So... you've signed up for an online logic and critical thinking class. It's only fair for me to point out the positives and negatives of such a class up front. The negative is obvious: I can't give you the personal attention with the more difficult material that you might get in a face-to-face class. However, this negative is counterbalanced by the fact that we have the full resources of the web at our fingertips. This is a class about reasoning and the web has countless examples of good and bad reasoning, from high-brow news websites to anonymous blogs. The lectures will often contain outside links and some of the discussion questions ask you to research other websites.

But now, it's time to get more specific about the subject matter itself. This is a philosophy class. When many people hear the term "philosophy" it calls to mind deep thinkers, pondering the nature of the world or the meaning of life. How does this relate to critical thinking? Well, the answer is that philosophy is a very general, wide-ranging discipline. Philosophers don't leave many areas of human knowledge unexplored (in fact that distinction between science and philosophy has not always been clear and to some extent it's still not). So, while it's true that philosophers ponder the meaning of existence, they also ponder the underlying principles of language and writing, and this will be our focus for this class. To see an outside justification for the study of philosophy, see the webpage The Importance of Philosophy. The page also shows you a way to categorize the branches of philosophy. The material in this class falls mostly under the category epistemology--the theory of knowledge.

Since this is the introductory lecture, it is necessary to define some terms and lay some ground rules. (Note: to re-enforce the concepts, these lectures sometimes repeat what is in the book. However, there is also new material--the idea is to read both the lectures and the assigned chapters. Often the lecture will clarify something in the book.)

Critical Thinking

Although humans have done many great things with their intelligence, they have also done many foolish things. Even very smart people can be unreasonable.

Sometimes critical thinking is unnecessary--when you're enjoying a beautiful sunset, for example--but other times it's imperative, like when buying a new car or deciding whether to move to a new city or town.

Here is a definition: critical thinking is the careful application of reason in the determination of whether a claim is true.

Critical thinking is thinking about thinking. Our actions depend on what thoughts, beliefs, or ideas we’ve accepted. This means that it’s important to accept the right thoughts as a guide to action. Think about that for a minute. Just consider someone who believes that "family comes first." Based on this abstract belief, we can predict how this person might act. Faced with a choice between her own happiness (like moving to another state for a great job) and her family's well-being (being a good daughter), she is likely to choose the latter. What we believe influences our actions, even if those beliefs are abstract. Often we're not even aware of the abstract beliefs we've accepted—becoming aware of such beliefs is one of the advantages of this class and other philosophy classes. In other words, our beliefs are unconscious. In fact, the biases discussed in the 10th edition of the book are clear examples of the way we are influenced by unconscious beliefs and tendencies.

Critical thinking affects us at all levels of decision-making, from insignificant decisions to significant ones. The wise person is the one who knows how to minimize his errors in critical thinking in all areas of life (there is no way of abolishing them completely--we are imperfect beings after all).

Critical thinking demands that we assess our beliefs and the beliefs of others. Sometimes people see questioning the beliefs of others (particularly close family members) as rude or out of line. But projecting someone’s beliefs to scrutiny is not necessarily a personal attack. We'll discuss this more as we get further into the class.

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Claims and Issues

Claims (or statements) can be true or false. It’s true that a bachelor is an unmarried man. It’s false that the earth is the second planet from the star we call the sun. Some claims are either true or false but we don’t have the information to know which. “There is life on other planets" is an example of such a claim. It's possible that future developments in space travel will show this claim to be true or false, but for now we don't know.

Some claims do not need investigation and are obviously true or false. It’s obviously false that dinosaurs still roam the earth. It’s either true or false that it’s raining outside and all you have to do to know is look outside.

There are subjective and objective claims. A subjective claim depends on the opinion of a person. "Vanilla ice cream is the best" is a subjective claim. It's not objectively true that vanilla ice cream is the best. An objective claim does not depend on what anyone thinks. "Renee thinks vanilla ice cream is the best" is objective because it's either true or false that Renee thinks this. Notice the difference between the two, despite the fact that both have similar content.

Issues are questions we raise about claims. If we ask whether a claim is true or false, we are raising an issue. To think critically about a claim is to call it into question and make it an issue. Notice that an issue always asks whether something is the case; it does not say that something is or isn’t the case. For example, imagine that someone says the following: “The central government has too much power. Just the other day they forced a local business to shut down.” Now, the issue in this sentence is whether the federal government has too much power, and the person being quoted is taking a stand on that particular issue.

To assess a claim, it’s good to know under what conditions it could be true or false. Does God exist? And if so, which God or how many? Are there parallel dimensions? Is there a Spaghetti Monster? Can we even conceive under what conditions some of these questions would be true or false? The answer to some questions depends on definitions. For instance, some people define God as "beyond the physical world." Here God is defined in such a way that no evidence or argument could every prove that He exists or does not exist. In philosophy, such questions fall under the category of "metaphysics."

Even some less abstract claims are hard to assess, like this one: it is in human nature to seek power and dominate others. Many of you, I'm sure, have heard (or believe) this claim. What sort of evidence is needed to support it? Could you do surveys to support it? How would they look? Would everyone be convinced?

Here’s where this all gets personal. In accepting a claim, you personally have to have reasons for accepting it. If believing that what is written in the bible is the word of God is sufficient reason for you to justify your belief in God, then so be it. But other people might need more. (This is in no way critical of religion; it is only an example.)

Arguments are produced when we give a reason for thinking that a claim is true. Determining whether an argument is good or bad is the crux of this class. Below are some more key terms.

Premise: a claim that is offered as a reason for believing another claim.

Conclusion: the claim for which the premise is supposed to give a reason.

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Whether an argument is good depends on whether the premise really supports the conclusion. For a premise to provide good support, it must be true and relevant to the conclusion.

Arguments are not feuds or verbal fights between people. Arguments don’t even require two people (contrary to popular belief). We make arguments to ourselves all the time. For example, when we decide not to go Christmas shopping on a certain day because there will be too many people we are making an argument. Here the premise is: There are too many people out in the stores today. And the conclusion is: Therefore, I will not go Christmas shopping today. You might not say it this way to yourself, but at the base of your thinking is an argument that we can assess.

Arguments are not explanations, descriptions, value judgments, etc. Persuasion and argument are not the same thing. People don’t always use arguments to persuade. For example, if you say "I hate vanilla ice cream" you are not making an argument; it's a value judgment. There is no conclusion being supported by a premise or claim. Notice, however, that a value judgment can be part of an argument if it is supported by good reasons. For example if you say: "Everytime I eat vanilla ice cream I almost throw up. Therefore, I hate vanilla ice cream." This is now an argument since the value judgment is not alone, and is a conclusion supported by a premise.

There are two kinds of arguments: deductive and inductive. You might have heard these terms before, but now you're going to learn what they are in more detail. We will be studying them in the next two lectures. But just to prepare you, here are a couple of definitions. Deductive arguments provide certain conclusions while inductive arguments provide the best possible support for a conclusion. So, while deductive arguments are certain, inductive arguments are based on likelihood. If this doesn't make sense yet, hang in there. You should start to get it after the next few lectures.

But back to arguments in general. There are certain words that let you know you are dealing with a premise or a conclusion. Here are some premise indicators: because, since, as we can see, etc. Here are some conclusion indicators: therefore, thus, so, etc. Here is an example:

As we can see Japanese cars run much better than American cars. Therefore, I'm going to buy a Japanese car.

Notice that premise and conclusion indicators are only a guide; they are not always present in an argument. For example: Japanese cars run better than American cars. I'm getting a Japanese car.

The book points out that critical thinking is significant in moral matters, even when there are clear differences of opinion and interpretation. But it does not matter so much with likes and dislikes (movies, books, ideas of beauty, etc.). You can have a shouting match with someone about who makes better movies, Martin Scorcese or the Cohn Brothers but there is really nothing to be gained or lost from such an encounter (this is itself, of course, is a value judgment). However, arguing about whether or not to torture prisoners of war is a serious matter that deserves careful consideration.

Sometimes we are more apt to listen to people who are close to us, like our parents and friends. But we should evaluate claims on the merits of those claims, not on the merits of those making the claims. The opposite is also true. Sometimes we tend not to listen to those who are not considered authorities. But we should evaluate these peoples' claims, not their appearance and demeanor.

We must learn to distinguish between persuasive and rhetorical tricks and genuine support for a claim or claims. Psychological tricks will be dealt with when we discuss fallacies later on. But again, the cognitive biases from the book are relevant here.