To take vitamins or not, that is….not the question today

2 Sep

Imagine that your office mate has just asserted the most ridiculous conclusion that you have ever heard: that taking vitamins is a waste of time and money!    

    VERSUS ………….    

You, who pop a handful of carefully selected ‘food supplements’ SWEAR by the efficacy of these expensive pills.  After all, how many sick days have YOU taken in the past five years?

But before you give her a piece of your mind, calm down and ask her to explain her claim.  Remember that she who advances a proposition, a claim, a conclusion, an assertion MUST give her evidence, her reasons, her method of arriving at this thought.  If you want some help, click on the link here for a resource by Greg Koukl.  Great Book to Help who does what in an argument

After listening to your office mate, you realize that before you can even GET to thinking about the truth or falsity of her conclusion, you have to guide her in formulating her reasons.  After some coaxing, here is what she has offered:

  • Food provides enough vitamins and minerals to stay healthy
  • No manufactured vitamins can provide the same quality of benefit found naturally in food.
  • Therefore, taking vitamins is a waste of time and money

Your friend obviously needs some help in identifying her terms and organizing her argument into syllogisms that are built on 3 terms each.

But before you pull out your pencil and start sketching logic charts, we can just refer to Rule # 7 to show that her argument is invalid:

What is the quality of premise # 1 (‘food provides enough…’ )?   It is AFFIRMATIVE

What is the quality of premise # 2 (‘no manufactured…’)?  It is NEGATIVE

Rule # 7 of the Seven Rules for Testing Validity states that if one of the 2 premises is negative, then the conclusion MUST be negative.  Your friend has NOT stated a negative conclusion but the AFFIRMATIVE statement that ‘Taking vitamins is a waste of time and money’

Since the argument is invalid based on Rule # 7, you’re off the hook from giving your 2 cents worth.  But spend some time helping her tease out her reasons and re-articulating them and then checking to see that is what she means.  She’ll gain respect for you as a gentle friend and maybe SHE might see some holes in her reasoning.

Meanwhile play around with what YOU believe about vitamins and craft YOUR argument following the 7 rules.

Here they are in summary.  Next time we’ll build an argument about vitamins that is VALID.

Every syllogism to be valid (that is correctly formed), must comply with all seven rules:

  1. Has 3 and only 3 terms
  2. No middle term in the conclusion
  3. If a term is ‘distributed’ in the conclusion, it must be ‘distributed’ in one of the premises
  4. The middle term must be distributed once.
  5. No conclusion can be drawn from 2 negative premises
  6. If the 2 premises are affirmative, the conclusion MUST be affirmative as well
  7. If one of the 2 premises is negative, then the conclusion MUST be negative as well.

Keep thinking! 

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