Monthly Archives: February 2015

Leonard-Nimoy_1622089c[1]I was sad to hear about  the passing of Leonard Nimoy. I must admit that I was a Trekkie. I watched every episode of the original series many times, and as a boy I even went to a Star Trek convention in Seattle. It was Mr. Spock who first got me interested in logic, interested enough to take my first logic class as a college sophomore. “Logical decision, logically arrived at.”

The Biconditional Truth Table

Hi Mr. Nance!

I had a student ask me a question about the biconditional in Lesson 5 of Intermediate Logic the other day that had not occurred to me. She asked for written explanation of why if both sides of the biconditional were false then the truth table was true. Conceptually I understood it because of the definition of equivalency and from working through the truth tables, but verbally, I could not give her an example. Could you give a verbal example of each possibility of true and false like you did for the conditional, disjunction, and conjunction? I told her just to memorize the truth values, but honestly it would make more sense if I could give her an example that would explain why. Thanks! Continue reading The Biconditional Truth Table

Logic in the Elementary Years

Greetings! 

I was very curious of your expert opinion about Dr. Craig’s book [Learning Logic] since I would like to prepare my 9 yo and myself for this topic as it is a very big unknown to us. If you are familiar with this book, any feedback that you have about it or logic in the elementary years would be very much appreciated.

Thank you for your kind consideration to this inquiry and may God bless all you endeavors in bringing about His Kingdom now.

Continue reading Logic in the Elementary Years

Logic as a moral imperative

When we claim that a false statement is true or that a true statement is false, this is a moral wrong, called lying. But if we refuse to draw the proper conclusion of a valid argument, I do not know of a similar verb in English, a word that will make clear the ethical nature of such bad reasoning. But that it can be an ethical issue seems undeniable. This appears to be the failing of the Jewish leaders in John 5:39-40, who refused to accept that Jesus was the Christ, and of those who suppress the truth in unrighteousness in Romans 1, who are said to be “without understanding.”

Symbolizing “nor” and “both”

Hello!

The problem today was the difference between using a “vel” for “nor” vs. using a “dot” for nor,  the other was where the parenthesis were when the word both was used.  We (the kids too) saw a difference in a couple of them –  but one looked exactly like the other – with two different symbolic statements.

Any assistance would be greatly appreciated.
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There are two ways to write “neither p nor q”:

1)  ~(p ∨ q)
2)  ~p • ~q

As for the use of “both”, the phrase “not both p and q” should be ~(p • q), whereas “both not p and not q” should be (~p • ~q). So the proposition “Betty and Jon are not both eighth graders”  could be symbolized ~(B • J), while the proposition “Betty and Jon are both not eighth graders” would be (~B • ~J).

Blessings!

Great Books Challenge Lessons 1-4

I have had the honor of being friends with Wes Callihan for nearly thirty years. I actually studied Classical Rhetoric under him in 1989 at the fledgling New St. Andrews, when that now thriving liberal arts college was just a night school meeting in a neighbor’s attic.  I have admired his teaching ability from that day to this: his rich knowledge of history, his infectious love for the classics (especially Homer), and his skill in transmitting some of that knowledge and love to his pupils. Consequently, it is a true delight to be once again his student as I work through this Old Western Culture
video course on the Aeneid.

Continue reading Great Books Challenge Lessons 1-4