Argument Viruses: Logical Fallacies (Ch. 6)
Here we will deal with informal fallacies.
The fallaciousness of relevance, adequacy, or acceptability of the premises, the language used, or
the technique of persuasion, rather than their structure.
Informal fallacies, unlike formal ones, need to be read within a context.
I. Acceptability of the premises.
1. Begging the question (petitio principii): suffers from circularity; the speaker
assumes what she’s trying to prove.
Ex. The belief in God is universal because everybody believes in God.
Ex. It is in every case immoral to lie to someone, even if the lie could save a human life.
Even in extreme circumstances a lie is still a lie.All lies are immoral because the very act
of prevarication in all circumstances is contrary to ethical principles.
Ex. To allow man unbounded freedom of speech must always be, on the whole
advantageous to the state; for it is highly conducive to the interests of the community that
each individual should enjoy a liberty, perfectly unlimited, of expressing his sentiments.
2. Inconsistency. When the argument contains implicitly or explicitly a
contradiction, usually between two premises.
Ex. Members of the jury, there are two compelling reasons why you should find my client
First, the prosecution has failed to prove beyond reasonable doubt that he was anywhere
near the warehouse on the night the theft occurred.
And second, even if he was there, I have presented evidence to show that he was acting
under threats from his companions. In either case, he should be found not guilty.
3. Equivocation. When the premise has two interpretations, one acceptable and one
unacceptable and when the unacceptable is the one present in the conclusion.
Ex. The end of everything is its perfection. The end of life is death. Therefore, death is
the perfection of life.
Ex. Only man is rational. No woman is a man. Therefore, no woman is rational.
Ex. Everyone agrees that a fetus is a human being.All human beings have a right to live.
Therefore, a fetus has a right to live. Ex.Ad for luxurious bedrooms: “Suite Dreams” (suite sounds and makes us think of
4. False dichotomy (bifurcation, false dilemma). It presents us with an “either/or”
situation when in fact there are more than two options to choose from.
The premises present us with alternatives as though they are exhaustive or exclusive
when in fact they are not.
(An exhaustive alternative – covers all possibilities: whether someone is pregnant or not.
Exclusive alternatives – the choice of one excludes the other: a.m. and p.m.)
This way we’re pressured to choose between these two options when in reality there’s a
lot more to choose from, or maybe a choice is not even necessary.
Ex. New Hampshire state motto: Live free or die.
Ex. If you don’t know Bob Dylan, your knowledge of music is inadequate.
Ex.America: Love it or Leave it (written at the U.S. – Mexico border).
Ex. We must legalize drugs. We either legalize them or pay a heavy toll in lives and
taxpayer’s money to continue the war on drugs. And we cannot afford to pay such a high
II. Relevance of the premises.
1.Appeal to pity (argumentum ad misericordiam). Using one’s own tough time or
pointing to someone else’s difficult situation to win the argument.
Ex. Professor, I deserve anAin Critical Thinking. My boyfriend eloped with my cousin
Alice, my parents divorced. My life is a mess. I deserve anAfor my pain.
Ex. Please officer, don’t cite, me for driving under the influence. I know it’s my second
time this year but my parents will put me in a rehab program and my social life will be
Appeal to pity and compassion.
2.Appeal to force (argumentum and baculum).Any type of harassment falls within
Ex. I believe the death penalty to be savage and it has no place in a civilized society.
Well, if you don’t vote in favor of it in the coming election, I’ll tell your parents that you
keep whiskey in your locker. Ex. Barbara, I would like you to come discuss your job promotion with me tonight. Meet
me at the hotel and wear something sexy. Give a little and you’ll get something back.
Note: Keep in mind, though, that there might be cases when the appeal to force might be
relevant; when the speaker is responding to a respective threat or harassment, for
3.Appeal to popularity (argumentum and populem).
Ex. Thousands of students protested the bombing ofAfghanistan. Perhaps you ought to
rethink your support of the administration on this.
Ex. The vast majority of Canadians were against the war in Iraq. How could you support
4.Appeal to authority (argumentum ad vericundiam)
Ex. John Lennon was against the Vietnam War. So, it must have been a big mistake.
Ex. Michael Jordan thinks that Nike makes the best shoes. Buy some today.
Note: There cases when the appeal to authority is relevant. There are two conditions that
allow the use of authority for our arguments:
- 1) We lack the information and experience and we cannot obtain it directly by
ourselves to make a reasonable decision.
- 2) The authority in question is entitled to the status on the matter (e.g., doctors,
5.Appeal to ignorance (argumentum ad ignorantiam)
It occurs when it is argued that something is or isn`t the case simply because you cannot
It goes like that, “if you can`t prove it that I’m wrong than I must be right”.
Ex. Belief in reincarnation is unwarranted; since no one can definitely demonstrate that
the soul can enter another body and come back on Earth.
Ex. It’s clear that God doesn’t exist because science hasn’t proved that he does.
Appeal to ignorance often occurs because we mix types of evidence (e.g., scientific with
philosophical proofs of the existence of God).
6.Appeal to tradition: occurs when we base our arguments only on how things have
been done in the past.
Ex. Of course I’m giving peanut butter to my 6-months old baby, she loves it! Forget about the studies, my mother, grandmother and great-grandmother practically
grew up on peanut butter and they’ve never had any signs of allergies.
7.Ad hominem (attack on the person). It occurs when instead of dealing with the
issue at hand, there is a personal attack or an attempt to discredit someone. The
personal attack aims at a personal characteristic such as age, weight, height, gender,
Ex. The death penalty is savage and has no place in a civilized society. How would you
know you only went to high school!
Ex. Pancho Villa is the best Mexican restaurant in town. Everything I’ve eaten there is
delicious.And they have authentic Mexican sauces. How would you know? You’re
Ex. You can’t take the Canadian Public Safety Minister Vic Towes’Internet surveillance
bill seriously; he’s an adulterer and a liar!
8. Straw man. It occurs when an opponent’s position is presented as so extreme that
it’s indefensible. Then we’re steered towards a more moderate position which
immediately looks a more attractive alternative.
Ex. MP Kennedy is opposed to the military spending bill saying that it’s too costly. Why
does he always want to slash everything to the bane? He wants a pint-size military that
couldn’t fight off a crazed band of terrorists, let alone a rogue nation.
Ex. Those animal rights people make me sick. If they get their way, medical advances in
this country will come to a grinding halt.
Ex. Students these days object to being searched for drugs. If we don’t search them,
they’ll be peddling drugs at school and drug abuse will be rampant.
Straw man and false dichotomy usually go hand-in-hand.
III. Fallacies related to the adequacy of the premises.
1. Hasty generalization fallacy. It occurs when we draw a conclusion about a whole
group based on an adequate sample of the group.
Ex. You should buy a Dell computer. They’re great. I bought one last year, and it has
given me nothing but flawless performance.
Ex. The French