Viability

Of organisms: likely to live, likely to propagate genes;

of theories or hypotheses: likely to withstand stringent empirical tests;

more generally: practicable or worthwhile, e.g., of an alternative strategy, etc.

(see also: the principle of Natural Selection, Darwinism, Evolution, Genetic Recombination, Mutation, science, scientific approach, scientific methodology, pseudo-science. construct, verification, implication, systematic evidence, anecdotal evidence, (conceptual) models, operational definition, critical thinking, falsifiability, testability)