However, Clark allowed that presupposing axioms (or "first principles") themselves do not make a philosophical system true, including his own; the fact that all worldviews he examined other than Christianity had internal contradictions only made Christianity highly more probable as truth, but not necessarily so. Nonetheless, he believed that this method was effective in many practical cases (when arguing against, for instance, secular humanism or dialectical materialism) and that, in the end, each of us must simply choose (that is, make an informed selection) from among seemingly consistent worldviews the one that most adequately answers life's questions and seems the most internally coherent. Some Van Tillian critics suggest that the concept of coherence itself must be defined in terms of Christian presuppositions but is instead being used by Clark as a "neutral" principle for discerning the truth of any proposition.