Plato creates a seemingly invincible philosopher in The Republic. Socrates is able to refute all arguments presented before him with ease. The discussion on justice in Book I of The Republic is one such example. Socrates successfully refutes each different view of justice presented by Cephalus, Polemarchus, and Thrasymachus. Socrates has not given us a definitive definition of justice, nor has he refuted all views of justice, but as far as we are concerned in Book I, he is able to break down the arguments of his companions.
Cephalus is the first to give his opinion of justice as simply "speaking the truth and giving back what one takes." In even simpler terms, it is to do the right thing. (Republic 331) Socrates argues that to give a borrowed weapon back to a friend that has become insane is not justice but injustice. Cephalus concedes that his definition of justice is flawed and leaves.
From Polemarchus we learn that justice is "giving each his due" as he quotes from Simonides. After some debate, Socrates and Polemarchus conclude that this definition can be refined into helping your friends and harming your enemies. Socrates is able to reduce this view of justice to injustice by reasoning that it is never just to harm anyone, friend or foe.
Justice is the advantage of the stronger according to Thrasymachus. He even goes a step farther to say that injustice is stronger and freer than justice, yet justice is the advantage of the stronger. Socrates shows that justice is in the receiver of it, not the provider. According to Socrates, a just man will be the healthier and happier man because he is wiser.
So it is not a question of Socrates refuting the views presented to him by these three men, but one of the completeness of these views. Does Plato give each of these views a proper defense, or is he trying to build up his glorified version of Socrates? Cephalus is not given much exposure in Book I so his argument on justice is somewhat limited. But for Socrates, refuting a statement as simple as giving back what one takes does not take...