Logic

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Propositions are the material of our reasoning. It asserts that something is (or is not) the case. Any proposition may be affirmed or denied.

As logicians use the word an argument is any group of propositions of which one is claimed to follow from the others, which are regarded as providing support or grounds for the truth of that one. For an argument to be present there must be some structure within the cluster of propositions, a structure that captures or exhibits some inference. This structure we describe using the terms premise and conclusion.

The conclusion of an argument is the proposition that is affirmed on the basis of the other propositions of the argument. Those other propositions, which are affirmed (or assumed) as providing support for the conclusion, are the premises of the argument.

The simplest kind of argument consists of one premise and a conclusion. Each may be stated in separate sentences:

No one was present when life first appeared on earth. Therefore any statement about life’s origins should be considered as theory, not fact.

Or both the premise and the conclusion can be stated in one sentence:

Since it turns out that all humans are descended from a small member of African ancestors in our recent evolutionary past, believing in profound differences between the races is as ridiculous as believing in a flat earth.

The statements of the argument’s conclusion may precede its statement of its single premise.

The Food and Drug Administration should stop all cigarette sales immediately. After all, cigarette smoking is the leading preventable cause of death.

Even when premise and conclusion are united in one sentence, the conclusion of the argument may come first.

Every Law is an evil, for every law is an infraction of liberty.

(------Alright eto na yung exercise! LOL -----(

Exercises: (--first toh. May sagot yung number 1 as an example--(

Identify the premises and conclusions in the following passages, each of which contains only one argument.

Example:

1. A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed.

Solution:

Premise: a well regulated militia is necessary for the security of a free state.

Conclusion: The right of the people to keep and bear arms shall not be infringed.

2. We can avert a majority of cancers by prevention efforts, even if we never get straight on the causes; more research on prevention and less on cure makes increasing sense.

3. Good sense is of all things in the world the most equally distributed, for everybody thinks himself so abundantly provided with it that even those most difficult to please in all other matters do not commonly desire more of it than they already possess.

4. Of all our passions and appetites the love of power is of the most imperious and unsociable nature, since the pride of one man requires the submission of the multitude.

5. Forbear to judge, for we are sinners all.

6. In preparing for the national census of 2000, intense disagreement arose over whether the U.S. Constitution requires an actual head count of the population, or whether a sophisticated sampling technique might reasonably replace the headcount. A letter to the New York Times on 6 September 1998 contained the following argument: With the “head count” method, the Census Bureau cannot succeed in counting all the people in the United States. Therefore the “head count” system is itself a sampling method, in which the sample is the portion of the population that actually returns the questionnaire.

7. Human cloning – like abortion contraception, pornography, in vitro fertilization, and euthanasia – is intrinsically evil and thus should never be allowed.

8. Sir Edmund Hillary is a hero not because he was the first to climb Mount Everest but because he never forgot the...
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