Rationalisation or Justification?

I've previously pursued one form of epistemic scepticism about morals. Here's another, more limited case.

When one acts, one usually has some justification in mind. "I just made a cup of coffee because I was thirsty and needed to wake up". Sometimes though, one is fooled, and rationalises rather than justifies. "I just got angry because it is better that Bloggs realises that his actions were inappropriate". Here, what is offered is meant to be a justification, but more impartial observers can sometimes spot that the action was really bad, and the speaker has simply generously ascribed better motives onto themselves than they really had.

But the problem is that such rationalisations can really be convincing. I know that I've been certain that I did something for a certain reason, and only years later realised that I was covering up my own faults by pretending that they were well-planned right actions. If right actions are indistinguishable from rationalisations, then perhaps one rarely knows whether oneself is acting for good reasons or not.

Now, you might think that this scepticism is very limited in application, since others can usually spot the difference between justification and rationalisation. But it's possible to worry that some common justifications are actually rationalisations of universal, but negative, human traits. To take an example (and no more than that without appropriate evidence to support it), perhaps beliefs about how morality cannot demand that people in the western world give most of their savings away in aid to the third world are simply post-hoc rationalisations of the fact that we're terrible at actually being quite so charitable.

Now this particular example isn't the point. The point is that the possibility of rationalisation might undermine our faith that we are justified in vast swathes of the moral judgements that we make. That's worrying.