1. Truth Tables (10 points)

Use Truth Tables to determine whether the following arguments are valid. Show your work (make an argument schema, make a truth table, fill it in, and then explain why it is or isn’t valid).

a)

1. The canvas is red and the paint is blue

2. Either the paint is not blue or the painting is purple

3. The painting is purple

b)

1. Either cats are the best pets, or cats are the second best pets and dogs are the best pets

2. If dogs are the best pets, then cats are the second best pets

2. Argument Diagramming (10 pts)

Diagram the following argument. First, identify the conclusion and all the premises and put them in numbered premise format. Identify any subarguments and then determine whether the premises are dependent or independent. 

“My mom’s lasagne is the best. She uses fresh mozzarella, and fresh mozzarella is very tasty. It’s definitely better than your mom’s lasagne, because your mom doesn’t use enough garlic, and she always overcooks it.”

3. Gricean Deduction (5 pts)

Suppose that you are invited to your friend’s house for a dinner party. After you get there, your friend says:

“Let me make us some drinks while we wait”

Name one proposition that is implicated but not expressed by that utterance. Describe how you would use the Gricean Deduction to confirm that the proposition is implicated (including naming which Gricean Maxim would be violated).

4. Analogical Reasoning with Samples (10 pts)

Put the following argument into the numbered argument format of analogical reasoning with samples. This involves identifying the sample group, the target group, and the feature. (7 pts)

“The University of Manitoba asked 20 people in Degree’s (the campus restaurant) whether or not the campus needs another restaurant. 7 of the people who were questioned answered “yes”. We can conclude that two thirds of people on campus don’t think the campus needs another restaurant.”

Do you think the sample group is in fact representative of the target group? Fully explain your answer using the concepts we went over in class. (3 pts)

5. Inference to the Best Explanation (10 pts)

Suppose you are trying to explain the following phenomenon: My indoor fern (houseplant) always thrives in the summers but struggles in the winter.

Consider the following four explanations. Identify which explanation is the best. For each of the other three explanations, explain which theoretical virtue it is most lacking.

1. This winter your fern struggled because there was a parasite infestation. Last winter your fern struggled because it was too close to the cold window, and the year before it struggled because you went on a long holiday and had your sister watch your plants for you and she brought her dog. 

2. Your fern struggles in the winter because you barely water it. However, your fern does well in summer because that’s when the garden gnomes are active and they come to life to take care of your fern when you’re not looking.

3. Your fern struggles in the summer because it doesn’t get enough sunlight. In the winter, the southern exposure allows for it to get lots of direct sunlight and thrive, but in summer the light doesn’t reach far enough into the room. 

4. Your fern struggles in winter because the air is too dry inside, which happens because you always have your heater running in winter. Ferns like humid air. In the summers, you don’t have to have your heater on, and so the air is humid enough for the fern then.