All knowledge, practical or otherwise, necessarily involves an element of belief a mystical foundation,

The authority of any system, Derrida insists, requires what he calls a “mystical foundation,” by which he means a founding moment of decision that could not be dictated or justified by the system it founds, a ground, then, that is itself groundless; the decision, for example, to accept science and its rationality as authoritative, the decision that leads me to begin thinking scientifically, could not itself be dictated or justified by science; it could not be based on the authority of science itself, for, precisely, it alone gives that authority its force.

Hence, from this perspective, even science requires faith, and all knowledge, practical or otherwise, necessarily involves an element of belief.