Practical arguments for theoretical theses

Pascal's wager is expounded as a paradigm case of a practical, decision-theoretical argument for acting as if a proposition is true when we have no theoretical reasons to accept or reject it (1.1.-1.2.). Though the paradigm is fallacious in various respects there are valid and adequate arguments for acting as if certain propositions are true: that theoretical entities exist, that there are material perceptual objects, that the world is uniform across time (1.3). After this analysis of examples the author's general approach for developing criteria for the validity and adequacy of types of argument (2.1.) is applied: Having discussed some problems (2.2.-2.3.), a general epistemic principle for such "pascal arguments" is developed, which characterizes their premisses and, if introduced as an additional premiss, can make them deductively valid (2.4).