In Book I of The Republic, Socrates uses a craft analogy (CA) as part of his argument against Thrasymachus to convince him that justice is not the advantage of the stronger. To do so he equates ruling to a craft. Crafts tend to a certain domain (e.g., doctor), and their purpose is to make the objects of their domain better (e.g., patients). From this he concludes that "no one in any position of rule, insofar as he is a ruler, seeks or orders what is advantageous to himself, but what is advantageous to his subjects; the ones of whom he is himself the craftsman."
This seemed like a big jump to me, which entails some underlying premises which are not made explicit as part of the argument. Robert Coltert specifies these underlying premises as such:
- First, it presupposes that the virtues [in this case, justice] are analogous to the crafts in all salient aspects.
- The second assumption is that all crafts have the same structure and are analogous to one another.
If these assumptions do not hold, then the use of the CA as a method of refutation is called into question because various crafts might have different structures and a definition of virtue need not make that virtue be analogous to every craft, and thus the CA is not a reliable method of investigation.
Furthermore, a bigger problem with the CA arises further in the argument when Socrates claims wage-earning is an auxiliary craft other crafts rely on:
If wage-earning is a craft - and Socrates calls it one at 346c - then wage-earning is itself a counterexample to the claim that no craft benefits its practitioner. The benefit provided by wage-earning is the wages that the practitioner receives.
These two underlying premises seem quite far-stretched to me, and I was surprised they were not given any further attention as part of the dialogue in Book I.
- What are some arguments for these underlying premises to be true?
- Does Socrates or later philosophers discuss this exact issue elsewhere? I only found the discussion by Robert Coltert, thus do not known how widespread this concern is.