is said to be logically impossible, and whatever is logically impossible can't exist. Such things as round squares and married bachelors are logically impossible, for they attribute both a  property and its negation to a thing and are therefore self-contradictory. Many extraordinary things such as ESP, alien abduction, and out-of-body experiences are logically possible - they are not self-contradictory. But if they violate the laws of science, they are physically impossible. Anything that is inconsistent with the laws of science, or nature, is physically impossible; and visitation by aliens from outer space seems to be technologically impossible. The principle to keep in mind about such things is that just because something is logically or physically possible doesn't mean that it is, or ever will be, actual.

 We must approach claims of physical impossibility with caution, for it isn't phenomena themselves that contradict physical law, but rather our theories about them - and our theories may be mistaken. " (Page 31)