Review: an argument can have an unstated premise'

1
Deductive arguments and Unstated Premises

• Review an argument can have an unstated premise.
  
• For example, No motorcycles are allowed in the
  park because the regulations state that motor
  vehicles are not allowed entrance.
• No motor vehicles are allowed in the park.
• All motor cycles are motor vehicles. (We have to
  assume this premise)
• Therefore no motor cycles are allowed in the
  park.

2
Deductive arguments and Unstated Premises

• Review an argument can have an unstated
  conclusion.
• It is wrong to have hurt someones feelings, and
  that is exactly what you are doing when you speak
  to me like that.
• Why is this a deductive argument instead of an
  inductive argument?
• What do we mean when we say something like,
  Murder is wrong.? Do we generally mean that
  murder is sometimes wrong? Or do we mean that it
  is sometimes wrong for me, but it might be right
  for you? We have to put things in context and
  think what the person saying it really means.
• All times that you hurt someones feelings are
  times you have done something wrong.
• This is a time when you hurt someones feelings.
• Therefore, this is a time that you have done
  something wrong.

3
Inductive or Deductive argument?

• 1. I have never taken a philosophy class that
  was not fun. I bet all philosophy classes are
  fun.
• Inductive
• 2. Since some apples are red, and all apples are
  fruit, some fruit is red.
• Deductive
• 3. All mammals are warm blooded creatures, and
  all whales are mammals. Therefore, all whales
  are warm blooded creatures.
• Deductive
• 4. Fulcher lives in Alaska. Therefore, he uses
  mosquito repellent.
• Inductive

4
Your turn

• I will hand you each a piece of paper. They will
  have either the word inductive or deductive
  on them. Depending on which paper you get, you
  will come up with an appropriate argument. The
  rest of the class will try to guess which type of
  argument it is. I want you to turn them in at the
  end of class because I might use one or two of
  them for an extra credit question on the test.

5
Practice quiz

• If you log in to http//elearning.ipfw.edu then
  you can take a practice quiz. In the meantime,
  lets go over some problems.
• Do all arguments have a conclusion?
• Yes, but it may not be explicitly stated.
• Are all valid arguments sound arguments?
• What is the difference between a valid argument
  and a salad argument?
• No. Can you think of an example?
• If the moon were made of green cheese, then the
  cow will jump over the moon.
• The moon is made of green cheese.
• Therefore, the cow will jump over the moon.

6
Explanations and Arguments

• Do explanations and arguments serve the same
  purpose?
• No
• Why not? What purposes do each of them serve?
• Basically, an argument attempts to support or
  prove a conclusion, while an explanation
  specifies what caused something or how it works
  or what it is made of and so forth. Arguing that
  the computer is working much more slowly than it
  used to is not the same as explaining what caused
  the computer to start working much more slowly.