Do you take vitamins? Creating an argument in support

4 Sep

Food supplements – to take or not to take, voici la question!

Last time we analyzed an argument by applying the 7th rule for checking a syllogism’s validity.  We showed that if one of the 2 premises is negative, then the conclusion MUST be negative as well.

I asked you to think of how you would argue FOR the position that taking vitamins makes a qualitative positive difference in one’s health.  If we are to formulate an argument in its correct form, we need to comply with ALL 7 rules for validity.

Here they are again in a summary list:

Every syllogism to be valid (that is correctly formed), must abide by 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.

On to constructing OUR argument.  Remember, that when we formulate a syllogism, we start with our conclusion and work backwards.

Here is our hypothetical conclusion in ordinary language:

  • Therefore, taking supplements improves one’s health

Before we go any further, we have to add a quantifier and rewrite the proposition so that a copula appears.  First we reflect  – Do we  intend to defend the assertion that ALL taking of supplements improves one’s health or just SOME taking of supplements?

To be on the safe side, it is more truthful and easier to defend an I proposition, or SOME taking of ‘vits’.  After all, some vitamins might be so poorly made NOT to be efficacious.

Next , in order to uncover the copula, we need to ‘tweak’  our second term resulting in:

Therefore, some taking of supplements is a habit that improves one’s health

Now 2 of the allowed 3 terms pop up clearly.

We can label them and determine the distribution based on our ‘DUDU & UUDDs’ chart.  Remember that a term IN FRONT of the copula is in the subject position and a term which FOLLOWS the copula is in the predicate position.  We determine the TYPE of proposition by the quantifier (All, Some, No, Some…not)

Type of Proposition Subject position Predicate position
A (All) D U
I (Some) U U
E (No) D D
O (Some….not) U D

Another reason for starting to create or analyze a syllogism ‘bottom up’, that is to say WITH THE CONCLUSION, is that the minor term (represented by S FOR THE ENTIRE SYLLOGISM) is always the term that precedes the copula in the conclusion and the major term (represented by P FOR THE ENTIRE SYLLOGISM)  always follows the copula in the conclusion.

Here is our conclusion properly labeled:

I statement – Therefore, some taking of supplements (Su) is a habit that improves one’s health (Pu)

So as we end this discussion, we have the following information about our syllogism:

S term = taking of supplements

P term = a habit that improves one’s health

Next time, we will come up with our 3rd term (see rule 1) which is the M or middle term.

Until next time, keep thinking!

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