Chapter Summary

The aim of argument reconstruction is to clarify, and make fully explicit, the argument intended by an arguer. We do this by putting the argument into standard form. If our main concern is whether or not the conclusion of the argument is true, then our reconstruction should be guided by the Principle of Charity: we should aim for the best possible reconstruction of the argument.

In order to do this, we need precise concepts in terms of which to assess arguments. We need, to begin with, the concepts of truth, deductive validity, and deductive soundness. A

deductively valid argument (a valid argument for short) is one whose premises could not possibly be true without the conclusion being true also. A deductively sound argument is a valid argument with true premises. It follows that a deductively sound argument must have a true conclusion.

Individual propositions can be true or false, but not valid or invalid. Arguments can be valid or invalid, but not true or false. Conditional propositions are not arguments, but single propositions: a conditional proposition is a single proposition made up of two propositions, the antecedent and consequent. Typically the antecedent and consequent of a conditional proposition are joined by 'if-then', but many other devices can do the same job. The crucial thing is the logical relationship between them.

Arguments do stand in a certain relationship to conditional propositions. If the argument is valid, then this conditional proposition is true: If the argument's premises are true, then its conclusion is true.

Logic: deductive validity

1 Study the section that describes the Principle of Charity. Then, without looking at the section again, and in your own words, write a short essay of about 250 words that explains the principle, and why it should be observed.

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