This document discusses deductive and inductive reasoning. It provides examples of arguments using each type of reasoning and asks the reader to determine the reasoning used. Deductive reasoning uses general statements or rules to derive a specific conclusion, working from general to specific. Inductive reasoning draws general conclusions from specific observations, working from specific to general. The document also notes that deductive reasoning conclusions can be invalid if the premises are incorrect or the reasoning is not applied properly.

1. Have you ever tried
convincing someone
using facts or
definitions?

2. Every human is mortal. Socrates is
a human.
Therefore, Socrates is mortal.

3. All appliances use electricity.
Rice cooker is an appliance.
Therefore, rice cooker uses
electricity.

4. DEDUCTIVE REASONING
uses facts, rules, definitions,
or properties to reach logical
conclusions.

5. Inductive Reasoning – from specific
(examples) to general
Deductive Reasoning – from general to
specific

6. Inductive Reasoning
from specifics to general
Deductive Reasoning
from general to specific
Examples
Michelle, Krisna, and Karen
All dancers are thin. Karen is
are all thin. They are dancers. a dancer. Therefore, Karen is
Therefore, all dancers are
thin.
thin.
Ms. Mayumi, Mrs. Marikit, and
Mr. Mabini are teachers. They
are all nice. Therefore, all
teachers are nice.
All teachers are nice. Ms.
Mayumi is a teacher.
Therefore, Ms. Mayumi is
nice.
Parrots, eagles, and doves
are birds. They can all fly.
Therefore, all birds can fly.
All birds can fly. Parrot is a
bird. Therefore, parrots can
fly.

7. Determine whether each argument uses inductive
or deductive reasoning.
1.All mammals have kidneys. Dogs are mammals.
Therefore all dogs have kidneys.
2.All swans we have seen have been white;
therefore the next swan we see will be white.
3.All even numbers are divisible by 2. 6 is an even
number. Therefore 6 is divisible by 2.
4.5 is odd and not divisible by 2. Therefore all odd
numbers are not divisible by 2.

8. Conclusions made by deductive reasoning
can be faulty/wrong/invalid when…
1.the premises are incorrect.
2.deductive reasoning is not executed
properly.

9. 1. …when the premises are
incorrect or not valid.
Example:
All even numbers are divisible by 4.
6 is an even number.
Therefore 6 is divisible by 4.

10. Michael Jackson was not shot by a lunatic.
Princess Diana was not shot by a lunatic.
Therefore, John Lennon was shot by a
lunatic.

11. 2. …deductive reasoning is not
executed properly.
Example:
All the people in that certain room are
bakers.
Jim is a baker.
Therefore, Jim is in that room.

12. All cats chase mice.
My pet Whitey chased a mice.
Therefore, Whitey is a cat.

13. Prepared by Ms. Mariele D. Brutas
Ateneo de Naga University High School