If I had to choose the "If You're Only Going to Read One Thing on Dead-Logic, Read This" blog entries, my gut would want me to say this series is the one. I'm not sure whether my mind agrees with my gut, but I will say that these next few entries will showcase the critical thinking tips and tools that I've learned over the past two decades (that makes me sound old), and feature some of the foundational principles I learned from two of the biggest influences in my life in this area: Dr. Herman Stark from South Suburban College, and Dr. Gary Burlington (formerly) from Lincoln Christian College. I am indebted to these men more than they know.
The Path of a Critical Thinker
- Logic vs. Reason
- Valid vs. Sound Arguments
- Arguments vs. Conclusions
Many people use the words "logic" and "reason" (and "logical" and "rational") interchangeably, but there is an important distinction. Reason is the mental ability to come to conclusions, draw inferences, make judgments, create arguments and evaluate arguments. Logic is the science or system that evaluates arguments. To use an analogy from the martial arts, reason is like the abilities one has to punch, kick, and apply a particular move, whereas a martial art (like Jiu Jitsu, Karate, or Krav Maga) is the science or system that shows how to utilize and apply such abilities. And, like a martial art, the more one practices using logic, the better one can become.
An argument in logic has nothing to do with a verbal fight. An argument, as it occurs in logic, is a group of statements (called premises) intended to provide support or justification for another statement (called the conclusion). There are only two kinds of arguments: those which actually support the conclusion and those which do not. If the goal of a critical thinker is to evaluate arguments, then understanding how to evaluate them is imperative. Arguments must be assessed by both form and content. Arguments that have correct form or structure are called "valid" arguments. A valid argument is one in which, if the premises are true, the conclusion must be true. Take for example this classic syllogism:Premise 1: All men are mortal. Premise 2: Socrates is a man. __________________ ∴ Socrates is mortal.
This argument is valid; that is, this argument has proper structure such that, if the premises are true, then the conclusion must be true as well. If all men are mortal, and if Socrates is a man, then he must be mortal. One can almost feel how the conclusion naturally flows from the premises. An argument that lacks proper structure is invalid, even if the premises (and even if the conclusion) are true. For example:Premise 1: Polar Bears are white. Premise 2: Abraham Lincoln was the 16th president of the USA. __________________ ∴ Gay marriage should be legal.
A sound argument is a valid argument with premises which are all true. All sound arguments are valid, but not all valid arguments are sound. A sound argument then is one which has proper structure (i.e., the argument is valid), and has all true premises. Remember, a valid argument is such that the conclusion must be true if the premises are true, and if all the premises are true, then that valid argument is then sound. For example:Premise 1: Whales are mammals. Premise 2: Mammals are warm-blooded. __________________ ∴ Whales are warm-blooded.
Arguments one encounters - particularly in the religion/theology/philosophy/atheism/skepticism realm - will often be much more complicated than these two-premises examples; nevertheless, every argument, whether it has two premises or 200 premises, are either valid or invalid, sound or unsound.
Here is an absolutely essential point to understand in order to be a successful critical thinker: one can reject an argument because it is invalid or unsound and still agree with the argument's conclusion. Rejecting an argument is not the same as rejecting the argument's conclusion. Take the example argument above with the conclusion, "Gay marriage should be legal." The argument is invalid, yet I agree with its conclusion. I just don't agree with the conclusion based on that argument. People in general are more inclined to accept arguments which attempt to prove or justify ideas or beliefs they already support, and become less critical of such arguments in the process. A helpful tip in critical thinking is to always turn the axe of criticism toward the trees of one's own ideological forest. A critical thinker cares about truth, not about towing party lines.