Testing Arguments Questions – Description
Written Response Testing Arguments, Ch. 3: Directions:
Read these two sample arguments and the analysis of them to help you understand these concepts. This is the indirect test. If you have forgotten the concept, go back to the Lecture and review it. You can also use Venn Diagrams to prove an argument if it is a Categorical Syllogism. To do this, read pages 230-252 in Chapter 7 in you text to learn how to use Venn diagrams.
Example: Deductive argument:
1)“Since Moby Dick was written by Shakespeare, and Moby Dick is a science fiction novel, it follows that Shakespeare wrote a science fiction novel.”
Valid X Invalid
Explain why: Deductive and valid, because the conclusion follows with strict necessity from the premises. If we assume our premises are true and our conclusion is false, we entail a contradiction since conclusion must follow and cannot be false.
Sound Unsound X
Explain why: The premises are false. If the premises were true then the conclusion would have to be true, and the argument would be sound (valid with all true premises).
Follow the same format for Inductive arguments. Explain whether it is strong or weak; cogent or uncogent.
2) “Statistics reveal that 89% of those who receive flu shots do not get the flu. Jack received a flu shot one month ago. Therefore, he should be immune, even though the flu is going around.”
Strong X Weak
Explain why: Assuming the premises true, the conclusion follows with strong probability and does not appear to be false.
Cogent X Uncogent
Explain why: Cogent because the premises are probably true, and reasonable.
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Written Response Testing Arguments, Ch. 3:
DIRECTIONS FOR THE EXERCISE; DO NOT DO THESE WITHOUT READING THE ABOVE SAMPLES:
Let’s look at some arguments. Tell me as much as you can about each one. For example, you can tell me its form, and that you recognize it as, say, Modus Ponens. Then you can try to evaluate its soundness as well. If you recognized it as MP then you know it is valid. If you recognized it as Affirming the Consequent, then you know it is invalid. You may not find a form. If you do not, this is the time to use the Indirect Test!! See Lecture on this. You can then proceed to tell me about its soundness. You can say things like, “the premises appear to be false, so this would make it unsound.” Or, “I don’t know if the premises are true or false, so if they are true the argument would be, let’s say, valid and sound, or if they are false, then it would be, say, valid and unsound.” You must justify you answer with a test procedure. A test is 1) finding a form or 2) the indirect test. It can also be 3) using a Venn diagram. Below are some exercises to complete:
Deductive:
1) Everyone who is well-educated knows about the existence of the Roman Empire, and John is well-educated. So, John must know something about the Roman Empire.
Valid Invalid
Explain Why
Sound Unsound
Explain Why
If Galileo invented quantum mechanics, then he was familiar with physics in the twentieth century. Galileo was not familiar with physics in the twentieth century. Therefore, Galileo did not invent quantum mechanics.
Valid Invalid
Explain Why
Sound Unsound
Explain Why
3. All robots are drudges
Some professors are robots
Therefore, Some professors are drudges.
Valid Invalid
Explain Why with a Venn Diagram (diagram the universal statement first)
Sound Unsound
Explain Why
Inductive:
3) Look at the footprints in the mud by the window. We must have a peeping tom.
Strong Weak
Explain Why
Cogent Uncogent
Explain Why
Texans must all wear cowboy boots. I went to Houston, Texas last Thursday, and everyone I say on the street had boots on.
Strong Weak
Explain Why
Cogent Uncogent
Explain Why
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