Whether you are preparing to convince your friends that a holiday to the mountains is the best way to spend the spring break or you are writing for your term finals and are debating if global warming is a political issue, constructing a good argument will increase your chances of being more persuasive.

But what is a good argument?

To be able to figure that out, we first need to understand the difference between inductive and deductive arguments.

Deductive Vs Inductive Arguments

Deductive Argument

A deductive argument is a category of logical argument where the premises are definitively proving the truth of the conclusion.

Example:

All mammals possess brains. (Premise A)

My guinea pig is a mammal. (Premise B)

Premise A + Premise B = Conclusion C

My guinea pig has a brain. (Conclusion C)

The conclusion that my guinea pig has a brain is beyond doubt.

Inductive Argument

By contrast, an inductive argument is a type of logical argument where the truth of the premises provide good reasons to believe that the conclusion is probably true.

Example:

Most of the winds come from the north. (Premise A)

It’s getting windy. (Premise B)

Premise A + Premise B> Conclusion C

This wind must come from the north. (Conclusion C)

Note the difference between the two: in deductive reasoning we can be 100% sure that the conclusion is true based on the premises, while in inductive reasoning, there is a degree of probability that the conclusion is true following from the premises. But it could also be false.

In the example above, premise A states that most winds come from the north, not all winds. Thus we cannot conclude with certainty in this example that the current wind comes from the north. It’s only probable.

You likely can already tell that deductive arguments are not extremely useful in everyday debates. While these are fantastic for science or logic, a lot of the everyday life issues and discussions cannot be proven with certainty. People need to use argumentation in order to present their claims to others, as a day to day activity which has to do with social interaction or persuasion of peers. By contrast, scientists use arguments to discover new ideas, so deductive argumentation in their case is paramount. Whereas the argumentation necessary for persuasion on topics which cannot be proven with certainty relies heavily on inductive reasoning.

Inductive reasoning is also known as informal logic.

Critical Thinking and Informal Logic

So what is the relation between critical thinking and informal logic? And what is informal logic for that matter?

Informal logic acknowledges that arguments occur in everyday communication and might not follow the strict rules imposed by deductive logic, while formal deductive logic looks at argument as a set of statements which are held together by strict rules.

Leaving formal, deductive logic aside, as it doesn’t constitute the object of our study, the concepts of critical thinking and informal logic do overlap in several areas.

While a few domains are considered tangential or sometimes overlapping with critical thinking and with informal logic, such as rhetoric, dialectics, dialogue theory or fallacy theory, it is argumentation the one that shares with critical thinking the focus on argument evaluation and their cogency.

Enter Stephen Toulmin- the British philosopher and educator who developed one of the most significant contribution to how we analyse arguments which occur in natural language. He developed a model for analysing arguments which is used successfully in teaching students how to write argumentative essays, while applying critical thinking at the same time.

Toulmin Method for Good Arguments

Toulmin argued for a model of reliable arguments: for an argument to be considered good, it has to be formed of six components, divided in two groups.

The first group of components are:

Data: The evidence, information, events or even artistic proofs (see the article on how to influence people by using artistic proof) which support the truth of the argument. The argument without data does not have a real value.

Claim: The conclusion of the argument, although, the claim is not necessarily the final conclusion of the argument, in fact it can represent an intermediate step used as data for the next inference.

Warrants: The reasons that help move the argument from the data to the claim. Many times the warrants are general and implicit and as Toulmin points out, they help answer the question ‘How do you get there?’

The second group of components contains:

Backing: Statements that serve as evidence for showing that the warrants are true.

Rebuttals: Exceptions to the claim, showing circumstances when the claim might not be true.

Qualifiers: Statements or phrases which reflect the level of probability or truth of the claim.

Toulmin in Practice

Let’s see an example of argument represented through Toulmin’s diagram:

I am arguing that Coronavirus lockdown might determine a spike in the number of divorces (Claim).

The word ‘might’ used in the claim suggests a moderate degree of probability (Qualifier).

To support my claim, I use varied data such as the idea that financial burdens might increase arguments or that couples might find it difficult to communicate openly (Data).

Two elements constitute the Warrants: the fact that money fights predict divorce rates, but also that arguments and domestic violence were reported as causes for breakdown of marriages (Warrants).

To back the warrants, I include the links of the studies which show evidence for these claims (Backing). I also consider the counter arguments, such as that couples good at communicating, split their responsibilities equally and collaborate together for the best outcome might see this test as strengthening for their relationship (Rebuttal). Including rebuttals in your argument is always a good idea, because it gives you the opportunity to analyse the weaknesses of your claim and also predict the counter-arguments that the other party might bring to the table.