Logical Gal and why your major premise matters

20 Jan

Premise 1 – All exercise benefits the body

Premise 2 – Stretching is an exercise

Conclusion – Therefore, stretching benefits the body

The major premise is the first one listed above, in this example:  All exercise benefits the body

The way deductive logic works is this: if the major and minor premises are TRUE and if the syllogism conforms to rules for correct formation (validity), then the conclusion is both predictable and true. Without going into any further discussion about validity, I want to focus on WHY one’s major premise, in general, can have a weighty effect on one’s conclusions.

Consider a married couple who trust each other.

Let’s imagine a situation where it’s reported to the husband (Bob) that his wife has been seen having some tête-à-tête discussions with a man.  The implication is that maybe the wife (Sue) is having an affair.

Depending on Bob’s major premise about his wife and their marriage, his conclusions will be different.

Possibility # 1:

Overarching presupposition or major premise:

Premise 1:  (overarching major assumption) My wife is faithful to her word and her commitments and loves me completely

Premise 2: (the circumstances) – But she has been seen with another man

Conclusion: since I know that she is a faithful gal and loves me, there must be a good explanation for who that other man is.

Here’s the other major premise and subsequent conclusion

Premise 1: My wife might not be totally committed to me or to our marriage

Premise 2: She’s been spotted talking with another guy

Conclusion: She probably is cheating on me

Do you see how what we do with new information depends on the contexts we hold?  Same circumstance in both cases – the wife is seen meeting with another man.  The conclusions vary due to the original major premise or pre-supposition.  Sometimes we are not even aware ourselves of the assumptions we carry with us.  They are implicit, subconscious.  But they powerfully affect our lives!

Just for fun, what could be possible scenarios that would explain Sue’s conversations with a strange man? Maybe she was talking….

  • with a craftsman to plan a special birthday gift for her husband
  • with a potential care-giver for her aging father
  • with their son’s new soccer coach about his skills

If we move into a more spiritual plane, how might our pre-suppositions about God affect our reactions and conclusions to disappointment, illness or acts of violence we encounter in life? Have you ever met someone who claims that God must not be good or all-powerful if He lets evil happen?

Their major premise probably goes something like this:

God is good and almighty if He answers my prayers according to my desires

Question: Have you ever drawn a conclusion about someone or something that turned out wrong? How did your assumption or major premise impact your conclusion?

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