4 Types of arguments
To write a text or participate in a debate, whether formal or informal, it is important to know some types of valid arguments that can be used to justify your opinion. In the list below, we present four of these types of arguments, illustrated with a series of examples to facilitate understanding and use of this information.
Argument from authority
This type of argument consists of citing an authority on a given subject to justify an opinion. This authority can be a renowned research institution, a researcher known in his field, a great scientist, a philosopher etc.
If the government does not use the police to guarantee security, crime will take over the city, because, according to Hobbes, if the man is left at ease, there will be a “war of all against all”.
In this argument, to justify the conclusion that crime will take over the city if the government does not use politics, the author cited a statement by Thomas Hobbes, a 17th century philosopher who can be considered an authority on the subject of violence.
This is an argument that draws a general conclusion from particular facts. It is also called, in some contexts, an example argument.
Corruption is a widespread problem in Brazil, and not just in politics. We can see this through a large number of examples. Think of the people who skip the supermarket line, who evade income taxes, the guard who drinks coffee at the bakery for free in exchange for special protection for the establishment, the student who checks at work to save money. In Brazil, corruption is definitely widespread.
In this argument, the conclusion that corruption is widespread in Brazil was based on the enumeration of examples, particular facts, that show this.
Argument from analogy
Arguments from analogy use the comparison between two similar things to draw a conclusion. The assumption of this argument is that similar things behave in similar ways or should be treated in the same way.
Examples of this type of argument are abundant. Below we list some of them.
Nobody would let anyone fly an airplane, as this requires specialized knowledge. Now, governing a country also requires specialized knowledge, so it should be prohibited for people who have no knowledge to govern a country in any way.
A drug tested on rats to cure cancer has given good results. Therefore, if used on humans, it will probably also bring good results.
In both cases, the conclusion was drawn based on a comparison between two similar things. In the first, a comparison is made between flying an airplane and governing a country; in the second, between rats and humans.
The deductive argument is a favorite of philosophers, because it leads to an unquestionable kind of conclusion. If the argument were a fight, the deductive argument would be considered the fatal blow. A deductive argument is one that, if the premises are true, the conclusion will also be necessarily true.
(P1) The decrease in infant mortality rates only occurs with time, coordinated work and planning. Now, (P2) the infant mortality rate of São Caetano do Sul, in São Paulo, was the one that fell the most in the country. (C) Therefore, São Caetano do Sul was the municipality in Brazil that invested the most time, coordinated work and planning in the area.
The above reasoning is a valid deductive argument, because the (C) conclusion is true, if the premises (P1 and P2 ) are true. The only way to question this type of argument is to show that the premises on which it is based are false.
Invalid argument types
The misuse of any of these types of arguments can make you commit a fallacy. Fallacies are arguments that seem valid but are not. This is a serious flaw in the argument that must be avoided.
So, when using an authority argument, be careful not to commit the fallacy of the appeal to irrelevant authority; when using an inductive argument, be careful not to make a hasty generalization ; when using an argument by analogy, be careful not to make a false analogy ; finally, when using a deductive argument, be careful not to commit a formal fallacy.
Walton, Douglas. Informal Logic: A Pragmatic Approach. Cambridge: Cambridge University Press, 2008.