Strategies for Assessing Arguments

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Chapter 5

• Strategies for Assessing Arguments

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Strategies for Assessing Arguments

• There are essentially two main ways to assess
  arguments
• The fallacies approach
• The criterial approach

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Strategies for Assessing Arguments

• The fallacies approach
• A fallacy (defn) is a mistake in reasoning.
• According to this approach, we assess the
  soundness of an argument by determining if the
  reasoning employed in the argument commits any
  fallacies.
• Many of the more common fallacies have their own
  names.

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Strategies for Assessing Arguments

• E.g., argumentum ad misericordiam (appeal to
  pity)
• Student to teacher I ought to get an A on this
  paper. After all, I need an A average to keep my
  scholarship.

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Strategies for Assessing Arguments

• The criterial approach
• This approach looks at the criteria a good
  argument must satisfy true premises and logical
  strength.
• What are the criteria by which we determine
  whether the premises are true, and whether the
  reasoning employed has logical strength.

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Strategies for Assessing Arguments

• There are 3 criteria to a sound argument
• 1. The premises must be acceptable
• Are the premises true? Are they probable?
• 2. The premises must be relevant
• Are the premises relevant to the conclusion?
  Even if the premises are true, and they relevant
  to the conclusion that is being drawn?
• 3. The premises must be adequate
• And even if the premises are true and relevant,
  are they adequate by themselves to yield the
  conclusion, or does more need to be added?

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7 Rules in Assessing Arguments

• Identify the main conclusion
• Identify the premises
• Identify the structure of the argument
• Check the acceptability of the premises
• Check the relevance of the premises
• Check the adequacy of the premises
• Look for counter-arguments

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Chapter 6

• Assessing Truth Claims

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Theories of Truth

• The 4th rule requires that we assess the
  acceptability of the premises i.e., determine
  whether the premises are true, or likely to be
  true.
• But what is truth?

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Theories of Truth

• There are several competing theories of truth
  theories about the nature of truth, and how it
  works.
• The 3 most commonly held are
• Correspondence
• Coherence
• Pragmatic

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The Correspondence Theory of Truth

• This is probably the most widely held and
  intuitively plausible account of truth
• This theory states a statement is true iff it
  corresponds to the facts.
• E.g.
• There are 10 coins in my pocket is true iff it
  is a fact that there are 10 coins in my pocket.

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The Correspondence Theory of Truth

• The main thought behind this theory is that there
  are facts which make statements true, which the
  statements correspond to.
• Some problems
• What about negative statements?
• There are no potatoes in this room.
• What about moral statements?
• You ought to keep your promises.
• What about counterfactuals?
• If Hitler had died in 1928, there would not have
  been WWII.
• What about statements about nonexistent entities?
• There are no unicorns.

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The Correspondence Theory of Truth

• Some more problems
• What is a fact?
• What is correspondence?
• And, dont we already have to have the notion of
  truth in order to assess correspondence?

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The Correspondence Theory of Truth

• Nevertheless
• The correspondence theory seems to be a workable
  model for empirical statements, so long as we
  accept that there are empirical facts.
• An empirical fact is a fact that is in principle
  observable.

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The Coherence Theory of Truth

• This theory states a statement is true iff
  coheres with my other beliefs.
• According to this theory, the reason we hold any
  particular statement to be true is because there
  are other beliefs that we have which justify our
  belief that it is true.
• I believe A is true because of belief B, and B is
  true because of belief C, etc.

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The Coherence Theory of Truth

• The main thought behind this theory is not
  correspondence, but rather consistency.
• Two (or more) statements are said to be
  consistent (defn) iff they can be held true at
  the same time.
• The reason we accept any particular statement is
  because it is consistent with our other beliefs.
  If it is not consistent, then it is rejected as
  false.
• Coherence is an internal criterion of truth,
  while correspondence is an external criterion.

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The Coherence Theory of Truth

• Problem
• Granted, if all your beliefs are true, they will
  form a consistent system
• But it does not follow that if your beliefs are
  consistent that they are all true! (i.e., you
  could have a consistent set of beliefs that are
  all false).

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The Coherence Theory of Truth

• E.g.
• Dogs are birds, Birds have 4 legs, All
  4-legged creatures are crustaceans
• The sentence Dogs are crustaceans coheres with
  the sentences in the above set, but clearly it is
  not true!
• Why not? It doesnt correspond to the facts?

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The Pragmatic Theory of Truth

• This theory states a statement is true iff it
  leads to the successful solution to a real
  problem.
• Or better a statement is true iff it works.
• One of the thoughts behind this theory is that
  the nature of reality is not something that we
  have direct access to, and that there is no way
  to compare our beliefs with how things really are
  (i.e., pragmatists reject the correspondence
  theory).

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The Pragmatic Theory of Truth

• Nevertheless we have to cope with our
  environment.
• Therefore, take as true those statements which
  help us cope.

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The Pragmatic Theory of Truth

• E.g.
• There is some debate in science as to the nature
  of quantum theory.
• Since we are dealing with stuff that is really
  really small, we cannot empirically verify it.
  (cannot use correspondence)
• Quantum theory notoriously contravenes some of
  our most strongly held logical and physical
  convictions (i.e., does not cohere with other
  beliefs)
• Nevertheless is it extremely accurate in making
  predictions.
• It is because of this usefulness, its
  instrumental value, that it is accepted by
  scientists as true.

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The Pragmatic Theory of Truth

• Some problems
• Some statements arent useful at all, but
  nevertheless are clearly true.
• Isnt it because a sentence is true that it is
  useful, and not the other way around?

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Theories of Truth

• Despite the problems with these 3 theories, when
  assessing truth, we should be on the look out for
  these following features
• Can it be empirically verified?
• If not, does it cohere with the rest of my
  beliefs?

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Types of Truth Claims

• The truth or falsity of a statement is
  independent of our knowledge of its truth or
  falsity.
• If we can determine that a statement is true,
  then it has been verified (it is true, and we
  know it is true).
• If we can determine that a statement is false,
  then it has been falsified (it is false, and we
  know it is false).
• If we cannot determine whether a statement is
  true or false, then it is undetermined.
• If a statement is undetermined, it is still
  either true or false, we just do not know, or
  possibly cannot know, which.

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Types of Truth Claims

• There are two main types of truth claims
• Empirical
• Non-empirical

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Empirical Truth Claims

• A claim is an empirical claim if it can verified
  by checking the facts.
• E.g.
• There are at least 10 books in my office.
• My car is blue.
• Mt. Everest is the tallest mountain on earth.

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Empirical Truth Claims

• Some empirical claims are easier to verify (or
  falsify) than others.
• E.g.
• England will beat Switzerland tomorrow
• It was 12 degrees in Antigonish 150 years ago.
• There is life on other planets.

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Empirical Truth Claims

• These examples are about things in the past, the
  future, or places that are too far away.
• Those examples are clearly empirical claims. We
  can verify their truth by empirical factsthe
  problem is that we do not have direct access to
  those facts.
• These claims will have to be verified indirectly.

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Empirical Truth Claims

• Besides particular empirical claims (about books
  in my office, or the colour of my car, or the
  weather in Antigonish on a particular date),
  there are also general empirical claims.
• 2 types of general empirical claims
• statistical empirical claims
• universal empirical claims

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Statistical Empirical Claims

• These are claims that talk about part of or some
  proportion of a class of things.
• E.g.
• The majority of philosophy majors are male.
• A quarter of Blue Jays die within the first year
  of their life.

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Statistical Empirical Claims

• Statistical empirical claims can be verified
  without having to check every particular fact.
  E.g., we dont have to examine every philosophy
  major, or every Blue Jay.
• These claims can be verified using statistical
  information.
• In particular, these claims are verified by using
  inductive generalizations generalizing from a
  sample to the whole.

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Universal Empirical Claims

• These are claims that talks about ALL of a class.
• E.g.
• All diamonds have a refractive index of 2.417
• All swans are white.

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Universal Empirical Claims

• Unlike statistical claims, universal claims can
  be falsified by a single exception.
• If there is one diamond which does not have a
  refractive index of 2.417, then the claim All
  diamonds have a refractive index of 2.417 is
  false.
• But of course if there is one Blue Jay which does
  not die before it is 12 months old, you havent
  shown anything about A quarter of Blue Jays die
  within the first year of their life.

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Universal Empirical Claims

• Universal empirical claims therefore cannot be
  verified (in principle), but they can be
  falsified.
• We could tentatively accept a universal empirical
  claim if the attempt to falsify it fails, but
  that acceptance should always be tentative.

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Non-empirical Truth Claims

• Non-empirical truth claims are truth claims which
  arent empirical.
• That is, they are claims which cannot be verified
  (or falsified) by evidence that comes to us from
  our senses.

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Non-empirical Truth Claims

• There are many sorts of such claims
• Analytic and contradictory statements
• Ethical statements
• Aesthetic statements
• Religious statements
• Foundational (first) principles

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Acceptability

• The question we need to ask when assessing a
  premise of an argument is Are we justified in
  accepting it?
• There are various standards of acceptability of
  truth-claims.
• These standards will depend on the type of claim
  as well as the context.

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Acceptability

• Strict proof this is the most demanding
  standard.
• This standard in common in mathematics, logic and
  some sciences, e.g.
• Common knowledge these have the least demanding
  standard.
• Nevertheless, they can sometimes be challenged.

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Common knowledge

• If common knowledge is challenged
• Determine why it is being challenged
• Is your interlocutor merely wasting your time
• Or is the argument precisely about this sort of
  claim (philosophy, e.g., is notorious for
  challenging claims that are thought to common
  sense)
• Context will usually determine this
• If the claim is not common knowledge, be prepared
  to offer the evidence as is required by the
  context.