A Short Course in Logic

Evaluating Arguments -

An argument is successful if it meets the following conditions:
1.  All of its premises are true.
2.  The premises provide sufficient support to the conclusion.
3.  There are no true statements that, if added to the premises, would
    result in an expanded argument in which the premises do not
    support the conclusion.

One type of successful argument is a sound (deductive) argument.

An argument is a sound (deductive) argument if it meets the following
conditions:
1.  All of its premises are true.
2.  The argument is valid.

An argument is valid if it is inconceivable that its premises are all true
while, at the same time, its conclusion is false.

Example of a valid argument -
      
     All students at Michigan Tech were born in Michigan.
     Some astronauts are students at Michigan Tech.
     Therefore, some astronauts were born in Michigan.

(Although the above argument is valid, it is not sound since at least one
of its premises is false.)

Important principles:
  The conclusion of any sound (deductive) argument is true.
  We should accept the conclusion of any successful argument.


ETHICAL RELATIVISM - PRO AND CON

Argument for ethical relativism -

1.  Different societies subscribe to different sets of moral values.
2.  There is no possible moral authority other than the moral code of
    one's own society.
3.  Therefore, ethical relativism is true.

Another argument for ethical relativism -

1.  In at least some instances, whether one has a certain moral
    obligation (e.g., to care for one's maternal aunts and uncles in their
    old age) depends on the moral values of one's society.
2.  According to ethical relativism, whether one has a certain moral
    obligation depends on the moral values of one's society.
3.  Therefore, ethical relativism is true.

Argument against ethical relativism -

1.  If ethical relativism is true, then the moral codes of different
    societies are all equally valid.
2.  A society whose moral code sanctioned the random torture of
    children would have a "bad" moral code.
3.  Therefore, ethical relativism is not true.