Now I'm sure that Peart reflected, when using the term "moral compass", that a compass works by magnetism. It is a device whose only purpose is to visually orient a consciousness to the location of an unseen force. In the case of the compass, a magnetic material is free of physical forces and finds its most stable position oriented toward the magnetic poles of the planet.
This is a curious analogy for Peart to make. Does he imply that his sense of morality is, like the compass, aligned to forces external to himself. It seems so, though Peart's lines leave some ambiguity:
"I've got my own moral compass to steer by
A guiding star beats a spirit in the sky"
[Faithless, Snakes & Arrows, 2007]
It seems clear that he uses "beats" in the sense of "wins over" or "trumps", rather than beats as in rhythm. So in this couplet, Peart seems to be saying that his moral compass is aligned toward "a guiding star" rather than a "spirit in the sky," the latter being a derogatory reference to a deist or pagan concept of an impersonal god.
This is a slightly mixed navigational metaphor; one would normally presume that the Polestar and the Magnetic Pole were two different entities, where Peart seems to use them as one. But we'll allow him poetic license and trudge on. I think it's safe to presume, knowing Peart's enthusiasm for rationalism, that by "guiding star", he means philosophic principles. Note that it is possible to be less generous, and presume that Peart is referring to astrology. It would have been unthinkable to do so just a few years ago, but he seems to have fallen into Tarot-reading, and it is not beyond the pale to construe that Peart (in his "scientific guise") believes that the subtle gravitational influences in the position of stars somehow affect the psychology and behavior of humans. If the latter is the case, I'm sure that Peart would find it disconcerting to see the evidence that the position of chairs in the room in which one is born have more gravitational influence than the position of stars. Nevertheless, we should give him the benefit of the doubt and use the more generous interpretation.
The key aspect of this couplet is that Peart is derogatory toward the "spirit in the sky", but recognizes that there is an objective entity outside of himself that his "moral compass" responds to. This is critical, for it is a distinct challenge to the philosphic relativism that permeates much of his work. Still, without reference to this external entity, Peart is left with the problem that a subjective moral compass is neither moral nor a compass. The aforementioned Cho Seung-Hui is evidence that conscience cannot be used as a standard for social behavior. When one casts aside all objective (extrinsic) morality, one is left unable to make any value judgments whatsoever. Which would be anathema to Peart, who is one rolling lump of value judgments. It is positive that he recognizes something objective and external.
Later in "Faithless" we see another metaphor:
"I've got my own spirit level for balance
To tell if my choice is leading up or down"
[Faithless, Snakes & Arrows, 2007]
Again, we see a reference to an external, objective standard in "up or down." But now the term "spirit" is used in a positive sense, something like "incorporeal." This seems trivial, but it is a key theme in Peartism. "Spirit" is OK if it is pagan or gnostic, but it is worthy of mockery if it becomes personalized. It becomes easier to picture Peart as a Manichee.
Proceeding with this same verse, Peart continues:
"And all the shouting voices
Try to throw me off course
Some by sermons, some by force"
Aside from the need to rhyme, I'm not sure why Peart would indicate that someone is forcing him to go in a direction counter to that indicated by his "spirit level." But in any case, whether by argument or force, apparently EVERY SHOUTING VOICE is running counter to the objective, external force that Peart's internal meter is responding to. This seems curious. It is almost as if Peart were arguing that any effort to communicate between human beings with regard to the moral choices another human is making is, by the nature of communication, rendered contrary to the correct, external, objective moral direction. Otherwise, only SOME shouting voices would be trying to steer him off course, while other shouting voices would be aligned with that correct direction. Unless one allows for the idea that Peart is not referring to an external, objective moral direction at all, but instead to some sort of self-defined axis. Now we reach the height of absurdity, for if Peart is saying that his "spirit level" is a meter that aligns to himself, then it's only use would be to tell him when he was arbitrarily veering from an arbitrary course.
We must allow another possibility, and that is that Peart is only referring to shouting voices that are encouraging a direction contrary to the external, objective moral direction. In such a case, it is perfectly all right for people to communicate moral judgments, provided they share the reference to the external, objective moral direction.
In summary, Peart's very question of morality raises the dilemma for his relativist "tolerate everything" secular humanist view. He cannot even converse about the issue, or support his argument, without the use of metaphors that demand external, objective moral directions. And yet he provides no answer as to what constitutes the objective authority of those moral directions, and he makes every effort to distance himself from any objective authority, decrying in the absolute sense the voices of authority who make their one appearance in his song.
I wish we were done here so that we could move on to the fertile ground of "The Way The Wind Blows", but alas, there is more gold to be panned from this stream...