Socrates vs Thrasymachus

Any argument relies upon some fundamental agreement about the issue being discussed. However great the divide in opinion may be, there must exist at least some similarity in the participants’ manner of viewing the issue if a solution is ever to be reached. Book One of Plato’s Republic features a disagreement between Socrates and Thrasymachus about the nature of justice. The disaccord between their views of the subject is extremely pronounced, but there are certain underlying agreements which guide the course of the debate. One way to evaluate the validity of the arguments involved is to examine whether the assumptions at the root of the argument are in accord with this common ground. By my reading of the dialogue, Socrates’ reply to the first part of Thrasymachus’ definition of justice rests safely upon this common ground, whereas his answer to Thrasymachus’ second definition moves away from this mutually acceptable base, and is injured as a result. In exploring this topic, I intend to examine briefly Thrasymachus’ two-part definition of justice. For each of these parts I will evaluate one Socratic response and discuss it from the perspective of the “craftsman analogy” – an analogy which is initially used by common consent, but which Socrates adapts until its original usage almost disappears.

Thrasymachus’ first definition of justice is easy to state, but it is not so immediately clear how it is to be interpreted. Justice, he claims, is the advantage of the stronger. On its own, such a sentence could imply that what is beneficial to the stronger is just for and therefore, beneficial to the weaker, and Socrates accordingly asks whether this understanding is accurate. Thrasymachus promptly responds in the negative. The interpretation he proceeds to expound upon can be summed up by adapting slightly his original definition: justice is that which obtains the advantage of the stronger. To support this definition, he points to the example of ruling a city. Any ruling