Argument from Conscience

[TheRealJoeFish]

Two big logical issues occur to me within 5 seconds:

1) Obligated by what? I actually don't think this is fatal, or really all that important.

2) The equivocation of "obligated" (in 1) and "morally obligated" (in 3). That's a big, big jump. Even if premise 1 is true, premise 3 is a non sequitur, and thus the conclusion fails unless we define "moral obligation" (and assume or prove it exists). I am 99% certain this will collapse into the argument over whether there is a source of morality external to humans. Of course, when that collapse occurs, the argument becomes circular: 6) there is an external source of conscience ONLY IF (additional premise) there is an external source of morality. That statement's vacuous.

Essentially, I think this argument is logically equivalent to the question of external morality, an issue that has been discussed ad nauseum here.