The Synopsis of Major Arguments (from Russ Shafer-Landau's Whatever Happened to Good and Evil?  New York: Oxford University Press, 2004, pp. 137 ff.

The Argument from Freedom of Conscience and Expression:
  1. If people possess equal rights to an opinion about X, then their opinions about X are equally plausible.
  2. People possess equal rights to an opinion about morality.
  3. Therefore, people's views about morality are all equally plausible.
    • Error: First premise is false: while I have a right to an opinion about the relativity of time and space, you'd still be better off reading Einstein or Hawkins.
The Argument from Tolerance:
  • First Version:
    1. If moral skepticism is true, then we must be tolerant.
    2. Moral skepticism is true.
    3. Therefore, we must be tolerant.
  • Second Version:
    1. If tolerance is valuable, the skepticism is true.
    2. Tolerance is valuable.
    3. Therefore, skepticism is true.
  • Error: If skepticism is correct, then any moral demand--including the demand for tolerance--is in question.  And so, if skepticism is correct, tolerance is not required.
The Proof that Everything follows from a Contradiction:
  1. A is true and A is false.
  2. Therefore, A is true.
  3. Therefore, either A is true or B is true.
  4. A is false.
  5. Therefore, B is true--where "B" may be anything and everything under the sun or under anything else.
The Argument from Global Skepticism:
  1. If global skepticism  (nihilism) is true, then moral skepticism is true.
  2. Global skepticism is true.
  3. Therefore, moral skepticism is true.
    • Error: Nihilism is self-refuting.  Asserting that there is no such thing as values, nihilism is shown to be false if there is at least one person or group who do hold values of any sort.
Modus Tollens and Modus Ponens:
  • Modus Tollens:
    1. If p is true, then q is true.
    2. q is false.
    3. Therefore, p is false.
  • Modus Ponens:
    1. If p is true, then q is true.
    2. p is true.
    3. Therefore, q is true.
  • Note that variants of these two arguments where either the consequent is affirmed or the antecedent denied are not valid, being referred to as the fallacy of denying the antecedent and as the fallacy of affirming the consequent.
The Argument from Disagreement::
  1. If well-informed, open-minded people intractably disagree about some claim, then that claim cannot be objectively true.
  2. Well-informed, open-minded people intractably disagree about all ethical claims.
  3. Therefore, there are no objective ethical truths.
    • Error: Intractable disagreements can happen in all fields of human exploration.  Certainly, several well-informed and open-minded people  seem to disagree intractably about string theory, the nature of global warming, the existence of a god, and so on--without concluding that an objective truth is not to be found.
The Argument from Atheism:
  1. Ethics is objective only if God exists.
  2. God does not exist.
  3. Therefore, ethics is not objective (and anything goes).
    • Errors:
      1. Theists should reject the first premise because the natural justification for the Divine-Command Theory is problematic, primarily because it yields a conception of God as an arbitrary being whose choices are unsupported by reason.
      2. Atheists should reject the first premise because they have, as they see it, examples of other laws (mathematic laws, logical laws, physical laws) whose objectivity does not rest on divine authority.
      3. Theists will reject the second premise and claim that without further argument, the second premise begs the question--that is, people who say that God does not exist already make the assumption of non-existence since no one can prove a negative.  This does not by default show that God does exist, by the way.  The onus of proof is always on the claimant and so the onus of proof of the existence of one or several gods is on the believer, not on the non-believer.
The Argument from Occam's Razor:
  1. We have reason to believe that something exists only if it is explanatorily indispensable.
  2. Moral facts are not explanatorily indispensable.
  3. Therefore, we lack reason to believe in the existence of moral facts.
    • Self-Referential Error:  These truths are normative and guide us; they do not have existential status in the world.  If there were no such truths, Occam's Razor--being a normative truth of that sort--would not be possible either.
The Argument from Certainty:
  1. Knowledge requires certainty.
  2. We can never be certain of the truth of our moral beliefs.
  3. Therefore, we cannot have moral knowledge.
    • Error: If this were a sound conclusion, human knowledge as a whole would be impossible.  Even for protocol statements, one can adduce sufficiently succinct doubt to raise uncertainty.
The Epistemic Argument from Disagreement:
  1. If well-informed, open-minded people intractably disagree about some claim, then we cannot know whether that claim is true.
  2. Well-informed, open-minded people intractably disagree about all moral claims.
  3. Therefore, there can be no moral knowledge.
    • Error: The first premise is false: A failure to convince intelligent opponents does not necessarily undermine one's own views.  At the same token, one's own views are not necessarily unchallengeable by that observation.  The point is that by the disagreement of intelligent people, our knowledge advances.  We do not need certainty and global agreement to gain new insights.
The Perspectival Argument:
  1. We are able to gain knowledge only if our beliefs are formed from within the best perspective for judging the matter at hand.
  2. There is no perspective from which to judge moral matters.
  3. Therefore, we cannot have any moral knowledge.
    • Error: (1) and (2) contradict each other. If (2) is true, then (1) must be false, for there is also no one and only perspective for any other endeavor such as physics or philosophy, for example.  And if (2) is false and we can indeed have such a perspective when we try to rid ourselves of prejudice or self-directed interests and so on, then (1) is true, for there may be several best perspectives by which we judge matters indeed.
The Regress Argument:
  1. If a moral belief is justified, then either (i) the moral belief is self-evident, or (ii) it is justified by another belief.
    • (i) is impossible: there are no self-evident moral beliefs: this would violate Hume's "is-ought" thesis.
    • (ii) is impossible: moral beliefs cannot be justified by other beliefs.
  2. Moral beliefs cannot be justified by non-moral beliefs: this would violate Hume's "is-ought" thesis.
  3. Moral beliefs cannot be justified by other moral beliefs: this would land us in an infinite regress.
  4. Therefore, there are no justified moral beliefs.
  5. Therefore, there is no moral knowledge.
    • Errors: If the argument is sound, then it can be generalized to cover every area of knowledge. 
    • (1) may be mistaken. Beliefs may be justified by things other than beliefs--specifically by the fact that they have been reliably produced.
    • (2) may be mistaken: there may be self-evident moral beliefs.
    • (3) may be mistaken: coherentists claim that a belief's being situated in a coherent network of beliefs, which confer support on the belief in question and which in turn derive support from it, is enough to render a belief justified. 
The Argument from Rationality:
  1. If you are morally obligated to do something, then you have good reason to do it.
  2. If you have good reason to do something, then doing it must further what is important to you.
  3. Therefore, if you are morally obligated to do something, then doing it must further what is important to you.
  4. What is important to you is subjective matter, fixed by personal choice.
  5. Therefore, all of your moral obligations are fixed subjectively.
    • Errors: Though some objectivists bite the bullet and abandon (1) and others, following Plato's lead, are willing to give up (4), one might also think that (2) is false.  Our reasons may indeed extend beyond what matters to us personally.  We do favor aiding others even if there is nothing in it for us.
Dr. Reinhold Schlieper
December 8, 2003