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Logic and Deductive and Inductive Reasoning

Logic is the branch of philosophy involved in reasoning.

Deductive reasoning is the process of reasoning from known facts to conclusions. When you reason deductively, you can say “therefore” with certainty. If your facts were firm to begin with, then your conclusions will also be
firm.
Example
Known Fact: The cut-off date for swim camp registration is June 15. After that date, kids go on a wait list - no exceptions allowed.
Known Fact: You have missed the cut-off to date to register your child by two days.
Conclusion: Your child won’t be registered and her name will go on the wait list.

Inductive reasoning is the process of going from observations to conclusions. This type of conclusion is sometimes called an inference. Successful inductive reasoning depends on the quality of your observations, or evidence.
Example
Observation: Tonya is seen walking from her car to her home with a set of golf clubs.
Observation: Tonya’s husband Jeff loves golf and tomorrow is his birthday.
Conclusion (inference): Tonya has bought the set of golf clubs for Jack.

Can you see the difference? Deductive reasoning drives you to a conclusion based on known facts. Inductive reasoning depends on human observation.Tonya, after all, may be borrowing the golf clubs. Or she may have taken up golf
herself! You wouldn’t know unless you observed carefully, and even then, you would have to describe your conclusion as “probable” but not firm.

This risk of uncertainty in inductive reasoning is why crime scene investigators must ensure that they have gathered many observations (evidence) before drawing a conclusion.

However, here’s something interesting. Once CSI’s have biological evidence of a person at the scene, they can switch back to deductive reasoning. If it is a known fact that someone’s fingerprints or DNA identify him or her, then it can be deduced that fingerprint or DNA evidence at the scene proves the person was there.

So that’s it. Deductive and inductive. It takes both types of reasoning help us move around this world.

Jessica Pegis has been developing learning resources for kids and educators for more than 20 years. She is the author of five books on subjects ranging from citizenship to media literacy. Delving into how kids really learn and understand number concepts eventually inspired her to create Talk PlayThink, a web resource for parents interested in raising thinking kids. Visit Jess's site for more articles on thinking skills and hot thinking topics, as well as fun, brainy stuff to do with your kids..