Whatta you sayin’? – or how to form a proposition

2 Jul
  1. Cats show affection.
  2. Ice cream makes me fat.

What you just read are ‘propositions’.  These statements or sentences are essential building blocks in a logical argument.

Who said anything about an argument?   Actually every time you assert something and give a reason for it, you’re making an argument.  The statements are the ‘propositions’.

Propositions comprise two terms.  One is the subject – what you’re talking about.  The other is what you are saying about the subject!  That term is the predicate.

So in our first proposition, ‘ice cream’ is the subject term and (a food that) makes me fat is the predicate term.

“Hold on a minute”, you say, “where did those 3 other words in italics come from?

Good question!  To look at a proposition clearly, we need to isolate the terms. Therefore, we rearrange it a bit and force a ‘copula’ to emerge.  The ‘copula’ is the neutral verb ‘to be’, but in one of 3 conjugated forms: IS, AM or ARE.

Dogs bark becomes Dogs are animals that bark.

Boys stink becomes Boys are kids who stink.

I sing becomes I am a person who sings.

How do you figure out the word after the copula?  Just ask what kind of set or category of ‘things’ your subject term might belong?  You can choose from several appropriate categories.

Ice cream is a……. food/dessert/snack/treat/concoction/item……. that makes me fat. YOU pick what you think communicates effectively, given the context.  Some fancy logicians might say, “Ice cream is THAT which makes me fat” (Whatever works!)

Something else to consider when looking at propositions – we need to add something to our subject term for accuracy.

Let’s go back to our example – Cats show affection.

  1. 1.   First – add the copula (the ‘is, am, are’ form of the verb TO BE) Cats are animals that show affection.
  2. 2.   Now – ask yourself this:  do ALL cats show affection?  Do SOME cats show affections?  Do NO cats show affection or do SOME cats NOT show affection?

What I’m asking you to discern is called the quantifier.  Too often we inaccurately misrepresent someone, a group or something by asserting falsely, “All teens text while driving.”    

-do we truly mean ALL?

-how do we know that EVERY SINGLE teen in the universe texts while driving?

Unless we can document that claim, we owe it to our audience to pull back and say SOME teens text while driving.  That is truthful.  As long as we can prove that ONE SINGLE INDIVIDUAL teen somewhere DOES indeed text while he or she drives, then we are safe to use the quantifier SOME.

Your homework for the week:

1)    Practice ‘translating’ statements/sentences into propositions with a copula (is/ am/ are)

2)    Question yourself when putting FORTH a proposition without a quantifier.  Can you spot how misleading that communication could be?   As my dad used to say, “You can’t make a general statement, you’re not a General!”  He had the correct intention, but not the correct reason.

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