Tag Archives: if…then statements

Sobering logic

30 Mar

 

Alfie

What’s it all about, Alfie? You know what I mean,” so commented with subdued irony the Michael Caine character in the 1966 British film, “Alfie”.  A very important thought, maybe this was first time that Alfie had looked beyond the present moment to something more than pleasing himself.

Most human beings, unlike other mammals, DO ask the big questions of life.  Rightly so, for these issues are not whimsical ponderings, but life-altering in their implications and answers.

I haven’t seen the movie, but reading the synopsis of it see this link, gave me a sense of the emptiness of Alfie’s (Alfred) life of womanizing.  I thought about the movie and how people either do or don’t take seriously the metaphysical and very serious matters confronting each of us.

The most important choice any human must make can be framed this way as a conditional major premise:

  • If we have lived attached to Jesus Christ in this life, then we will live together with Christ in the next life (which lasts forever)
The converse is true: 
  • If we have NOT lived attached to Christ in this life, then we will NOT live with Christ in the next life (which lasts forever)

Reality is, a decision must be made in this life.  There is no karma, no second chances once we die.  There are only two paths, one with Christ and one without.

These facts are not my opinions; they come from Jesus himself.  He is the one who declared:

  •  “I am THE way, the truth and the light.” John 14:6a

So think deeply, dear logical Joe and Jane.  As pastor and teacher Dr. R. C. Sproul counsels, ‘This moment counts forever’.

2 roads

 

What if….it rains on my wedding day?

25 Sep

Saturday, it POURED in the Asheville area of Western NC. 

Normally we hike, my husband and I.  But as we went to bed Friday night, Mike gloomily looked up from checking his Weather Bug app and announced, “ 90 % chance of rain!”

So we did a field trip into the Big City of Asheville and walked around in the rain, stopping in at Topps for shoes and sampling good food at Black Bird Café.

On our way home in driving rain, I casually mentioned to Mike, “Pity the poor couple who planned a lovely Fall Wedding OUTDOORS!”    

Come to find out, a colleague at work WAS part of the bridal party in what was to be an outdoor wedding.

“ Hors de question!”  out of the question, as it turned out.

So here’s the syllogism:

If it rains, then we’ll have to move the wedding indoors

It’s raining,

Therefore, we must move the wedding indoors

This is called a conditional syllogism, part of the class of hypotheticals.

We test the validity of hypotheticals differently.

The major premise is the complex one, the “if/then statement” .

The normal categorical proposition that follows the IF – in this case, It rains

is called the Antecedent.  And the proposition that follows the THEN – in this case, we’ll have to moved the wedding indoors is called the consequent

There are 4 possibilities for arranging the minor premise and the conclusion.  Two are valid and 2 are invalid because they assume too much.

Here are the valid ones , side by side, with their names

If it rains, then we’ll move the wedding indoors          If it rains, then we’ll move the wedding indoors

It’s raining                                                                                    We’re not moving the wedding indoors

Tf, we’re moving the wedding indoors                             Tf, it’s not raining

Affirming the Antecedent                                                      Denying the consequent

(Modus Ponens in Latin)                                                         (Modus Tollens in Latin)

To remember which segment to affirm or deny to be valid, I created a silly statement.

“ AA (alcoholics anonymous) meets in DC (Washington) is valid”     

So we can either affirm the antecedent or deny the consequent and have a valid conditional argument.

If however, we propose the other 2 possibilities, we are stuck with INVALID arguments.

If we DENY the antecedent we get the following:

If it rains, then we will move the wedding indoors

It’s not raining                       

Tf, we’re not moving the wedding indoors

This is not valid, because there are OTHER possible reasons one might be forced to move the wedding indoors.  There could be a snow storm…..the beach could have been eroded….the patio of the Historic Inn could have been double booked.

The other invalid version is this:

If it rains, then we will move the wedding indoors

We’re moving the wedding indoors

Tf, it must be raining

Again, there are a range of other reasons that might cause the wedding to moved indoors.  We don’t have enough information to conclude that rain is the decisive factor.

The ONLY fact we had was this:  That if rain came, the wedding WOULD FOR SURE be moved indoors.  No other contingency plans were described in the syllogism.

Listen next time you hear an “if-then” statement and see if you can determine if it’s valid.

By the way, the bride owes a hearty thanks to her bridal party who pulled off the herculean task of last minute decorating inside!!