Logical Reasoning Lecture 3

# Logical Reasoning Lecture 3 - 1 Logical Reasoning Lecture#3...

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1 Logical Reasoning Lecture #3 I. Basic Argument Analysis (A) Introduction There are certain things we can know just by observation. For every fact who have observed, there are many more facts that you haven’t. How do you know that George Washington was the first president of the United States? How do you know that people have landed on the moon? Much of our knowledge comes from other people. Others observed these things and other have shared their knowledge with us through testimony. Some facts about the world go beyond the collective experience of people. Some examples include the following: the origin of life, the microscopic world of sub-atomic particles, and the distant reaches of space. None of these things have been directly observed. In order to have knowledge of them, we must proceed by means of reasoning. When we reason, we use the relationships between propositions to extend our knowledge.

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2 (B) Elements of Reasoning (1) Arguments In reasoning, we are concerned with arguments. In every day use, an argument is usually understood as a quarrel between two people. In our use, an argument involves an appeal to evidence in support of a conclusion. Example: the lawyer argued that OJ was guilty because of the DNA evidence. * An argument is a set of propositions in which some of the members of the set, the premises, are offered in evidential support of another member of the set, the conclusion. * The premises of an argument are the propositions that are offered in evidence for the conclusion. *The conclusion of an argument is the proposition that the premises are offered in support of. In some cases, we say that a conclusion is inferred from the premises. An argument is not merely a set of propositions. A story is a set of propositions and a story is not an argument.
3 An argument is not merely a set of premises. An argument is not merely a set of conclusions. Arguments involve both premises and conclusions. Some arguments can be stronger than others. With regard to argument strength - Just because an argument gives more examples does not make it a stronger or better argument. - False evidence is not evidence. False premises do not provide any support. - That an argument does not convince anyone does not mean that it has no strength. (2) Premises * The premises of an argument are the propositions that are offered in evidence for the conclusion. That is, premises are the reasons provided as evidence for the conclusion. Premises of an argument do not have to come first. Sometimes the conclusion is state first. Example: We have to go to the beach. This is the last weekend in the summer and it is a beautiful day out. Indeed, it is also possible for a premise to come at the end of the argument.

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4 In general, with an argument, there is no necessary order in which premises and conclusions must be placed. An argument must have at least one premise.
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Logical Reasoning Lecture 3 - 1 Logical Reasoning Lecture#3...

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