In Crito, Socrates argues against Crito, saying that he should not accept Crito's help in escaping from prison to avoid the death penalty that has been decreed. Socrates is under the death penalty for what the authorities see as his attempt to corrupt the young with his dialogues, a charge of impiety against the state. Basically, Socrates argues that the individual has a higher duty to the truth, to justice, to goodness, and to the city, than he does to the instinct to survive, or to friends and family.
Crito's arguments are emotional and not grounded in the reason upon which Socrates has based his whole life. Socrates is saying that he has honored reason and its use as a tool to find the truth and expose lies all his life. If he were to turn his back on reason, and follow Crito's emotional call to flee to live and be with his friends and family, he would be betraying every value and principle thing for which he stood his whole life.
Socrates' arguments against Crito's suggestions are indeed consistent with his other teachings. In fact, that is the whole point that Socrates is trying to make--namely, that he must be consistent in his adherence to the truth, justice, etc., if his words and life are to have any meaning and worth. Socrates is basically saying that he must show by his action--staying and facing the hemlock--that he means what he has said his entire life. Were he to run, to escape, to live a life outside of the law, he would be showing that his life prior to that time had been a lie. It is consistency in his life and in his teaching that he strives for, not for the sake of consistency alone, but for the sake of the truth which he strives to faithfully and consistently serve.
The central principle in Socrates' argument (that he must accept the death penalty rather than escape) is the principle that one follows through when one gives one's word. To Socrates, he has entered into an agreement with the city by liv...