logician

n. one who studies logic; one who is skilled at reasoning

Logic (from Classical Greek λόγος logos; meaning word, thought, idea, argument, account, reason, or principle) is the study of the principles and criteria of valid inference and demonstration.As a formal science, logic investigates and classifies the structure of statements and arguments, both through the study of formal systems of inference and through the study of arguments in natural language. The field of logic ranges from core topics such as the study of fallacies and paradoxes, to specialized analysis of reasoning using probability and to arguments involving causality. Logic is also commonly used today in argumentation theory.
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Noun
1. a person skilled at symbolic logic
(synonym) logistician
(hypernym) expert
(hyponym) dialectician

(n.)
A person skilled in logic.
  

logician