How are Plato's four cardinal virtues to be translated to the present day?
'Cardinal' comes from Latin 'cardo' for 'hinge'; 'virtue' is from Latin 'virtus', literally 'manliness', the translation of Greek _aretae_, signifying 'excellence', 'goodness', 'competence', 'proficiency'. Hence virtue traditionally concerned the manly excellence of men. Today this narrow focus has been widened.
i) _phronaesis_ (understanding) is the ability to understand the world from within an historical-hermeneutic cast of being, through which occurrents* of all kinds present themselves AS what and who they are to the mind in any occurring situation, thus fulfilling a necessary precondition for prudent action.
ii) _sophrosynae_ (temperance, literally, the rescue of _phronaesis_, of understanding) is the ability to temper your desires so that prudent understanding is not overwhelmed by desire in your actions. Desire (_epithymia_) of whatever kind (e.g. lust, greed, ambition) needs to be restrained.
iii) _andreia_ (literally, manliness, courageousness) implies the firmness to take a stand, showing your self to the world, and the courage to risk your own life-movements in engaging with the world, especially with the others in your world.
iv) _dikaiosynae_ (justice) is fairness in the interplay with others in the world. Such fairness consists in mutually estimating and esteeming each other's abilities and powers as well as all their exercise has acquired. 'Fair' is to be understood here also as _to kalon_, the beautiful, the opposite of _to aischron_, the ugly and shameful. Who people are and what they have must be duly estimated in the interplay for it to be fair.
Achieving excellence 'hinges' on these four aspects when leading your life in the world. Since all living is a kind of movement, and all movement is a power (_dynamis_) of some kind at work (_en toi ergoi_, _energeiai_, energy), all engagement with the world is a power play with other occurrents, both things and people, i.e. both whats and whos.
Hence justice is fairness in the mutual exercise of powers and abilities in engaging with others in the world, and courageousness is the power to resist adverse counter-powers and to take a risk with your own powers and abilities, guided by sound understanding with tempered desire. Such power interplay can become fair or ugly, however. It becomes ugly especially when (one or some of) the players do not keep their desires in check, but instead give them free rein, thus deploying their own powers to cheat one way or the other in the power plays. Power plays are of their nature unpredictable, with endless possible situational configurations, moves and counter-moves. Hence they elude all efforts of the will to effective power to control them.
* 'Occurrents' is introduced here as an alternative to 'beings', 'entitiies', signifying all that presences and absences within the three-dimensional clearing of time, whether sensuously or not. The mind and the time-clearing are two sides of the same coin.
Further reading: Social Ontology.