1. Reasoning & Critical Thinking James Bednar Day 1

2. 2 What is logic? Logic is the study of methods for evaluating whether the premises of an argument adequately support (or provide evidence for) its conclusion.

3. 3 What is an argument? An argument is a set of statements, one of which, called the conclusion, is affirmed on the basis of others, which are called the premises.

4. 4 Example All Quakers are pacifists. Jane is a Quaker. So, Jane is a pacifist.

5. 5 What is a statement? A statement is a sentence that is either true or false. Some dogs are collies. (truth value = true) No dogs are collies. (truth value = false) Get off my lawn! How many dogs do you own? Let’s get a dog. Commands, questions, and proposals are sentences, but they are not statements.

6. 6 In sum Arguments are a series of statements. One of those statements is intended to be supported by the others. The rest are intended to give support.

7. 7 Uses of Argument Here are two: to persuade others to discover truth

8. 8 Galileo v. Aristotle Do heavier bodies fall faster than lighter ones? Aristotle: Yes Galileo: No

9. 9 Galileo v. Aristotle Salviati. If then we take two bodies whose natural speeds are different, it is clear that on uniting the two, the more rapid one will be partly retarded by the slower, and the slower will be somewhat hastened by the swifter. Do you not agree with me in this opinion? Simplicio. You are unquestionably right. Salviati. But if this is true, and if a large stone moves with a speed of, say, eight while a smaller moves with a speed of four, then when they are united, the system will move with a speed less than eight; but the two stones when tied together make a stone larger than that which before moved with a speed of eight. Hence the heavier body moves with less speed than the lighter; an effect which is contrary to your supposition. Thus you see how, from your assumption that the heavier body moves more rapidly than ' the lighter one, I infer that the heavier body moves more slowly. from Mathematical Discourses and Demonstrations (1628)

10. 10 A father and his son are involved in an automobile accident. Both are seriously injured and are rushed to separate hospitals. The son is immediately readied for emergency surgery; at first sight of him, however, the surgeon says, “I can’t operate on this patient—he’s my son!” How is what is reported here possible?