aa05d14f   
   XPost: alt.philosophy, talk.philosophy.misc, alt.atheism   
   XPost: alt.christnet   
   From: reanimater_2000@yahoo.com   
      
   On Dec 25, 8:56 am, TheInquirer  wrote:   
   > On 25/12/2012 11:34 PM, Immortalist wrote:   
   >   
   > > On Dec 25, 2:44 am, TheInquirer  wrote:   
   > >> On 25/12/2012 4:03 AM, Immortalist wrote:   
   >   
   > >>> In science the null hypothesis or default theory is just a way to   
   > >>> start from scratch and then see what the evidence supports. Its a way   
   > >>> to avoid dogmatic bias.   
   >   
   > >> won't that be out of the frying pan, into the fire?   
   >   
   > > No.   
   >   
   > why no?  if the null hypothesis is used to support the null hypothesis,   
   > isn't that circular argument?  and wouldn't this procedure increase   
   > dogmatic bias?   
   >   
      
   possible worlds   
      
   > >> if the null hypothesis is not rejected, does that mean that   
   > >> the null hypothesis is true?   
   >   
   > > No, it just weakens the theory it challenges.   
   >   
   > i thought null hypotheses are set up to be rejected, in a   
   > sort of probabilistic "prove by contradiction" manner?   
   >   
      
   No. it is really a test of how well the theory makes any other theory   
   less likely or even impossible. We must tighten our hypothesis in ways   
   that make the null alternatives less likely or even impossible. Once   
   the remaining counter-theories sound supernatural our hypothesis   
   become null-proofed.   
      
   The method of counterexample and possible worlds   
      
   ...First, we need a test for invalidity, that is, a method of showing   
   that the conclusion of an argument does not follow validly from the   
   premises. The technique we shall adopt is known as the method of   
   counterexample.   
      
   Finding a counterexample to an argument is a matter of imagining a   
   possible world in which the premises are true and the conclusion   
   false. The possibility of such a world shows the argument is invalid.   
   You can think of possible worlds as variants of our actual world. For   
   every way in which our actual world could have been different than it   
   is, there exists a possible world that is different in this way. For   
   example: The Iraq crisis might have led to the outbreak of the third   
   world war; therefore, there exists a possible world in which the   
   crisis led to the war. Reagan might not have been shot; therefore,   
   there exists a possible world where he was not shot. Your parents   
   might never have met; therefore, there is a world in which you were   
   never born. The expression, 'possible world,' is just a fancy way of   
   talking about the way things might be but actually are not. Possible   
   worlds are easily constructed: whenever you imagine some possible   
   alteration of the actual world, you construct a possible world that   
   differs in the altered respect from the actual world. Finding a   
   counterexample to a purportedly valid argument is a matter of   
   constructing a possible world in which the premises of the argument   
   come out true and the conclusion comes out false. This shows that it   
   is possible for the premises to be true and the conclusion false.   
      
   You can give your imagination wings in thinking up such worlds and   
   such examples, but you must not fly beyond the possible. A   
   counterexample need not be an example of anything that has ever   
   happened or of anything at all likely to happen. Just as long as the   
   example clearly describes something possible, a clearly possible world   
   in which the conclusion is false and the premises true, the argument's   
   claim to validity is refuted. You can refute invalid arguments by the   
   use of your imagination. Let us try this out. Consider the following   
   argument:   
      
   All Communists are opposed to capitalism.   
   Jones is opposed to capitalism.   
      
   Therefore   
   Jones is a Communist.   
      
   It is perfectly easy to describe a counterexample that shows that the   
   conclusion of this argument does not follow from the premises. Imagine   
   a possible world in which Jones is a person who believes that all   
   wealth and property should be owned and controlled by his family and   
   passed on by inheritance. Thus, he rejects both capitalism and   
   communism in favor of Jonesism, a heretofore unknown economic doctrine   
   which states that everything should belong to the Joneses. What is   
   described in this example is a possible world, and, supposing that   
   both the first and second premises are true, it is an example in which   
   the premises are true and the conclusion false. This counterexample   
   shows that it is possible for the premises of the argument to be true   
   and for the conclusion to be false. The argument has been shown to be   
   invalid. Imagination triumphs over invalidity. The argument is   
   destroyed.   
      
   The foregoing remarks illustrate the method of counterexample as it   
   applies to arguments. It is essentially a method for establishing   
   invalidity. We also have some tests for validity. If the argument is   
   in one of the valid argument forms cited above, then it is a valid   
   argument. Moreover, an argument may be shown to be valid by the   
   repeated use of the argument forms. Yet some arguments are obviously   
   valid, even though they are not in any of the argument forms   
   discussed. For example, from a statement such as   
      
   Jill is criminal lawyer.   
      
   we may obviously validly conclude   
      
   Jill is a lawyer.   
      
   Since there are valid arguments not covered by any of the argument   
   forms noted here, we need a procedure for deciding whether an argument   
   is valid. Our procedure will be as follows. We will regard an argument   
   as innocent until proven guilty. That is, we accept an argument as   
   valid until we think of some counterexample to prove that it is   
   invalid. Of course, this procedure must not be applied thoughtlessly   
   or uncritically. We must ask ourselves if it is at all possible that   
   this argument can be shown to be invalid by counterexample. We must   
   stretch our imaginations across possible worlds. If, after careful   
   reflection, we conclude that no such examples are to be found, we may   
   tentatively accept the argument as valid. This is the procedure we   
   will adopt.   
      
   EXERCISES   
      
   Find counterexamples to the following arguments. Use your imagination!   
   Remember that a valid argument may have false premises, so an example -   
   bowing a premise to be false does not constitute a counterexample   
   bowing the argument to be invalid.   
      
   1. If Smith is the thief, then Jones was involved in the crime.   
   Smith is not the thief.   
      
   Therefore   
   Jones was not involved in the crime.   
      
   2. All people apply for well-paying jobs.   
   Jane is a person who has a job she applied for.   
      
   Therefore   
   Jane has a well-paying job.   
      
   3. Social change always produces violence.   
   Violence is bad.   
      
   Therefore   
   Social change is bad.   
      
      
   [continued in next message]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)