Tutorial # 2. Why Be Moral. The Immoralist Challenge. Glaucon's Argument

Why act justly?

In the second book of the Republic, Glaucon begins by dividing goods into three categories:
1. goods that we desire for their own sake (e.g. joy);
2. goods that we like for their own sake as well as for their beneficial effects (e.g. health and knowledge);
3. goods that we desire only for their beneficial effects and not for their own sake (e.g. taking a medicine).

Being just is beneficial when others notice it and one gains a reputation for being just (as for 2.).
There can be clear disadvantages to being unjust; if others find out, it harms one's reputation, and unjust actions are likely to make one anxious that others will discover those actions (as for 3.).

What about 1.?
Glaucon's thought experiment.
He asks Socrates and Adeimantus to compare two people, one of whom is just, the other of whom is unjust.
The unjust person has a reputation for justice, despite the fact that he acts unjustly.
The just person has a reputation for being unjust that he will carry to his grave without prospect of correcting it.
Hence the unjust person will enjoy all of the benefits of a good reputation, while the just person will suffer all of the harms of a bad reputation.

Glaucon thinks that it is obvious that the life of the fortunate, unjust person is better than the life of unfortunate, just person.
Therefore justice is desirable only for its beneficial effects, and not for its own sake, and so in this respect is similar to medicine.