Inductive vs. DeductiveReasoning
Descriptions and examples
Types of Reasoning
• Deductive reasoning goes from general to specific
• Inductive reasoning goes from specific to general
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Deductive Reasoning
• Deductive reasoning starts with a premise, which we accept to be true. Then, from that rule, we make a conclusion about something specific.
• Example:• All turtles have shells• The animal I have captured is a turtle• I conclude that the animal in my bag
has a shell
Deductive Reasoning
• A conclusion reached with deductive reasoning is logically sound, and airtight, assuming the premise is true.
• If a penny is a flat disc, copper in color and has a profile of Honest Abe on it, then I can be sure the penny in my pocket has those qualities.
Deductive Reasoning
• The strength of deductive reasoning is that conclusions derived with it are fully certain.
• The weakness, which was illustrated in the most recent example, is that no new information is added.
• The fact that the penny in my pocket is a copper disc with Lincoln on it was clear from the initial data, so the conclusion hasn't added any new information.
Inductive Reasoning
• Inductive reasoning is making a conclusion based on a set of experiences or data. If I observe that something is true many times, concluding that it will be true in all instances is a use of inductive reasoning.
• Example:• All sheep that I've seen are white• All sheep must be white
Inductive Reasoning
• The strength of inductive reasoning is that new information came be stated.
• The weakness is that the new information cannot be proven.
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Deductive Reasoning
• All dogs are mammals and mammals have kidneys.
• Therefore your dog has kidneys.
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Deductive Reasoning
• All squares are rectangles, and all rectangles have four sides.
• All squares have four sides.
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Deductive Reasoning
• All chemists are smart if chemists are scientists and all scientists are smart.
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Inductive Reasoning
• All swans we have seen have been white; therefore all swans are white.
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Inductive Reasoning
• All swans we have seen have been white; therefore the next swan we see will be white.
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Inductive Reasoning
• All known planets travel about the sun in ellipitical orbits; therefore all planets travel about the sun in ellipitical orbits.
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Deductive or Inductive?
• Since all men are mortal, and Socrates is a man, Socrates is mortal.
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DEDUCTIVE
Deductive or Inductive?
• Exploration of the surface of Mars has produced some surprising facts. Therefore exploration of the surface of Jupiter will produce some surprising facts.
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INDUCTIVE
Deductive or Inductive?
• Since Chris is a good athlete, Chris's sister must be a good athlete also.
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INDUCTIVE
Deductive or Inductive?
• The sun is a star; the sun has planets; therefore some stars have planets. QuickTime™ and a
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DEDUCTIVE