The Fallacy Of Equivocation In Republic By Socrates

At the end of Book I of Plato’s Republic, Socrates attempts to persuade Thrasymachus that the just lead a happier and more flourishing life than the unjust (354a). He argues that justice is the virtue of the soul, which allows the soul to perform its ergon, or function, with excellence. Because the soul’s function is to live, justice allows the soul to live with excellence. In this paper, I shall present and critically examine Socrates’ reasoning behind this conclusion. The argument subtly commits the fallacy of equivocation because the term function is ambiguous. I will explain my reasoning later in the paper. The argument incorrectly assumes that if the performance of the function is good, in other words the person is successful in living,

To support the first premise, Socrates uses the metaphor of a horse. He asks, “would you define the function of a horse or of anything else as that which one can do only with it or best with it?” (352e). He also defends his premise through the metaphor of the pruning knife. He states that the function of the pruning knife is to prune, because you would not be able to prune better with any other object. Thus, the knife’s function is to prune. Socrates claims that the function of a horse is that which one can do only with it or best with it. So, because the function of the horse is what a person can do best with it, the performance of its function would be judged by how well it does what the person wants it to do. Let’s say, for example, that a person wants to go horseback riding through the mountains. The horses function would be to carry the human horseback riding through the mountains. The good performance of the horse’s function, however, does not mean that it makes the horse happy, or that it is best for the horse. The same goes for the knife. Because theoretically, a person can prune best with a pruning knife, pruning is its function. It is assumed that the good performance of our function is what is good for us. The premise does not prove that if we perform our function well, we will be happy and live a good life. There will be times when being a good human being, will not be good for the human