Scepticism

Scepticism is said to be an attitude of permanent doubt which does not allow for certitude but believes that definitive answers cannot be given to major philosophical problems. [Universal scepticism]

refers to doubting all knowledge; because of the limits to human knowledge, reason cannot penetrate the transcendental; transcendental knowledge may exist, but beyond sensibility and understanding (Kant). [Partial scepticism]

doubts knowledge from a particular source.