Faulty Thinking #1

I have become very interested in logical fallacies and I have been searching the Internet for examples. Here is a list of the most important errors we make when we argue:


The Slippery Slope This is a series of statements that have a superficial connection with one another, and which lead into what is usually a rather far-fetched a conclusion.


If we pass laws against fully automatic weapons, then it won’t be long before we pass laws on all weapons, and then we will begin to restrict other rights, and finally we will end up living in a communist state. Thus, we should not ban fully automatic weapons.

If we legalize marijuana, the next thing you know we’ll legalize heroin, LSD, and crack cocaine

The notion of a single exam implies there are national standards, and that implies a national curriculum. Then we are on the way to a centralized Prussian education system


Appeal to Tradition X has always been done. Therefore X is right.

Claim something to be well established and proven. Say that it is traditional, and that to change it would be sacrilegious in some way.


My father and his father before him polished wood this way. Don’t tell me how to polish wood.

The tradition in this town is to buy from local traders.

Sure I believe in God. People have believed in God for thousands of years so it seems clear that God must exist. After all, why else would the belief last so long?

Canada has always defined marriage as between one man and one woman, so we shouldn’t change it.


Attacking the Person (argumentum ad hominem) The person presenting an argument is attacked instead of the argument itself. This takes many forms. Here I am going to focus on three major:

  1. ad hominem (abusive): instead of attacking an assertion, the argument attacks the person who made the assertion.
  2. ad hominem (circumstantial): instead of attacking an assertion the author points to the relationship between the person making the assertion and the person’s circumstances.
  3. ad hominem (tu quoque = you too): this form of attack on the person notes that a person does not practise what he



Only an idiot would believe in God! (ad hominem abusive)

We should discount what Premier Klein says about taxation because he won’t be hurt by the increase. (ad hominem circumstantial)

Bill claims that tax breaks for corporations increases development. Of course, Bill is the CEO of a corporation. (ad hominem circumstantial)

I think that we should reject what Father Jones has to say about the ethical issues of abortion because he is a Catholic priest. After all, Father Jones is required to hold such views.  (ad hominem circumstantial)

You say I shouldn’t drink, but you haven’t been sober for more than a year. (ad hominem tu quoque)

You are wearing a leather jacket and you have a roast beef sandwich in your hand! How can you say that using animals for food and clothing is wrong. (ad hominem tu quoque)


Argument from Ignorance (argumentum ad ignorantium) Nothing is known about A. Yet a conclusion is drawn about A. Facts may be give all around a particular area, yet nothing specific is said about the area. Based on this circumstantial evidence, it is assumed that something may be known about A. A variant is where there lack of evidence is assumed to be proof, for example when a murder suspect does not have an alibi.


Since you cannot prove that ghosts do not exist, they must exist.

Senator Joe McCarthy: …do not have much information on [case 40] except the general statement of the agency…that there is nothing in the files to disprove his Communist connections


False Dilemma: Two choices are given when in fact there are more options.


George Bush: You are either you’re for or against America.

Barack Obama: America has a choice: to back my recovery plan, or return to the bad old ways that led to disaster.


More to come….



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