Student or Learner
Does "more stringent ones" refer to "more stringent/serious standards"?
... if we adopt the principle of universality : if an action is right (or wrong) for others, it is right (or wrong) for us. Those who do not rise to the minimal moral level of applying to themselves the standards they apply to others—more stringent ones, in fact—plainly cannot be taken seriously when they speak of appropriateness of response; or of right and wrong, good and evil. In fact, one of the, maybe the most, elementary of moral principles is that of universality, that is, If something's right for me, it's right for you; if it's wrong for you, it's wrong for me. Any moral code that is even worth looking at has that at its core somehow.
(Please note that punctuation marks (commas, colons, semicolons, etc.) should immediately follow a word and not have a space beforehand.)