Logical Fallacies: argumentum ad hominem

(Updated 2/22/2017)

What is a Logical Fallacy?

…..Literally, a reasoning mistake

…..Example:

. . . . .You say 1+1=2

. . . . .Someone wishes to argue otherwise

. . . . .They say you flunked arithmetic in 3rd grade

. . . . .People start to doubt that 1+1=2!

. . . . .This is crazy, right?

. . . . .It happens all the time…

. . . . . . . just not as obviously

. . . . .Example:

. . . . . . .Someone suggested a warning sign

…that some chemical additive might be hazardous

…based on experiments giving it to animals

. . . . . . .Ad hominem response related to hypothetical poor animal experiment design

. . . . . . .Result:

No response

Discussion ended

…and … no warning sign!

. . . . . . .This was a highly effective (ab)use of ad hominem argumentation

. . . . . . .(so why didn’t I/someone point this out?)

…..Politicians do it a lot

. . . . . . Some use it more than others

…..Roman politicians were experts!

…..People fall for it frequently

…..This one’s called the ad hominem argument

…..Latin for to the man

…..The Romans taught oratory in school

. . . . .How to use logical fallacies
. . . . .to manipulate public opinion
. . . . .was part of their education!

. . . . .That’s why many have Latin names


Ad hominem arguments

  • Just one of many logical fallacies
    • …..There are dozens
  • Argumentum ad hominem is one of the most important
    • …..Ad hominem arguments are particularly common
    • …..There’s an entire wikipedia entry on them

Example
(from an email exchange
whose only real value was in
providing an example for you folks!):


[stuff deleted about climate change]

ML: Anybody who claims otherwise is ignorant, uninformed, or lying.

PD: Ooh – is this the choose-your-own-ad-hominem part of the show?  Can I play too?

[more stuff deleted]

Example 2:
A student (Sp 2017) cited a debate between Bill Nye and Ken Ham as containing interesting examples of ad hominem statements (warning: it’s long)


  • There are various subtypes
    • …..Example:
      • . . . . .ad feminam
  • Let’s look at some
    • …..types
    • …..examples

Abusive ad hominem

Argue against something by
attacking the person arguing for it

. . .in contrast to arguing against the thing itself

…..John Nash’s mathematics
…..can’t be Nobel prize-worthy
…..because he is schizophrenic

. . . . .logical fallacy?

…..Amy Winehouse’s music sucks
…..because she’s in the “27 club”

. . . . .logical fallacy?

…..Jimi Hendrix’s music is great
…..because he’s in the “27 club”

. . . . .logical fallacy?

…..We shouldn’t do the project like Irving suggests
…..because he’s totally uncool

. . . . .logical fallacy?


Tu toque ad hominem

tu toque = “you also” in Latin

Example:

…..A parent says, don’t smoke, it’s unhealthy

…..The kid says, “but you smoke”

. . . . .“Practice what you preach!”

. . . . .“So I don’t believe you!”

children
. . . . . . . .  so there, pops! (Photo found at http://uhaweb.hartford.edu/KRAKYTA)

…..is there a logical fallacy there?

Politics is full of examples:

…..politician x argues for “family values”

. . . . .but is found to be having an affair

. . . . .does that mean “family values” are bad?

. . . . .what does it mean?

. . . . .Is the term “family values”
itself an ad hominem attack?

. . . . . . .It cleverly says
“The other guys do *not* have family values”
without actually saying so

…..politician y argues against gay rights

. . . . .but is caught soliciting in an airport bathroom

…..Al Gore’s house was once found to be energy-inefficient

. . . . .Is that an argument against the
existence of global warming?

. . . . .Is it an argument
against reducing CO2 output?

…..”Politician z‘s argument is wrong,
s/he’s a Democrat/Republican/whatever”

…..what about,

. . . . .”Take politician a’s argument with a grain of salt, s/he took campaign money from the ___ industry”

. . . . .logical fallacy?

. . . . .”Politician a’s argument is wrong,
s/he took campaign money from the ___ industry”

. . . . .logical fallacy?

Summary:

. . . “ad hominem” means “to the man”

. . . it doesn’t mean “invalid” or “valid”

. . . often it is an invalid/sneaky/sleazy argument trick

. . . . . . ethical?

. . . sometimes it is logically reasonable


The ad feminam argument

literally, “to the woman”

Example:

  • …..Comedian Caroline Picard is a big football fan
  • …..Suppose a woman critiques a team
    • …..A fan doesn’t like the comment
    • …..response 1:

. . . . . .argue it on technical merits

  • …..response 2:

. . . . .dispute it by saying,

“that’s crazy – women don’t know football”

. . . . .that’s an “ad feminam” argument!

. . . . .what is the logical flaw?

. . . . .is it ethical?


More on ad feminam arguments

What if the argument is:

….she does not know football,
so her argument is wrong

. . . . .logical fallacy?

…..she does not know football,
so her argument is less believable

. . . . .logical fallacy?

…..she plays women’s football on weekends,
so her argument is right

. . . . .logical fallacy?

…..she plays women’s football on weekends,
so her argument is more believable

. . . . .logical fallacy?


Circumstantial ad hominem argument

Saying that
the arguer is biased,
therefore
the argument is invalid

subtype: conflicts of interest

“That’s just PR spin;
they’re paid to say that”

. . . . .is that argument “to the man”?

. . . . .is it logically fallacious?

The American legal system

based on paying people to argue one side

it’s “adversarial”

Other countries have different approaches

Does the adversarial approach affect believability of the argument?

Can you think of a better method?


Guilt by association

(This example is not as current as it used to be but it illustrates the idea nicely):

“You want to get out of Iraq?
Well, Iran wants us to do that, too!”

…..“So we should not reduce troops”

. . . . .logical fallacy?

…..“So your argument is traitorous”

. . . . .logical fallacy?

…..“So your argument is wrong”

. . . . .logical fallacy?

Ok, help me out!
We need a more recent example.
Doesn’t have to be about foreign affairs.

Groucho Marx:
“I’d never want to be in a club
that would have me as a member.”


Other kinds of logical fallacies

red herring arguments

slippery slope arguments

Testimonial about this lecture

        (From student in this class from a previous semester)

         “After this discussion, I have come to realize that my husband uses these tactics in our arguments.  Thank you for opening my eyes to something that has driven me crazy for years.

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