Taxonomy of the Potential Parts of Justice

As explained elsewhere, the potential parts of a cardinal virtue participate in that virtue while falling short of satisfying its complete definition. Justice, strictly speaking, is a virtue by which we render others their lawful due according to equality, so that failure to do so is a fitting matter for litigation and punishment in the eyes of those who care for the good of the relevant community.

Consequently, all the potential parts of justice are similar to the principal virtue in having to do with our treatment of others. However, they fall short of satisfying the complete definition of justice in either one of two ways:

  • with respect to equality: This occurs when the person or persons to whom we owe something are such they we cannot render them their due according to equality. That is, we cannot give back to them anything close to equal what they have given us by virtue of their generosity, example, guidance, etc. There are three potential parts of justice that fall under this category:
    • religion (religio), which is the virtue by which we honor God directly by appropriate interior and exterior acts.
    • piety (pietas), which is the virtue by which we honor our parents and our homeland.
    • respect (observantia), which is the virtue by which we render honor (dulia) and obedience (obedientia) to those who are our superiors because of their virtue or because of their office.

  • with respect to lawful due: Here St. Thomas distinguishes lawful due (debitum legale), which is the object of justice proper, from moral due (debitum morale), which has to do with the rectitude of virtue.
    • The relevant moral due is required to such a degree that virtue is well-nigh impossible without it:
      • What one owes to others, absolutely speaking: Truthfulness (honesty) in self-representation.
      • What one owes to others by way of compensation for things done to one: Gratitude for good things and vindication (punishment) for bad things.

    • The relevant moral due is conducive to, but not absolutely required for, virtue: Liberality, friendliness, etc. (How about niceness or pleasantness, which often impresses us more than moral rectitude?)