AinA 080 – Introduction to formal fallacies.

We noted that the form of an argument is its underlying structure and this underlying structure can be represented by letters or symbols. So if you have the argument:

the ps and qs can be thought of as containers into which you can pour any content although that content has to be a statement, e.g.

if [I am hungry] then [I will buy myself some food]
if [it is sunny] then [I will play outdoors]
etc.

The important thing is that wherever in the argument there is a container with the same label it contains the same content,

if [it is sunny] then [I will play outdoors]
[it is sunny]
[I will play outdoors]

Obviously if a p or a q is used in a different argument it can have different content just as xs and ys in maths will have different content in different equations.

Although informal logic is less interested in reducing arguments in this way, there are a couple of things in our course for which it is helpful.

The course requires you to be able to make a distinction between formal and informal fallacies.

Fallacy is another one of those words that is sometimes used in slightly different ways but you can say

A fallacy is a common error in reasoning.

When people try to reason things out they make mistakes. Some of these mistakes are so common that they have been given names. Two of these fallacies relate to the structure of the argument and that is why they are called formal fallacies, i.e. they are concerned with the underlying form of the argument rather than with the content of the argument.

Essentially, they are arguments that have a structure which people frequently mistake for being valid when, in fact, they are invalid.