XS 100 - Week 10 Lecture 1 - 10-23-12

CONTINUING with Chapter 6,
fallacies of insufficient evidence:

*   fallacy of WEAK ANALOGY
----------------------------
*   the fallacy of weak analogy occurs when an arguer
    compares 2 or more things that aren't really
    comparable in relevant respects

*   occur in many forms,
    but are 3 particularly common patterns:
    1.  2 things with several identified similarities
 
        basic pattern:

	1. A has characteristics w, x, y, ..., and z
        2. B has characteristics w, x, y, ...
	3. Therefore, B probably has characteristic
	   z, too.

        NOTE this pattern is NOT NECESSARILY
	fallacious --
	if w, x, y, ... are RELEVANT to z being the case,
	this pattern can be a good inductive argument
	pattern, argument by analogy;

	BUT if w, x, y, ... are NOT relevant to z being
	the case, THAT's when you can have the fallacy
	of weak analogy here;

    2.  several things that have only 1 or 2
        identified similarities;

        pattern:
	1. A is/has/does x, and A is/has/does y.
	2. B is/has/does x, and B is/has/does y.
        3. C is/has/does x, and C is/has/does y.
        ...
        4. D is/has/does x.
        5. Therefore, D probably is/has/does y, too.

        AGAIN -- this CAN be a reasonable pattern
	for an inductive argument by analogy --

	BUT, are there important DIFFERENCES between
	A, B, C and D that are relevant to the conclusion
	being argued?
        (is there an important difference in D's
	case that weakens the possibility that
	D is/has/does y?)
        
    3.  to simply assert, without further elaboration,
        that two cases are relevantly similar;

        to critically evaluate THIS case --
	to see if you have a reasonable analogy,
	or a WEAK one --
	you need to do 3 things:
        1.  list the important similarities between
	    the things being compared.
        2.  list the important dissimilarities 
            (differences) between the things being
	    compared.
        3.  decide whether the the similarities
	    or the differences are more important
	    with regard to the conclusion
	    (consider the relevant differences
            and similarities between the cases)

Inconsistency
--------------
*   The fallacy of inconsistency occurs when an
    arguer asserts inconsistent or contradictory
    claims
    (where inconsistent = cannot both be true)

*   notice that this fallacy can be due
    to a self-contradictory claim,
    as well as to combinations of premises that,
    taken together, are inconsistent;

CHAPTER 7 -- ANALYZING ARGUMENTS
---------------------------------
*   we STARTED this process already,
    in breaking an argument into its premise(s)
    and conclusions;

*   now we are formalizing this a bit further,
    and further analyzing these pieces;

*   to analyze an argument,
    we mean to break it down into its various
    parts to see clearly what conclusion is
    defended and on what grounds;

*   this chapter gives TWO approaches to this:
    one suitable for shorter arguments:
    *   diagramming arguments
    one suitable for longer arguments:
    *   summarizing arguments

diagramming [usually short] arguments
-------------------------------------
*   short = a paragraph in length or shorter...

*   basic approach:
    1.  Read through the argument, CIRCLE or otherwise
        indicate any premise or conclusion indicators
	that you see.
        (later in class, we decided that we will
	UNDERLINE any premise or conclusion indicators
	that you see)

    2.  Number the statements consecutively as they
        appear in the argument
	(numbers in parentheses, e.g., (2), or in
	circles)

    3.  Arrange the numbers withn premise-numbers
        placed ABOVE the conclusion-numbers they
	support --
	IF you see that a statement is not logically
	relevant to any conclusion,
	you just omit it at this point.

    4.  add arrows between the premises and conclusions,
        such that:
	if a premise, all by itself, independently
	supports the conclusiion, draw an arrow from
	that premise number to that conclusion number

	if a collection of premises work TOGETHER to
	support a conclusion, underline their numbers
	and put a plus + betwen them, then draw
	an arrow from the underline to the supported
	conclusion

    The death penalty should be abolished because
    it is racially discriminatory, there's no evidence 
    that it is a more effective determinant than life
    imprisonment, and innocent people may be executed by
    mistake.

    (1) The death penalty should be abolished because
                                              -------
    (2) it is racially discriminatory, (3) there's no 
    evidence 
    that it is a more effective determinant than life
    imprisonment, and (4) innocent people may be 
    executed by mistake.

    (2)  (3)  (4)

         (1)

    (1) If Amy runs marathons, then she's probably very
    fit. (2) Amy does run marathons. (3) She's also 
    a B student.
    So, (4) Amy is probably very fit.
    --
   
      (1)     (2)
          (4)

*   we'll talk more about the ARROWS needed to
    complete these argument diagrams on Thursday;