What is the difference between deductive and non deductive arguments




















So it necessarily follows that every witch is female. Therefore, any day is a good day to start reading the Bible every day.

The number of chicks in the pen is less than The number of chicks in the pen is more than 6. Certainly, then, the number of chicks in the pen is 8. A good historical case of deductive reasoning goes back to Euclid. Euclid is the author of The Elements, thirteen books collating just about everything the Greeks knew in geometry. The way Euclid proved the Pythagorean theorem was a very good instance of deductive reasoning.

Euclid argued in such a way that if all his postulates were true, then the Pythagorean theorem must also be true, with no room for doubt. If you change the postulates then the Pythagorean theorem may no longer be true.

Euclid was applying deductive reasoning to geometry. However, such standards for arguments cannot always be met successfully. In a good non-deductive argument, if the premises are all true, you would rightly expect the conclusion to be true also, though you would accept that it may be false. If you like, think of non-deductive arguments in terms of bets. If the premises of a good non-deductive argument are true, then you would be happy to bet that the conclusion is also true.

The argument would have provided you with the confidence that your bet is a sensible one, but — since it is a bet, after all — you would accept that the conclusion may turn out false and you may lose. As with deductive arguments, there are phrases people may use to indicate that arguments are non-deductive. The greediest person who was left alone in the room is Aunt Mary. Chances are that Aunt Mary is the one who stole the apple tart.

So the next one we expect to be a widower. This content is taken from The University of Auckland online course. See other articles from this course. This article is from the online course:. Join Now.

News categories. Other top stories on FutureLearn. Category: General. We take a closer look at media literacy and what makes it so important in …. Register for free to receive relevant updates on courses and news from FutureLearn. Create an account to receive our newsletter, course recommendations and promotions. Register for free. Hence, Jim is at home. Deductive arguments: The support the premises provide to the conclusion in a deductive argument is an all or nothing affair.

A valid deductive argument is an argument such that it is impossible for the premises to be true and the conclusion false, i. If it snows, then it's cold 2. It snows 3. Hence, it's cold. NOTE: An argument can be valid even if its premises and conclusion are false.

Informal testing for deductive validity: If you can describe circumstances, even fictional ones, in which the premises are true and the conclusion false, then the argument is invalid.

In other words, if you can consistently deny the conclusion while affirming the premises, the argument is invalid. Brown confessed to the murder. While 4 is most likely true if the premises are true, the argument is nevertheless not valid.

In fact, imagine the following. The witnesses have been bought off by George with the promise of free trips to Florida. Brown has been drugged by George with a chemical that convinced Brown he is the murderer. Non-deductive arguments Non-deductive arguments are deductively invalid because the truth of the premises does not guarantee the truth of the conclusion.

The support provided for the conclusion in a non-deductive argument is a matter of degree : the truth of the premises makes the truth of the conclusion more or less probable.

Thus, non-deductive arguments are either strong or weak. The premises of a strong non-deductive argument make it probable that the conclusion is true. There are two types of non-deductive arguments: inductive and abductive.

Examples of inductive arguments: 1. All observed emeralds have been found to be green 2. Therefore, the next observed emerald will be green. In the past, sugar cubes have dissolved in water 2. Thus, this sugar cube will dissolve in water. Jim is a SIUE student. Begin typing your search term above and press enter to search. Press ESC to cancel. Skip to content Home Philosophy What is the difference between deductive and non-deductive arguments?

Ben Davis April 8, What is the difference between deductive and non-deductive arguments?



0コメント

  • 1000 / 1000