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1.3 Deduction vs. Induction
1. Inductive Arguments: So far in this course, we have only studied deductive
arguments. These are the sorts of arguments where the conclusion NECESSARILY follows
from the premises. In other words, in a deductive argument, it is IMPOSSIBLE for the
premises to be true and the conclusion false. In this lesson, we will study another kind of
argument: Inductive.
Inductive Argument: An inductive argument is one where the conclusion does not
NECESSARILY follow from the premises, but rather, it PROBABLY follows from the
premises. In other words, it is POSSIBLE that the premises could be true and the
conclusion false. However, this is unlikely to be the case.
There are several varieties of inductive argument. Your textbook lists six. This list should
not be seen as a complete list of entirely distinct categories of argument. Rather, it is
provided merely to give you a wide range of examples of what an inductive argument
can look like. Here are the six examples:
(1) Prediction: When a conclusion follows from our knowledge of the past to a claim
about the future.
Example: “Every time I’ve ever worn these socks, I get shocked when I shut the light
switch. I’m wearing these socks, so I’m probably going to get shocked again.”
The fact that something has happened repeatedly in the past DOES provide us with
evidence for the conclusion that it will happen again—however, we do not know FOR
SURE that it will happen again. At best, we can only say that it will PROBABLY happen
again. So, predictive arguments are inductive.
(2) Analogy: When a conclusion is drawn about something because it is very similar
to something else that you already know about. If you’ve already concluded that
something is true about thing A, and thing B is a lot like thing A in all of the
relevant respects, then it is probably safe to conclude the same thing about B.
Example 1: “My first iphone could play mp3’s. It broke, but I’m buying another one
just like it. I haven’t even looked, but I’m sure that it can play mp3’s too.”
Example 2: “I know for sure that it would be wrong to raise puppies in horrible
conditions where they suffer for their entire lives. But, it is also known that pigs are
just as smart as dogs, and capable of the same wide range of emotions, and feel pain
and suffering in the same way that dogs do. So, it is probably ALSO wrong to raise
pigs in horrible conditions (e.g., the sorts of conditions that exist in factory farms).”
