Should we ever trust anyone’s expertise? The “appeal to authority” is a well-known fallacy (nonrational way to reason) and some people claim that all appeals to authority are fallacious. I was once told that my religion is science because I trust the expert opinion of scientists, so apparently that person doesn’t think scientists should be trusted. I will explain why we should often trust expert opinion and we have little choice but to often do so. (more…)
July 16, 2013
Critical thinking is an educational domain concerned with good reasoning. In the broad sense critical thinking includes both formal and informal logic. The narrow sense of critical thinking (as it is often taught in universities) is primarily concerned with (and often equated with) informal logic. Formal logic primarily involves the study of logical systems, logical axioms, logical consistency, and logical validity; and informal logic primarily involves argument identification, argument interpretation, unstated premise identification, and informal fallacies. (See “What is Logic?” for more information.) Critical thinking is generally not thought to be merely about memorizing logical facts. Instead, it is also thought to involve the development of critical thinking skills, the critical thinking attitude, and critical thinking virtues. The purpose of this paper is to briefly discuss critical thinking skills, the critical thinking attitude, and critical thinking virtues. (more…)
July 8, 2013
I will discuss what unstated premises are, how to identify them, and how to determine what they are.
What are unstated premises?
Unstated premises are premises that a deductive argument requires, but are not explicitly stated. Deductive arguments are popular and can be rationally persuasive, but people don’t always state all of the premises that their deductive arguments require. These premises can be called “unstated premises,” “missing premises,” or “hidden assumptions.” For example, consider the following argument: (more…)
July 1, 2013
I am now working on more definitions for the Comprehensible Philosophy Dictionary. What follows are several new definitions that will be added to it. Let me know if anything should be improved. (more…)
June 13, 2013
What’s the point of a rational argument? To give someone a good reason to believe something. A sufficiently good argument gives us a good reason to believe something is true. It is better for us to have beliefs that are supported by good arguments in the sense that they are more likely true based on our limited understanding of the world, but it is possible for them to be false. (more…)
May 26, 2013
Science has occasionally appropriated philosophical fields. Physics and psychology were originally discussed by philosophers rather than scientists. Right now ethics is considered to be a philosophical domain, but we could imagine science taking over the field. Will ethics ever be taught in a science class? Will we learn right and wrong from natural science?
People who reject that we could one day have a moral science generally do so due to skepticism, the gap between facts and values, and the is-ought fallacy. I will respond to these concerns and explain why I don’t think any of them are conclusive. (more…)
May 13, 2013
A formal logic class or textbook should teach us ways to know when an argument has a valid argument form, and that can take a significant amount of time to learn. I encourage everyone to learn formal logic one way or another because it is of central significance to rational argumentation, and it is not something we spontaneously understand instinctively or through personal experience. Perhaps the first philosopher to understand formal logic and the importance of validity was Aristotle, and philosophers would have liked to understand it sooner. It was a great achievement because it can be so difficult to figure out on our own. Even so, we can learn a lot about valid argument form very quickly. I will explain why we need to make sure our deductive arguments are valid, give examples of valid argument forms, and explain how we can improve our arguments. (more…)
May 5, 2013
The problem of evil refers to the fact that certain traditional views of theism involve contradictory beliefs. The problem is that God should be willing and able to make sure evil doesn’t exist, but evil exists. Some theists argue that atheists can’t reject the existence of God based on the problem of evil because atheists would then have to assume objective morality exists, but objective morality requires God. I will argue that the theist’s argument is irrelevant in consideration of one argument against one type of traditional theism, but it is somewhat relevant against another. Even so, both arguments are unsound. (more…)
May 2, 2013
April 19, 2013
Many people think philosophers aren’t experts, that we can’t really know anything about philosophical issues, or that everyone’s opinion is equal concerning philosophical issues. Philosophical issues are often narrowly understood to be those concerned with the nature of reasoning, knowledge, morality, or reality; and many people say we can’t know anything about such issues. I will argue that we can know something about philosophical issues, which suggests that there can be expert philosophers, and that not everyone’s philosophical opinion is equal. We do seem to know something about philosophical domains and it is plausible to think we can give meaningful philosophical arguments within these domains. Such a position is actually more consistent with how people think about the world. (more…)
March 21, 2013
Some of my key blog posts about propositional logic have been organized a free ebook. This ebook can greatly help people understand the importance of logically valid arguments and better understand logical form.
The focus of this book is propositional logic. I discuss the meaning of “logic,” the importance of logic, logical connectives, truth tables, natural deduction, and rules of inference.
March 6, 2013
Recommended reading: What is Logic?
Why is logic education important? The main question here is what the real point of logic education is. The real point of logic is not to teach people how to be logic professors, or to increase test scores, or to impress potential employers. Philosophers and mathematicians were very interested in understanding logic long before it was taught in universities precisely because of how important it is. Why is logic so important? The answer is that logic helps us better understand good arguments—it helps us differentiate between good and bad reasons to believe something. We should want to have well-justified beliefs. We want to know what we should believe. Understanding good argumentation helps us understand when we should believe something, and understanding logic helps us understand good argumentation. (more…)
February 26, 2013
Do extraordinary claims require extraordinary evidence? Is there a burden of proof against extraordinary claims? Should we literally assume that something extraordinary doesn’t exist until it is proven to exist?
Many people say that those who claim that bigfoot, ghosts, and gods exist are making “extraordinary claims” and we should reject the existence of these things because we don’t have enough evidence for them.
What does ‘extraordinary’ mean? It refers to claims that conflict with what we think we know about the world. Many claims are extraordinary because they are extreme (likely false) or potentially impossible. (more…)
February 20, 2013
This is part 6 of a series. Links to the other parts of the series are above.
The straightforward way to construct proofs using natural deduction is called the “direct method.” Every line of that type of proof is validly deduced from the premises and rules of inference. Every line of such a proof could be considered to be true as long as we consider the premises to be true. However, there are two other strategies: The conditional proof and the indirect proof. Both of these types of proofs introduce an additional premise that is assumed to be true “for the sake of argument.” (more…)
February 19, 2013
This is part 5 in a series. There are links to the other parts of the series above.
Natural deduction is used to give proofs of validity by showing all the steps in reasoning required. In this case natural deduction uses rules of inference to allow us to reach conclusions from statements of propositional logic. (more…)
February 12, 2013
At some point you are likely to hear about how giving arguments is rude and we would all get along better without arguing. Arguing is often thought to be a shouting match or hostile disagreement of some sort. However, argumentation is central to thinking rationally and critical thinking. The success of natural science could not exist without it. Yes, some arguments are disrespectful, but not all of them are. (more…)
January 29, 2013
January 22, 2013
It can be difficult to find anyone willing and able to engage in rational debate, but it is something I think we should aspire to having. Many people refuse to engage in rational debate because they find it offensive or they would rather engage in name calling. I believe that rational debate has a lot to offer. It can help us better understand how to reason properly and to develop critical thinking skills. Rational debate is important to everyone who wants to know what they should believe about a controversial issue because we need to know if there’s a good argument in favor of a belief. (more…)
January 19, 2013
Truth tables are an important tool for evaluating statements and arguments. We can create our own truth tables using following steps:
Translate statements of ordinary language.
Break all complex statements into smaller parts.
Determine how many columns are required.
Determine how many rows are required.
Determine the truth values of statement letters.
Determine the truth values of complex statements.
I will illustrate how to follow these steps by using an example. In particular, I will show how we can make a truth table of an argument to find out if the argument is logically valid. (more…)
January 14, 2013
Truth tables are visual aids to help us determine all the truth value possibilities of various statements. Learning about truth tables can help us better understand logic. Truth tables are used to define logical connectives, and to help us identify various distinctions (such as tautologies, self-contradictions, consistent statements, equivalent statements, and valid arguments).