A person who doubts; someone who is inclined to question or disbelieve.
Formed from 'doubt' plus the agent suffix '-er' (from Old English 'ere,' meaning 'one who does'). The same pattern creates words like 'teacher,' 'runner,' and 'believer.' This word has been used since at least the 16th century.
Famous 'doubters' in history—like Thomas in the Bible (hence 'Doubting Thomas') or David Hume in philosophy—actually advanced human knowledge more than blind believers, because skepticism drives us to ask better questions and demand evidence.
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