>>ukchristian28
The point is that an atheist has no objective moral standard by which to determine what is right or wrong, and that in a random, meaningless, godless universe there is not really any reason to hold any moral viewpoints. An atheist may hold moral viewpoints, but they do so inconsistently with their worldview. That was my argument. <<
You aren't using the word "inconsistent" correctly. In logic, a theory is consistent if it contains no contradictions.
Consider an atheist who accepts these assumptions: "increasing human suffering is wrong" and "killing humans increases human suffering". From these, they can quite consistently come to the conclusion that "killing humans is wrong" and condemn terrorism and murder. Additional assumptions are necessary to derive higher-order caveats, such as self-defense and protection of others.
Now, you may argue with either or both of the assumptions above, but there is no inconsistency in this bit of logic.
Since your argument, and Blanchard's, relied on the _logic_ being flawed, rather than the _assumptions_, it is invalid.
Logically speaking:
Let [they can logically derive a prohibition on killing humans from their assumptions] = A and [their worldview is inconsistent] = B.
You appear to argue: If NOT A, THEN B.
We have shown A. Therefore, B cannot be logically inferred, and your argument is wrong.
Note: B cannot be logically excluded either - which is fine, since no system of logic sufficiently complicated to reflect reality can be proved to be consistent.
Everyone's worldview is inconsistent at some point. This is not a bad thing: finding an inconsistency gives us the opportunity to learn something, and re-think our assumptions.