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A Little Logic

A Little Logic. Identifying Parts of Arguments. Arguments are made of parts: ・ Premises (or support) ・ Conclusion (or result) ・ Inference (mental movement from premises to conclusion) . Premises. Inference. Conclusion. Deductive Arguments. Premises. Conclusion.

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A Little Logic

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  1. A Little Logic

  2. Identifying Parts of Arguments Arguments are made of parts: ・Premises (or support) ・Conclusion (or result) ・Inference (mental movement from premises to conclusion) Premises Inference Conclusion

  3. Deductive Arguments Premises Conclusion

  4. Types of Arguments: Deductive and Inductive Deductive Premises If there’s time in the day, I’ll bepleased. If I am pleased, then life is worth living. Conclusion If there is time in the day, then life is worth living.

  5. (2 x 150)/30 = 30

  6. Inductive Arguments Premises Conclusion

  7. Inductive Premise: Seventy-five percent of all 8.0 or greater magnitude earthquakes studied in the last 50 years have had 10 to 20 aftershocks per day, leading to one major 8.0 magnitude aftershock within 1 year of the initial quake. Conclusion: Therefore, the 9.0 earthquake of 11 March 2011, off the coast of Sendai, Japan, will result in a major aftershock of 8.0 magnitude.

  8. Premise indicators: • as indicated by… • as… • because… • for the reason that… • for… • given that… • in that… • inasmuch as… • may be inferred from… • owing to… • seeing that… • since…

  9. Conclusion indicators: • accordingly, … • as a result, … • consequently,… • entails that… • for this reason, … • hence, … • implies that… • it follows that… • it must be that… • so… • therefore,… • thus, … • we may conclude… • we may infer that… • wherefore…

  10. Sincethe good, according to Plato, is that which furthers a person’s real interests, It follows that in any given case when the Good is known, men will seek it. (from Avrum Stroll and Richard Popkin, Philosophy and the Human Spirit)

  11. A dog was kept in the stalls, and yet, though someone had been in and fetched out a horse, the dog had not barked. Obviously, the visitor was someone thedog knew well… (Sherlock Holmes, The Adventure of the Silver Blaze)

  12. It is difficult to gauge the pain felt by animals, because pain is subjective and Animals cannot talk.

  13. Modus Ponens • If p, then q. • P • Therefore, q Here is an example: • If the USA continues to invade other Muslim countries, then its prestige and image will fall in the Muslim world. • The USA does continue to invade other Muslim countries. • Therefore, the prestige and image of the USA will fall in the Muslim world.

  14. Modus Tollens • If p, then q. • Not q. • Therefore, not p. • If children today are intensively taught cursive writing, then they will be able to read cursive writing. • But children today have a difficult time reading cursive writing. • Therefore, children today are not taught cursive writing very intensively.

  15. Hypothetical Syllogism • If there’s time in the day, I’ll bepleased. • If I am pleased, then life is worth living. • Therefore, if there is time in the day, then life is worth living. • If p, then q. • If q, then r. • Therefore, if p, then r.

  16. Disjunctive Syllogism • Either I will buy a BMW or a Mercedes. • I decided not to buy a Mercedes. • Therefore, I decided to buy a Mercedes instead. • p or q • Not q. • Therefore, p.

  17. Constructive Dilemma • If we pollute the environment, human health will decline, but if we recycle, then human health will improve. • Either we pollute or we recycle. • Therefore, either human health will decline or it will improve. • If p, then q and if r, then s. • p or r • Therefore, q or s.

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