"Junk" Science LO21521

John Gunkler (jgunkler@sprintmail.com)
Thu, 6 May 1999 12:23:52 -0500

Replying to LO21497 --

Michael Schumacher has written a response that will require of me some
serious rethinking -- a task I will take on with joy. So thanks, Michael.
Sorry I'm not ready to respond to the main message yet.

However, there is one minor point that I can respond to and feel I
probably should have written long ago.

When I refer to logical fallacies I am not referring to someone's opinion
about an argument but to well-accepted rules that make what someone says
invalid (or unworthy of belief.) In general an argument may be logically
fallacious in three ways:

In its MATERIAL content -- through a misstatement of the facts.

In its WORDING -- through incorrect use of terms.

In its FORM or structure -- through the use of an improper process of
inference.

Here are some examples (there are many others) of logical fallacies. In
the examples, the letters p, q, r (etc.) stand for any proposition:

1. Fallacy of the Consequent (type 1 -- Denial of the antecedent):

If p is true then q is true. p is not true. Therefore, q is not true.

["If I go to the mall I always buy a toy. I did not go to the mall.
Therefore, I did not buy a toy." -- This is false, however, because I may
have bought a toy at the corner drug store.]

Note: The example above is often abbreviated as follows ... If p then q.
Not p. Therefore not q. [This is taken to mean the same thing as the
longer version above.]

2. Fallacy of the Consequent (type 2 -- Affirmation of the consequent)

If p then q. q. Therefore p.

["If I go to the mall I always buy a toy. I bought a toy. Therefore I
went to the mall."]

3. The Fallacy of Argument from Authority: Believing something is true
only because some particular person said so. [This is a fallacy because,
first, everyone can be wrong and, second, because one person's belief is
insufficient evidence to establish truth.]

4. The Fallacy of Equivocation: A word or phrase is used in one sense in
one premise and in another sense in another needed premise or in the
conclusion.

["The loss of his money made Jones mad {=angry}; mad {=insane} people
should be institutionalized; therefore Jones should be
institutionalized."]

Note -- I see the fallacy of equivocation over and over in this list!
That's probably why there are so many posts having to do with the use of
language.

5. The Fallacy of False Cause ("non causa pro causa") -- most commonly in
the form "post hoc ergo propter hoc" meaning "after which therefore
because of which":

["I lost my job today. I broke a mirror this morning. So, breaking a
mirror causes bad luck."]

6. The Fallacy of Accident: Applying a general rule to a particular case
for which a special circumstance makes the general rule inapplicable.

["People are capable of seeing. Therefore, that blind man can see."]

7. The Converse Fallacy of Accident: Arguing improperly from a special
case to a general rule.

["I took _____ {fill in the blank with your favorite health food store
dietary supplement} and my sore shoulder isn't sore any more. Therefore,
you ought to pay $100 a month to buy _____ and it will fix your sore
shoulder, too."]

I think that's probably enough for now, but there are many others
including the argument "ad hominem" [speaking "against the person" rather
than to the issue], "ad populum" [appealing to popular attitudes rather
than to logical reasons], "petitio principii" ["begging the question" or
presuming the conclusion, either overtly or covertly, in the premises],
etc.

The point is, when people present ideas fallaciously we should be
skeptical about their conclusions. That's not to say that their
conclusions are necessarily false; it is only to say that we have no more
reason for believing the conclusions to be true after we read the
statement than we did before we read it.

And just to ward off those who (illogically, in my opinion) want to claim
that they are immune to being rational -- it's not necessary for them to
accept "my" ideas of logic -- I respond thusly:

If you use the forms of logical argument in support of your ideas and
conclusions (i.e., to try to convince me to believe something), then I
must apply the rules of logic in assessing your argument. You cannot have
your cake (use logical forms to supply force for your argument) and eat it
too (deny me the use of logical rules in assessing it.)

-- 

"John Gunkler" <jgunkler@sprintmail.com>

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