Metaphysical commitment is unavoidable. Every person assumes some metaphysical stance or other, tacitly or expressly, whether or not he is conscious of assuming it. That is to say: he takes something or other to be ultimate or absolute or foundational or finally authoritative. For some this is God, but for others it is “humanity, the nation, the individual, historical development, or even life as life for its own sake, in its complete emptiness and mere dynamic.”

Secularization is the process whereby God is replaced by some such mundane ersatz. But the replacement of God by the individual, say, or by the revolution, does not alter the fact that something is being taken as absolute, as an ultimate focus and locus of meaning. The only question is whether this is something transcendent or something immanent (worldly).

Someone who attempts to reject every absolute soon finds himself affirming one willy-nilly. To say, “I accept nothing whatsoever as absolute!” is to accept as absolute the rejection all absolutes. After all, a relativized rejection of all absolutes would be one that countenances circumstances in which absolutes would be affirmed. To claim that all is a matter of perception or perspective, that there are no absolute truths or absolute moral standards, is to posit some principle of perspectivism or relativism as an absolute principle. A relativized or perspectivized perspectivism undercuts itself.

—  Bill Vallicella.  Not a presuppositionalist from what I can tell, but apparently a devotee of this insight of Van Til’s.