In this tutorial we will think mostly about relevance and the fallacies that result when irrelevant considerations intrude. Again, there are loads of internet sites describing fallacies. But let's take a quick overview here.
A fallacy is an argument that misleads. It's a "trick" of reasoning. There are two main types of fallacious reasoning: Formal and informal.
These are arguments which are fallacious because of bad form. We've already seen an example of this: the Sanchez case.
Sanchez stays at her banking job only if she gets a raise. So, if she gets a raise, she'll continue at the bank.
This reasoning may at first seem OK. But it's not. To see the problem, notice that the same form of reasoning is obviously wrong in a different context:
There is fire only if there's oxygen. So, if we add oxygen to an area, there will be fire.
But of course this is wrong. Often we have oxygen but no fire: oxygen is a necessary but not sufficient condition for burning.
Notice that both the last two arguments are of this form:
_____ only if _ _ _ _ _. So, if _ _ _ _ _, then ______.
The problem with the argumentation is the form.
Note: Formal fallacies are always or almost always invalid deductive arguments.
Now, the form of this formal fallacy is...
...which of the following are examples of formal fallacies?