Dialogue
The primary method of Socratic verbal and Platonic written philosophy, based upon a conversational posing of and response to questions about any given matter or concept. Though at times almost painfully methodical, the presentation of ideas in dialogue form creates at least an impression of increased philosophical legitimacy, since the treatment of a topic (even if fictional) moves forward only with agreement among the multiple participants regarding the argument's prior steps. In contrast to the false art rhetoric, Socrates (and through him Plato) argues dialogue to be the only reliable method of philosophical inquiry. This is so since it takes into account a democracy of multiple perspectives, unlike the dominant tyranny of rhetoric.
Plato often quite cleverly uses the dialogue structure to the great advantage of his various arguments. For example, he frequently has one of the more minor characters in a discussion profusely agree with Socrates's every inquiry, which serves to reinforce the points to which he assents in the mind of the reader. Or again, rather than undercutting the force of his points, Plato uses the disagreement with Socrates of any of the other characters to introduce ever newer perspectives and objections, the subsequent answering of which pushes the dialogue into ever newer territory for consideration. This device presents a perfect opportunity for the advancement of whichever claims Plato desires.
Elenchus
The elenchus is the primary method of Socratic philosophy. Essentially a cross-examination, it proceeds by an intensive series of questions and aims to lead the interviewee to conclude for himself that he does not know what he assumed to know previously. The elenchus is Socrates's primary means of deepening the wisdom of his students. By convincing other characters in an elenchus that they do not actually know the nature of something they thought they did, Socrates brings these characters closer to one single truth and grain of knowledge—namely, that they know nothing.
Socratic Irony
Socratic irony is a form of indirect communication employed by Socrates to reveal the ignorance of his interlocutors while insincerely praising their abilities. This technique is deeply informed by the elenchus. Socrates even occasionally practices it against himself although scholars today are divided as to his sincerity while doing so.
Knowledge
According to Plato, knowledge can only pertain to eternal, unchanging truths. I can know, for instance that two plus two equals four, because this will also be the case. I cannot know, however, that someone is beautiful. For this reason, only the intelligible realm, the realm of the Forms can be the object of knowledge.
The “divine sign”
A little voice in Socrates’ head that often warns him not to do things that could be of great danger to him. That, for instance, is why he has always stayed away from politics, having been warned by his divine sign that he would meet with trouble.
Impasse
An instance in Plato’s early dialogues where the interlocutor is made to realize that they do not understand what they claim to know, and in which no positive definition is given.