PHL105Y Introduction to Philosophy Monday, September 18, 2006

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PHL105Y Introduction to Philosophy Monday,
September 18, 2006

• Announcements
• If you are new in the class today, welcome.
  Please take a syllabus from the desk at the
  front.
• For Wednesdays class, read chapters 4 and 5 of
  Vaughns Writing Philosophy
• Philosophy Party Wednesday, September 20, North
  Building Lounge (NB 262) 300-430 pm. All
  philosophy students welcome.
• Tutorials begin Friday. Your first tutorial
  assignment is due, in hard copy, at the beginning
  of your tutorial.

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Your first tutorial assignment

• You are asked to paraphrase a difficult textual
  passage. You may not understand the passage well
  the first time you read it. Do your best with
  it its OK this time if you dont succeed in
  writing a paraphrase that fully conveys the
  meaning of the original passage. In Fridays
  tutorial youll have a chance to go over anything
  you didnt understand.
• You are also asked to define some key terms
  (validity, etc.) be sure to explain these ideas
  in your own words.

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Handing in tutorial work

• Tutorial assignments are not submitted to
  www.turnitin.com (but of course original work is
  still required).
• Tutorial leaders will collect your written work
  every week.
• Four times a year, on weeks chosen (randomly) in
  advance, your tutorial work will be given a grade
  out of 10. The 10 of the final grade devoted to
  tutorial written work comes out of these
  assessments.
• Late tutorial work is not accepted without a
  documented excuse (e.g. MDs note).
• In an emergency, tutorial written work can be
  handed in by email before your scheduled
  tutorial.

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Your tutorial leaders

• David Dedourek TUT201, TUT204, TUT207
• Catherine Manoukian TUT206, TUT205
• Suzan Poyraz TUT202, TUT203
• Contact information on your TAs is available by
  clicking the office hours link on the main
  CCNet menu for the course. http//ccnet.utoronto.c
  a/20069/phl105y5y0201/
•  
• TUT201 FR1100-1200NE 297    
• TUT202 FR1200-1300NE 259     
• TUT203 FR1000-1100NE 257     
• TUT204 FR1400-1500NE 269     
• TUT205 FR1500-1600NE 295     
• TUT206 FR1200-1300NE 295     
• TUT207 FR1300-1400NE 297

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The Structure of Arguments
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The building blocks of arguments

• Arguments are composed of statements or
  propositions
• A statement something that could stand as an
  independent declarative sentence it is the sort
  of thing that can be true or false (unlike a
  question, command or exclamation).

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The building blocks of arguments

• There are two kinds of statements in any
  argument
• 1. Premises statements intended to function as
  reasons in support of a conclusion (ideally, your
  premises should be statements the reader is
  likely to accept already)
• 2. Conclusions statements intended to follow
  from your premises the aim of any argument is to
  drive the reader to accept the conclusion

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The building blocks of arguments

• 1. Premises can be marked with words like
  because, assuming that, since
• 2. Conclusions can be marked with words like
  therefore, so it follows that, as a result
• Caution often those marker words are absent you
  have to read the whole passage to get the gist of
  the argument and figure out which statements are
  premises and which are conclusions.

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Valid Deductive Arguments

• In a VALID deductive argument, IF the premises
  are true, the conclusion MUST also be true. A
  valid deductive argument CANNOT simultaneously
  have true premises and a false conclusion.
• In calling an argument valid we are saying that
  IF you accept the premises, you must accept the
  conclusion (a valid argument can have a false
  conclusion, as long as it has at least one false
  premise).
• If there is any logically possible way that the
  premises could be true, and the conclusion false,
  then the argument is deductively INVALID.

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SOUNDNESS

• A SOUND argument is a deductively VALID argument
  with all TRUE premises.
• Soundness is a higher standard than deductive
  validity all sound arguments are deductively
  valid, but not all deductively valid arguments
  are sound
• (Which deductively valid arguments are unsound?)

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Valid Deductive ArgumentsSome basic forms (there
are many others)

• Modus ponens
• If p then q
• p
• Therefore, q
• p and q each represent a statement.

• Modus tollens
• If p then q
• Not q
• Therefore, not p

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Antecedents and consequents

• The antecedent is the hypothetical condition of a
  conditional (the statement usually preceded by
  if), the consequent is what will follow (the
  statement preceded by then but sometimes the
  then is just understood and is not explicit)
• Watch out that in English conditionals can be
  written not only in the form If A then B, but
  also in the form B, if A. Here A is still the
  antecedent, even though it appears after the
  consequent. Example Jane will be angry, if she
  hears the news. This statement is equivalent to
  If Jane hears the news, then she will be angry.
• Antecedent Jane hears the news.
• Consequent Jane will be angry.

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Valid deductive arguments

• If Roberta is late, she will not meet Henry.
• Roberta is late.
• She will not meet Henry.

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Valid deductive arguments

• If Roberta is late, she will not meet Henry.
• Roberta is late.
• She will not meet Henry.
• If p then q
• p
• Therefore, q
• Note that p and q might be statements
  containing one or more negations e.g. it is
  not raining She is not unlikely to fail.

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Denying a statementwhen double negations cancel
out

• Where the original statement is negative (e.g. p
  Sarah will not testify against her brother) a
  denial of the statement gives you a double
  negation (so not-p It is not the case that
  Sarah will not testify against her brother.)
  Wed usually simplify that to Sarah will testify
  against her brother.
• How do double-negations work in the context of
  the argument forms we have learned?

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Two fallacies to avoid affirming the consequent,
denying the antecedent

• Affirming the consequent
• If p then q
• q
• Therefore, p
• Example If Paris steals, then she is breaking
  the law. Paris is breaking the law. Therefore
  she is stealing.

• Denying the antecedent
• If p then q
• Not p
• Therefore, not q
• Example if Jane is taking chemistry, then she is
  a student. Jane is not taking chemistry.
  Therefore, Jane is not a student.

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Test yourself

• The following arguments are either valid (modus
  ponens, modus tollens) or invalid (affirming the
  consequent, denying the antecedent). Which is
  which?
• If Morris tells the police what he knows, Jake
  will be arrested. Morris will not tell the
  police what he knows. Jake will not be arrested.
• If she fired the gun, Lucy will have gunpowder
  residue on her hands. Lucy does not have
  gunpowder residue on her hands. Lucy did not
  fire the gun.
• If Senator Carbuncle does not support the Budget
  Amendment, he will lose the support of his party.
  Senator Carbuncle supports the Budget Amendment.
  Senator Carbuncle will not lose the support of
  his party.
• If heterokonts are ancestrally photosynthetic,
  they are chromalveolates. Heterokonts are not
  chromalveolates. Therefore, they are not
  ancestrally photosynthetic.

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Test yourself

• The following arguments are either valid (modus
  ponens, modus tollens) or invalid (affirming the
  consequent, denying the antecedent). Which is
  which?
• If Morris tells the police what he knows, Jake
  will be arrested. Morris will not tell the
  police what he knows. Jake will not be arrested.
  (invalid, DA)
• If she fired the gun, Lucy will have gunpowder
  residue on her hands. Lucy does not have
  gunpowder residue on her hands. Lucy did not
  fire the gun. (valid, MT)
• If Senator Carbuncle does not support the Budget
  Amendment, he will lose the support of his party.
  Senator Carbuncle supports the Budget Amendment.
  Senator Carbuncle will not lose the support of
  his party. (invalid, DA)
• If heterokonts are ancestrally photosynthetic,
  they are chromalveolates. Heterokonts are not
  chromalveolates. Therefore, they are not
  ancestrally photosynthetic. (valid, MT)

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Inductive arguments

• In an inductive argument, the premises make the
  conclusion probable if the premises are true,
  the conclusion is likely to be true as well
  (although it is logically possible that the
  conclusion might be false).

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Types of inductive argument

• Enumerative induction
• Example 99 of Canadians watch television at
  least once a week. John is Canadian. John
  probably watches television at least once a week.
• Q What makes an argument of this type a strong
  argument?

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Types of inductive argument

• Argument by analogy
• Example The wise person does not deprecate life
  nor does he fear the cessation of life. The
  thought of life is no offense to him, nor is the
  cessation of life regarded as an evil. And even
  as people choose of food not merely and simply
  the larger portion, but the more pleasant, so the
  wise seek to enjoy the time which is most
  pleasant and not merely that which is longest.
• --Epicurus, letter to Menoeceus
• Q What makes an argument of this type a strong
  argument?

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Types of inductive argument

• Inference to the best explanation
• Example Detectives found blood matching the
  victims on your coat. A shoe print matching
  your known shoe size was found at the scene of
  the crime. Your fingerprints were found on the
  knife. You had a strong motive to kill the
  victim. You are probably the person we are
  looking for in this case.
• Q What makes an argument of this type a strong
  argument?

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Evaluating inductive arguments

• Inductive arguments are evaluated as strong or
  weak.
• A strong inductive argument with true premises is
  said to be COGENT.

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Summary

• Statements are true or false.
• Deductive arguments are valid or invalid.
• Some valid arguments are sound some valid
  arguments are unsound.
• Inductive arguments are weak or strong.
• Some strong inductive arguments are cogent some
  fail to be cogent.

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Style and content in philosophical writing
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Common sense

• Why avoid highly complex and pretentious ways of
  saying things?

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How should we speak of Plato?

• When paraphrasing a famous author, what is the
  appropriate attitude to take towards that author?

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Fallacies to avoid

• What is the straw man fallacy?
• What is the ad hominem fallacy?

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Fallacies to avoid

• The straw man fallacy is committed when you
  attack a reduced version of your adversarys
  position instead of the real thing.
• The ad hominem fallacy is committed when you
  attack the personal characteristics of your
  opponent rather than her position itself.

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Clarity and coolness

• To keep your writing clear, it helps to read it
  out loud, and then fix anything that sounds
  awkward.
• Loaded emotional language is generally avoided in
  philosophy papers. (Why?)
• The Academic Skills Centre can help you learn to
  write (more) clearly drop in and see them (Room
  2115B, South Building)

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Assumptions

• Philosophy often involves raising questions about
  things commonly taken for granted. Be careful
  about letting your argument rest on popular
  sentiments that might not be shared by the
  philosopher you are discussing.

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The first person

• Yes, you can use the first person pronoun in your
  philosophy papers in fact, its often very
  useful to mark the boundaries between your
  thought and the ideas of the philosopher you are
  criticizing. (According to Descartes, the idea
  of God is innate in us. In this paper I will
  argue that)
• Claims you make in the first person still need to
  be backed up by rational argument.