Logic and
Critical Thinking
Philosophy 4
Gale Justin
Chapter 3: Reading for Reasoning
Focuses exclusively on passages that provide support for a statement. Such passages contain what are called "arguments."
For example (based on 3.3):
S: Valuables were missing.
S: Door did not seem locked.
S: Pattern of scratches on driver’s door window
C: Steve’s car was probably burgled.
Example based on Amtrak derailment passage. p. 75:
S: An amtrak train derailed at the switch.
S: Bolt cutters and shavings that might be from a lock were found nearby.
S: The siding switch lock itself is missing.
________________________________________
C: A switch may have been tampered with.
When you are asked to "schematize" an argument, such as one of the arguments just stated, you put the argument in the following form:
S: Support
S: Support
S: Support
________________________________
C: Conclusion
Complex arguments:
An argument is complex when the support in an argument is itself supported.
Examples of complex argument:
S1: The killing was premediated.
S2:He had plenty of time to think about it.
S3: Several days prior to the murder, he bought the gun.
S4: There is no evidence that he is suffering from any mental disorder.
________________________________
C: He should get first degree murder.
Conventions for schematizing complex arguments:
1. Number support propositions in order of their occurrence.
2. Show by means of indentation that a proposition functions as support for another proposition that is itself only support for the argument’s conclusion.
More examples of complex arguments
Argument on p. 105:
S1:Tar of cigarette smoke interacts with lung tissue to initiate malignancy.
S2: Study shows this result.
______________________________
C: Smoking causes cancer.
And also p. 105, 3.5:
S1: Lowering water temperature provides the perfect environment for Legionella bacteria.
S2: In test case, only lowered systems had the bacteria.
S3: One of these bacteria colonies was eliminated with hot water.
____________________________
C: Lowering water heater temperature caused outbreak of Legionaires’ disease.
Schematize the complex argument in the following passage:
The outcome of the current battle over same sex marriage may depend on the high court’s acceptance of a parallel between opposite sex only marriage laws and the previously repealed ban on inter-racial marriage because there are similarities between the two types of restrictions. The ban on interracial marriage was based on the asserted superiority of the white race, just as the belief in the superiority of heterosexual couples may motivate the opponents of the same-sex marriage. Furthermore, both sets of law gathered support from arguments that appealed to the potential social harm inflicted on the children of such unconventional unions. So there are parallels between the now repealed inter-racial marriage ban and the present ban on same-sex marriage.
Can you construct an argument that supports the claim that there are differences between the two cases?
Argument Indicators:
1. Content indicators
a. passage concerns a controversial issue and offers a recommendation or proposal.
b. passage concerns the result of an investigation.
2.Flags: (See for practice exercise 3.18.)
a. Link flags: words like "therefore," "so," "thus," "hence," "it follows that."
b. Support flags: words like "because," "for," "since," "in as much as."
c. Conclusion flags (indirectness indicators) see p. 116
Recommendations/Proposals:
1. A basic form is: "We should do X (or we should not do x)."
2. Variations: ought/ought not; good idea/bad idea.
3. Recommendation can be in the form of an imperative: Vote yes on proposition 14 because it will provide safe schools.
4. For an example, see schematization of letter, p. 99.
Results of Investigations: inferences drawn from data, p. 120.
S1: There is a storm system south of Elko.
S2: Radar is showing rain across entire valley.
S3: Temperature is dropping along a line to the south.
S4: Normally this should bring rain.
________________________________
C: It will rain here tomorrow.
How to handle instances (see p. 107):
Proposition 11 would hurt small retailers. It would require them to limit stock. It would restrict shelf space. It would increase overhead. Moreover, there is no way of enforcing its provisions.
Here is one way to schematize:
S1: Proposition 11 would hurt small retailers.
S2: It would require them to limit stock.
S3: It would restrict shelf space.
S4: It would increase overhead.
S5 : There is no means of enforcing its provisions.
________________________________
C: Proposition 11 is a bad idea.
A simpler schematization:
S1: Proposition 11 would hurt small retailers by requiring them to limit stock, restrict self space, and increase overhead.
S2: There is no means of enforcing its provisions.
________________________________
C: Proposition 11 is a bad idea.
Conventions in these types of Arguments:
1. Number support propositions in order of their occurrence.
2. Show by means of indentation that a proposition functions as support for another proposition that is itself only support for the argument’s conclusion.
3. Omit link flags and support flags in schematization. Also omit words such as "think," "believe," etc (p. 115).
Homework: