basis

base footing ground support

bed bottom foot groundwork rest seat substructure

resting place

top

assumption base essential evidence explanation footing fundamental justification premise principle proof reason security support theory

antecedent authority axiom backbone background backing bedrock cause center core crux data dictum essence heart infrastructure keynote keystone law nexus nucleus postulate presumption presupposition root rudiment sanction source substratum theorem warrant

chief ingredient hard fact principal element underpinning

auxiliary fact reality trivia

effect end exterior exteriority outside periphery result surface