2 basic types of reasoning l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
2 Basic Types of Reasoning PowerPoint Presentation
Download Presentation
2 Basic Types of Reasoning

Loading in 2 Seconds...

play fullscreen
1 / 12

2 Basic Types of Reasoning - PowerPoint PPT Presentation


  • 251 Views
  • Uploaded on

2 Basic Types of Reasoning. Deductive Inductive. Deductive Reasoning. Attempts to provide sufficient (or conclusive) evidence for the conclusion Deductive reasoning can be recognized by the structure of the argument and sometimes by the conclusion offered. Inductive Reasoning.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about '2 Basic Types of Reasoning' - Mercy


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
2 basic types of reasoning
2 Basic Types of Reasoning
  • Deductive
  • Inductive
deductive reasoning
Deductive Reasoning
  • Attempts to provide sufficient (or conclusive) evidence for the conclusion
  • Deductive reasoning can be recognized by the structure of the argument and sometimes by the conclusion offered
inductive reasoning
Inductive Reasoning
  • Attempts to make the conclusion probable or likely—evidence is not intended to be conclusive
  • Typically recognized by probabilistic claims in either or both of the premises and conclusions
  • Includes statistical and demographic reasoning, predictions, analogies and explanations
some examples
Some Examples
  • Either Bob or Joe was going to win the award. Bob didn’t win, so Joe must have.
  • I think Wayne committed the murder. He had the motive, he had the opportunity, his bloody glove was found on the scene, and he has no alibi.
  • I’m sure Alice knows how to swim. After all, most people know how to swim.
more examples
More Examples
  • If you stop smoking, you’ll live longer. Current research shows that on average, non-smokers live 5.5 years longer than smokers.
  • If we elect another Republican in 2008, the debt will just get worse. The last three Republican presidents we elected all sent the debt sky-high.
  • Since 2 x 2=4, and 22 is the same as 2 x 2, then 22=4.
judging validity
Judging Validity
  • A deductive argument is judged on 2 criteria: validity and soundness
  • An argument is valid if the truth of the premises would guarantee the truth of the conclusion
  • An argument is invalid if the conclusion could be false even if all the premises are true
  • N.B.: This judgment is purely formal—it has nothing to do with the truth of either premises or conclusions
some examples7
Some Examples
  • Either the kitchen is on fire, or my pot roast is burning. I can see the kitchen’s not on fire, so my pot roast must be burning.
  • All CEOs are wealthy. Martin is wealthy, so he must be a CEO.
  • Only Democrats would vote for Hilary Clinton. Wade is a Democrat, so he must have voted for Hilary.
more examples8
More Examples
  • Deceptive advertising is no different from lying. Since lying is wrong, so too is deceptive advertising.
  • Republicans support tax cuts for the wealthy. George is a Republican, so he must support tax cuts for the wealthy.
  • Republicans support tax cuts for the wealthy. John supports tax cuts for the wealthy, so he must be a Republican.
argument forms
Argument Forms

There are some argument form that are always valid

They are: Modus Ponens, Modus Tollens, Categorical Syllogism, Disjunctive Syllogism, Hypothetical Syllogism and Constructive Dilemma

argument forms continued
Argument Forms Continued

There are two argument structures that are always invalid.

They are: Affirming the Consequent and Denying the Antecedent

soundness and unsoundness
Soundness and Unsoundness
  • A deductive argument is sound is (1) it is valid, and (2) its premises are true.
  • A deductive argument is unsound if either (1) it is invalid, or (2) it is valid, but at least one premise is false
some examples12
Some Examples
  • All men are mortal. Socrates is a man, therefore Socrates is mortal.
  • Either the moon is made or green cheese, or I’m the Pope. Unfortunately, the moon IS made of green cheese, so I’m sadly not the Pope.
  • If George Bush was re-elected, our economic depression was sure to continue. Our economic depression continued, so Bush was re-elected.
  • Only rock stars and athletes are wealthy. Since Ellen is pretty wealthy, she must be either a rock star or an athlete.