Discerning the structure of an argument is only the first step in assessing arguments. Students must also learn to critically evaluate arguments. That means asking whether the premises really do support the conclusions. It also means asking whether or not the premises themselves are true. It’s the first part that is the hardest thing for most students. We are all accustomed (to varying degrees) to questioning the truth of someone’s claims. What we do not often ask is whether someone’s conclusion really does follow from his/her premises.

Mastering the art of picking out premises and conclusions is the first step toward good analytical thinking, but we must also think about whether the premises really do support their conclusions. Making that sort of determination requires that we think a little bit about the different kinds of arguments. There are several ways of categorizing arguments, but for our purposes, we can distinguish all arguments into one of two types: deductive and inductive.

Deductive argument: an argument whose premises make its conclusion certain
Inductive argument: an argument whose premises make its conclusion likely
(Note: Some dictionaries – and even some older logic texts – define deductive arguments as arguments that reason from the general to the specific and inductive arguments as those that reason from the specific to the general. That particular usage of the terms is obsolete.)

The difference between deductive and inductive arguments is easiest to see by way of examples.

This is an instance of a deductive argument. We can tell that the argument is deductive because the two premises (that is, the first two sentences) guarantee the truth of the conclusion. If the two premises really are true, then there is no possible way that the conclusion could be false. Here’s another example:

Again, this is a deductive argument, for the truth of the premises guarantees the truth of the conclusion. Contrast those examples with this one:

This argument is inductive. The premises make the conclusion likely, but they do not guarantee that the conclusion is true.


Now, write your own thesis statement:

  1. What is your TOPIC?

  2. How are you going to discuss it in your essay?  (FACT, VALUE or POLICY).

  3. What is the premise of your argument?

  4. What category is your argument in INDUCTIVE or DEDUCTIVE?

  5. Why is this important?  (ETHOS, PATHOS, or LOGOS)