Someone skilled in dialectics: someone able to arrive at logical conclusions through reasoned argument.
Someone skilled in dialectical materialism: someone able to arrive at socio-political conclusions through consideration of class differences.
Someone knowledgable about dialects.
Someone skilled in dialectical idealism: someone able to arrive at historical conclusions through consideration of contradictions.
A teacher who uses plausible but fallacious reasoning.
One of a class of teachers of rhetoric, philosophy, and politics in ancient Greece.
One who is captious, fallacious, or deceptive in argument.