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.”
Monthly Archives: February 2015
Who said this about rhetoric?
“And this skill he will not attain without a great deal of trouble, which a good man ought to undergo, not for the sake of speaking and acting before men, but in order that he may be able to say what is acceptable to God and always to act acceptably to Him as far as in him lies.”
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
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.
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!
Symbolizing Exercise 3, problems 13-15
Hi Josiah,
How do you translate the following words into symbolic propositions?
- “A false proposition is not true.”
- “It is false that a true proposition is not false.”
- “It is true that it is false that a true proposition is not false.”
I am discombobulated. Continue reading Symbolizing Exercise 3, problems 13-15
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.
Why Learn Rhetoric?
The skills learned in rhetoric include gathering scattered particulars of knowledge into a coherent whole, organizing them into a useful synthesis, and then communicating that knowledge and understanding effectively in order to benefit others. Given this, rhetoric teaches us on a small scale how to approach everything in our daily lives with wisdom.
There oughta be a law!
I propose a new fallacy name: Ad Imperium. This fallacy says, “Something must be done. Therefore, the government must do it.”