grounds of an argument; basis for reasoning
Refers to the logical foundation or evidence supporting a claim. Common in formal discussion, debate, and academic writing.
His claim lacks solid grounds.
The basis for this theory rests on multiple experimental results.
He presented the grounds for his argument.
He formulated the hypothesis based on that data as grounds.
That opinion was criticized as having weak grounds.
He countered by citing three points of evidence.
理由 is the common, everyday word for 'reason' or 'cause', while 論拠 is a more formal term stressing the logical support behind a position in an argument.
証拠 refers to concrete evidence (like a document or object) proving a fact, whereas 論拠 refers to the logical reasoning or premises supporting an argument.
論旨 means the main point or gist of an argument, while 論拠 means the grounds or evidence that support that argument, so the two 論-words are easily mixed up.
Compound of 論 (argument, discussion) and 拠 (basis, grounds). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning.