Tag Archives: Logic

God uses logic and evidence

28 Jul

The handwritten note peaked out between flyers and magazines as if to say, ‘Don’t miss me!’  I scanned the return address, quickly recalling a former student from Virginia.

Along with the graduation announcement and senior photo, he wrote an account of the four years just completed at this classical Christian school in Virginia.  I rejoiced to read his description of the long-term effect our 8th-grade logic and reasoning curriculum had exerted on his life. Encouraged and guided in HOW to question and to think logically had sparked the fuse that propelled him out of complacency in his studies.  Apparently, after I departed, hunger to grow intellectually had gripped him, for he had gained vision and a purpose for learning.  That kind of feedback would energize anyone!

I do give thanks that a middle school logic class birthed this young man’s interest in knowledge and ideas. Certainly, students need to know how to reason well and express themselves clearly in order to advance in academics.  But clear thinking is vital to all of us, even Christians.

Why do I say Christians must know how to express themselves clearly and evaluate arguments accurately?  Contemporary society bombards believers with the false and disreputable view that faith and science or faith and reason are antithetical.  Not true! But we people of the Book must be taught how to gently push back with the truth.  And that takes information and practice, in essence: ‘skill’.

Humans are not born knowing how to reason well. But just like my former 8th-grade student, we all can be taught and equipped with some basic tools and ways of evaluating both written and spoken thoughts.

Why is it important for Christians to use logic? Just today, in Isaiah 41, I read verse after verse where God exhorted His people to argue or reason on behalf of the efficacy of idols. Consider these 3 verses, 21-23 (NLT):

Present the case for your idols,”
    says the Lord.
“Let them show what they can do,”
    says the King of Israel.
22 “Let them try to tell us what happened long ago
    so that we may consider the evidence.
Or let them tell us what the future holds,
    so we can know what’s going to happen.
23 Yes, tell us what will occur in the days ahead.
    Then we will know you are gods.
In fact, do anything—good or bad!
    Do something that will amaze and frighten us.” 

God doesn’t want His people to fall back on ‘blind faith’.  He wants us to believe Him, count on Him, trust Him and thus obey Him having gained true knowledge. Like scientists who collect, observe, and study evidence we also must reason to likely conclusions. Listen to how He chides Jacob in Isaiah 40:26-28, encouraging the people to consider the evidence He provides:

Look up into the heavens.
    Who created all the stars?
He brings them out like an army, one after another,
    calling each by its name.
Because of his great power and incomparable strength,
    not a single one is missing.
27 O Jacob, how can you say the Lord does not see your troubles?
    O Israel, how can you say God ignores your rights?
28 Have you never heard?
    Have you never understood?
The Lord is the everlasting God,
    the Creator of all the earth.

‘Use the eyes, ears, and mind I’ve given you!‘ God seems to argue. From God’s perspective and His true knowledge, only willful obstinacy and sinful desires can explain Jacob’s irrational behavior, since they had been given ample visual and historical proof.

My former logic student probably doesn’t know how learning (and subsequently teaching) logic also changed my life. I had never been taught to think or to reason. No course in grade school or college had guided me in how to begin to evaluate others’ assertions, let alone construct my own reason-based logical argument.  Those six years at that classical Christian school altered my life for good!  I grew into a better reader, listener, thinker, and writer.

Reading this young man’s sweet note re-ignited MY passion for advocating for thinking. As the bumper sticker trumpets:

Critical Thinking - national deficit

 

How recognizing a fallacy helps sniff out a poor argument

10 May

All cows have four legs

My dog Fido has four legs

Therefore, Fido is a cow

Pastor John Piper explained in a rebroadcasted sermon how high school geometry had grounded him in clear thinking.  Mathematical laws, one leading to a next, trained him to use deductive reasoning.  With practice in drawing valid and true conclusions, he developed a ‘nose’ for truth, as he put it.  The practical effect for him has been to alert him to ‘fishy’ conclusions that stink, that is they don’t add up, given the premises provided.

Looking at the syllogism above, we notice something and we ‘smell’ something:

  1. Premises 1 & 2 are in fact TRUE – cows have 4 legs and dogs normally do as well
  2. But we know that the conclusion is FALSE.  Our dog Fido is NOT a cow.

For me, the quickest way to explain why our sense of ‘fishiness’ is spot on, is to draw out each premise.

Take All cows have 4 legs.

Step 1:  draw a circle – label it Creatures with 4 legs.

2 cirlces

Step 2: draw a smaller circle somewhere inside the first circle.  This represents ALL COWS.  Every cow that ever WAS, IS, WILL BE  is in that circle.  (assuming no handicapped cows)

Step 3:  Mark an X in the big circle called, Creatures with 4 legs.

Circles with X

Do you spot the problem?  We don’t know where to place Fido.  Does he belong in the circle of cows? or out of the circle of cows?  From the information given, the 2 premises, that cannot be determined.

Therefore, the conclusion is false.  Why?  Because the new premise that ‘Fido is a cow’ assumes too much.  It might be, but it might not be.

There is of course, a technical way of categorizing the validity of the syllogism.  But for me, just sketching it out is simplest.

When I taught in a classical Christian school in Yorktown, Va, logic was a mandatory class for 7th and 8th graders.  I instructed the younger students in the joy of spotting fallacies (much to the annoyance of their parents who thereafter had to be on their guard!).  The 8th graders were at the perfect age to begin to understand how to analyze and formulate good arguments.

I believe that this tool in clear thinking is invaluable to young teens AND adults.  This kind of knowledge is powerful and builds confidence when they head out into a world such as ours:

Woe to those who call evil good, and good evil: who substitute darkness for light and light for darkness; who substitute bitter for sweet and sweet for bitter!  Woe to those who are wise in their own eyes and clever in their own sight!  Isaiah 5: 20-21 (NASB)