A sophist is someone who makes good points about an issue — until you realize those points aren't entirely true, like a political candidate who twists an opponent's words or gives misleading facts during a speech.
Sophist has the accent on the first syllable: "SAW fist." It comes from the Greek word sophizesthai, meaning "to become wise or learned, deceive." In fact, deceit was just part of the job for the ancient Greek philosophers called Sophists. The cleverness of the Sophists prevented students from seeing that the Sophists' arguments didn't reach logical conclusions — and the Sophists kept their paying students coming back for more.