A Closer Look at Inductive vs. Deductive Reasoning

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A Closer Look at Inductive vs. Deductive Reasoning
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Deductive vs. Inductive Reasoning

• The difference
• inductive reasoning uses patterns to arrive at a
  conclusion (conjecture)
• deductive reasoning uses facts, rules,
  definitions or properties to arrive at a
  conclusion.

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• Inductive reasoning - Think of it like a
• We start with specifics and move to generalities
• Deductive reasoning think of it like a
• We start with generalities and move to specifics.
  

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Examples of Inductive Reasoning

• Some examples
• Every quiz has been easy. Therefore, the test
  will be easy.
• The teacher used PowerPoint in the last few
  classes. Therefore, the teacher will use
  PowerPoint tomorrow.
• Every fall there have been hurricanes in the
  tropics. Therefore, there will be hurricanes in
  the tropics this coming fall.

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Deductive Reasoning
An Example
You are an entering freshman.
Conclusion You will have to take a mathematics
placement test.
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Inductive or Deductive Reasoning?

• Geometry example

What is the measure of angle x?
Triangle sum property - the sum of the angles of
any triangle is always 180 degrees. Therefore,
angle x 30
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Inductive or Deductive Reasoning?

• Geometry example

What is the next shape in the sequence?
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• 90 of humans are right handed. Joe is human,
  therefore Joe is right handed.

DEDUCTIVE
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You are a good student. You get all As Therefore
your friends must get all As too
INDUCTIVE
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All oranges are fruits. All fruits grow on
treesTherefore, all oranges grow on trees
DEDUCTIVE
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• Mikhail hails from Russia and Russians are tall,
  therefore Mikhail is tall

INDUCTIVE
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