Full Idea
Sentence are held to be basic because they are self-evident or 'cataleptic' (Stoics), or rooted in sense data (positivists), or grasped by intuition (Platonists), or revealed by God, or grasped by faculties certified by God (Descartes).
Gist of Idea
Basic beliefs are self-evident, or sensual, or intuitive, or revealed, or guaranteed
Source
J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.01)
Book Reference
Baggini,J and Fosl,P.S.: 'The Philosopher's Toolkit' [Blackwells 2003], p.5
A Reaction
These are a bit blurred. Isn't intuition self-evident? Isn't divine guarantee a type of revelation? How about reason, experience or authority?