Lesson 1: What is an argument?

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This is the first lesson of “Philosophy and critical thinking” course, but firstly, we will not jump into explaining what the concepts like “critical thinking” or “philosophy” mean but what an argument is.

The cogency

In philosophy, arguments are like blood in the body, they help the beliefs live. But only good arguments can make true beliefs. In the below example, you will see the difference between argument and personal assessment.


Tom & Tracy talking to each other:

Tom: Do you know that pigs can fly?

Tracy: No, they can’t fly.

Tom: Why do you know that?

Tracy: I just know that.

Tom: How do you know that?

Tracy: I believe that.

Tom: But why do you believe that pigs can not fly?

Tracy: Because that’s my belief.

Tom: Why do think that your belief can convince me?

Tracy: Because I am right!

Tom: Why do you know that you’re right?

Tracy: I jus think I am right!

Tom: Huh ?????????

If you are sitting next to Tracy and Tom hearing their conversation, you may go crazy! Clearly, their conversation is going to be stuck. Because the fact that Tom has some beliefs, such as a pig can not fly or he’s right doesn’t mean that Tracy also have the same belief. Tracy failed to convince Tom.

Now, let’s try to modify the conversation a little bit:

Tom: Hey Tracy, do you think that pigs can fly?

Tracy: No, pigs can’t fly. I know it for sure.

Tom: Why?

Tray: Because I have a sound argument.

Tom: What argument?

Tracy A thing must have aerodynamics shape to be volant. Pigs don’t have aerodynamics shape, therefore they can’t fly.

Tom: That’s a good argument.

The cogency of an argument makes it logical, leading to higher possibility to convince others. Philosophers always care about cogency and use it to justify any argument. In the modified version of the conversation between Tom and Tracy, Tracy’s conclusion about relationship between aerodynamics shape and the ability to fly may not exactly true, but at least he spent less effort to convince Tom.

What is an argument?

An argument is connected beliefs. The structure of argument is very important because it helps to generate new knowledge from existing ones. The popular form of an argument is very simple, but powerful:

P + P ===> C 

P is called premise, they are beliefs that the authors of the argument think to be true.

C is called conclusion, is the new belief after joining premises. 

===> is called referring, is the process of being from premises to conclusion. 

Below is some examples of arguments:

Ex 1: All men eventually die. Socrates is man. Therefore, Socrates will die.

Ex 2: All birds can fly. Chicken is a kind of bird. So, chicken flesh is very delicious.

Ex 3: All young men desire to be successful. I am young, therefore I also desire to be successful.

Ex 4: Every animals with four legs eat grass. Tigers have four legs. So, tigers eat grass.

Ex 5: Thomas is not faithful. Because he is a man, every men are not faithful.

Valid and sound argument

We have 5 above examples of argument. But how do we assess these arguments? There are 2 ways:

#1: Assessment based on the truth of the premises. In ex2 and ex4, not every birds can fly, dogs and cats also have 4 legs but the don’t eat grass.

#2: Assessment based on the logicalness between premises and conclusion. An argument is logical when if all the premises are true then the conclusion can not be false. Considering ex2, suppose that All birds can fly and Chicken is a kind of bird are true, then the conclusion chicken flesh is very delicious may be still not true because each person have their own flavor.

In general, we have 2 levels to assess an argument:

– A valid argument is an argument that has its conclusion is logically inferred from its premises.

– A sound argument is a valid argument and all its premises are true. 

So ex1, ex3 are sound arguments, ex4 & ex5 are valid arguments and the ex2 is an invalid argument.

That’s quite easy, right?

But let’s step behind and ask yourself: why do you know whether a premise is true or false? Or more clearly, why do you know that all men will eventually die, all birds can fly, all animals with four legs eat grass, all young men desire to be successful…

Or more concisely, what is knowing something? Let’s find the answer in lesson 2.