How many letters does the top answer for “your basis for belief or disbelief; knowledge on which to base belief” have?

The most common answer is evidence (8 letters).

Crossword clue: your basis for belief or disbelief; knowledge on which to base belief

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

evidence 8 letters wn-def

your basis for belief or disbelief; knowledge on which to base belief

grounds 7 letters wn-def

your basis for belief or disbelief; knowledge on which to base belief