Monthly Archives: December 2015

#19 – More Christmas

“Santa Claus has the right idea: visit people only once a year.” – Victor Borge

“Roses are reddish, violets are bluish. If it weren’t for Christmas, we’d all be Jewish.” – Benny Hill

“When we were children, we were grateful for those who filled our stockings at Christmas time. Why are we not grateful to God for filling our stockings with legs?” – G. K. Chesterton

“Most people want Jesus as a consultant rather than a king.” – Timothy Keller

The Antichrist and the Beast Syllogism

Mr. Nance,

Regarding question no. 10 on page 252: What is the reason for its invalidity? Does the pure hypothetical syllogism also use the five rules of validity? The argument is:

If he is the Antichrist, then he opposes God’s people.
If he is the Beast, then he opposes Gods people.
Therefore, if he is the Antichrist, then he is the Beast.

Is the Beast major term? And is the Antichrist the minor term? How do we make it into valid categorical syllogism? Continue reading The Antichrist and the Beast Syllogism

Counterexample Challenge

Introductory Logic formally teaches two methods for determining the validity of a syllogism: rules of validity, and counterexamples. The rule that tells us that any AAO-4 syllogism is invalid is this: “A valid syllogism cannot have two affirmative premises and a negative conclusion.” But can we show the invalidity of AAO-4 with a counterexample? Here is the schema:

All P is M
All M is S
∴ Some S is not P

I contend that there is only one way to write a counterexample for a syllogism of that form. I challenge you to write a counterexample to AAO-4. Remember that a counterexample must be the same form, and have true premises and a false conclusion.

Good luck!

Four More Informal Fallacies

Formal logic gives us standards by which we can distinguish good reasoning from poor reasoning. Most often, when someone reasons poorly, they are not making an error in formal reasoning, but rather sidetracking their hearers with an informal fallacy. Informal fallacies are less structured errors made in the everyday use of language.

The Introductory Logic text identifies eighteen different types of fallacies, but of course there are many more ways to go wrong than that. My new rhetoric text Fitting Words includes a few popular fallacies not included in Introductory logic. Let me summarize them. Continue reading Four More Informal Fallacies

#18 – On Christmas

“It is good to be children sometimes, and never better than at Christmas, when its mighty founder was a child Himself.” – Charles Dickens

“Christmas is the only time of the year when people of all religions come together to worship Jesus Christ” – Bart Simpson

“When death is thick upon the world, our lives are thick with play. We laugh because there is something that death does not know or cannot remember. That is Christmas.” – Nate Wilson

“There was only one Christmas; the rest are anniversaries.” – W. J. Cameron