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Deductive Reasoning

Image result for laundry hamper


Would it be preferable if we could live life and make pressing decisions on a purely deductive basis?

Suppose I’m wondering whether today is actually Saturday, thus whether I should get busy with my laundry
as per my rule. I might create a perfect syllogistic chain to answer this question.

By my count, such a chain requires three premises and one definition. For example:


P1) In this neighborhood, every day on which the trash collectors arrive is a Friday.
P2) Yesterday was a day on which the trash collectors arrived.
C1) Thus, yesterday was a Friday.
D1) “Yesterday” means the day that immediately preceded today.
C2) By (C1) and (D1), The day that immediately preceded today was a Friday.
P3) Every day that was immediately preceded by a Friday is a Saturday.
C3) By (C2) and (P3), Today is Saturday, QED.


Now … where is my hamper?


Obviously, we don’t think like that. Nor is it a desideratum. Life would be a very ponderous business if
we did. So when are such syllogisms useful? Sometimes it is worth while setting them out for
purposes of clarity. Consider something weightier, the proposition that all substantive moral judgments
must be in error because there is no underlying moral reality to which they refer. It is valuable
in grappling with all that is at stake there, to employ the explicitness that a formal structure allows.

"Substantive moral judgments" (SMJ) in the pertinent sense we can take to be the set of all such judgments
as assign a morally weighted predicate to a specific fact or action as subject, such as "taking the property
of another person without permission is wrong" or "is right" or "can be wrong or right depending
on further circumstances" for that matter. We'll need to work that definition into our chain, just as a
definition of "yesterday" played a critical role above.

P1) People only disagree over judgments when they take judgments to represent facts in the world.
P2) People do commonly disagree over the SMJs they/we make.
C1) Thus, people understand SMJs to represent facts in the world.
D1) SMJs assign a morally weighted predicate to a specific fact or action as subject.
C2) By (C1) and (D1), there exists an understanding among people who make SMJs that some morally
weighted predicates can accurately be assigned to facts or actions in representing facts in the world.
P3) But the predicates such as "wrong" or "right" used in SMJs never represent facts in the world.
C3) By (C2) and (P3) all common moral judgments are in error, QED.

This would need some further work to be made as air tight at the laundry example. But even in this
still crude form, it does serve the cause of clarity. If becomes clear that if I want to disagree with C3,
I'm going to have to disagree with one or more of the premises. I could disagree with the nature of
disagreement itself (P1) -- although that would seem to me an odd move. I could disagree with (P2)
and try to explain why it is that people only THINK they are disagreeing over SMJs but really
aren't.

I could quarrel with the definition of SMJs, by for example contending that the subject.
predicate structure that definition employs is misleading.

Or, I could disagree with (P3). There we seem to have zoomed in on the point.


Comments

  1. Let's suppose for the sake of argument that no underlying moral reality exists. That makes SMJs "wrong" in one sense, but not in another. They may be right within the system of morality that we adopt. Suppose that we adopt a system of morality that includes the axiom that inflicting pain or death on other sentient beings, without their consent, is wrong unless it is justified by some good that it yields, other than any pleasure that the person who inflicts it derives from it. Applying this axiom, we might conclude that expressing road rage by shooting another driver who cut us off is not justified and therefore is immoral. I would contend that, whether or not the axiom represents a fact in the world, the conclusion is right within the system of morality we have adopted. (Of course, to reach this conclusion, we'd also need an axiom that defined "justified.")

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