Fallacies
An argument is meant to try and convince people that a certain belief or point of view should be
accepted. Critical thinkers have noticed that quite often people, when presenting their persuasive
argument, introduce certain persuasive techniques in the form of a statement (a premise) which are
actually misleading mistakes in reasoning. The premise containing the mistake therefore cannot be
accepted as necessarily true, and as a result renders the argument unsound. These common mistakes in
reasoning are called fallacies. When evaluating an argument you need to be able to spot if a fallacy is
being used.
There are two types
1. Informal Fallacies
2. Formal Fallacies
Some common Informal fallacies
1.The false dilemma
This fallacy occurs when a premise in an argument presents you with two things to choose from, as
if there were only two, when in fact there are actually more than two choices available. This is what
makes this a mistake in reasoning.
Example 1
Immigration must be stopped. Either we block people coming into this country or we raise taxation to
pay for benefits. What’s it to be?
Example 2
Everyone wants to get the best return for their investment. Put your money into this bank or throw
your money down the drain.
2.The slippery slope
This fallacy occurs when a premise in an argument states that if we take a certain action then this will
inevitably lead to further undesirable consequences. To make this kind of claim is unjustified. It is
therefore a mistake in reasoning.
Example 1
You must never start smoking. If you start smoking, before you know it you will be taking other hard
drugs. Do you want to end up a junky?
Example 2
The legal age for drinking should not be lowered. If we go down this route then it wont be long before
the legal age for getting married will be reduced as well.
3.Attacking the person
This fallacy occurs when in order to get a point across, a premise in an argument is used to attack the
person who you do not agree with rather than their argument
Example 1
The war in Iraq was a mistake. The decision to go to war was made by George W. Bush who is a bumbling
idiot who is as thick as two short planks.
Example 2
You can’t accept what he says in the witness box. Everyone knows he’s a liar a scoundrel and a rogue.
4.Appeals to illegitimate authority
This mistake in reasoning occurs when the conclusion of an argument is supported by a statement that
appeals to some questionable source of authority.
Example 1
If a bully hits you then you should hit them back. That’s what you should do because my dad says so.
Example 2
Our society is becoming more violent. If you don’t believe me ask my next door neighbour who was
mugged last week
5.Appeals to ignorance
This mistake in reasoning works by assuming that if there is no evidence against the truth of a
statement then the statement can be accepted as true.
Example 1
I believe there is extra terrestrial life somewhere in our vast universe. After all there is no evidence
to the contrary
Example 2
Example 2
God exists. You can’t prove me wrong.
6.The circular argument
This is the mistake in reasoning that involves assuming in a premise, the statement you’re trying to support
with the premise. This fallacy occurs when either the same statement is used in a premise and the
conclusion in an argument, or when one of the premises could not be known to be true, unless the conclusion
were first assumed to be true
Example 1
Only an untrustworthy person would be a politician
The fact that all politicians are untrustworthy is proof of
this
Example 2
David:
Anna:
David:
Look, women shouldn’t become soldiers.
Why not?
Because it is a job for a man
Example 3
P1 The Bible says that God exists
P1 The Bible is the Word of God
Therefore God exists
7 The mistake which states or implies that one thing causes another when it cannot be shown to
This is the mistake in reasoning that states there is a causal link between things, without
good reason.
Example 1
Example 2
Most ‘hard’ drug users start off as ‘soft’ drug users.
The rise in violence in our country is linked to the rise in inner city poverty
8. An appeal to irrelevant consequences
This is the mistake in reasoning in which a statement (a conclusion) is supported by a premise that
either appeals to the good consequences that result from accepting it, or the bad consequences that
result from not accepting it.
Example 1 God must exist. The reason being that if he does not then we are all deluded.
Example 2 Everyone should give money to Children in need, because it greatly helps under privileged
children
Fallacies
Mistakes in reasoning which make an argument unsound
1.
The false dilemma which only suggest two or more choices
2.
The slippery slop where will it all end if you accept a particular idea
3. Attacking the person instead of the argument
4. Appealing to an illegitimate authority to support your argument
5. Appealing to ignorance for support of a premise
6. Circular argument in which the conclusion is assumed in the premises
7. Saying or implying that one thing causes another
8. Unjustified or illegitimate appeals to authority
9. An appeal to irrelevant consequences
Formal fallacies
Formal fallacies relate to the structure of the argument. and make an argument invalid
Example 1
When the rule about conditional statements is broken a formal fallacy has been
committed. (check out this rule)
Example 2 The circular argument can also be said to be a formal fallacy.