The objective of this paper is to identify factors that may lie behind the tendency for parliamentary governments to be composed primarily from one side of the left-right spectrum and to adopt correspondingly non-centrist policy positions, i.e. to be non-congruent with median voter opinion. Because many factors may combine to translate voter preferences into governmental outcomes and because some of them lack real-world variability or measurability, their roles are explored here through simulation experiments. The new software that has been created for these experiments allows a wide variety of potential factors, including voter and party motivations and distributions, policy space dimensionality, and constraints on government formation, to be manipulated in order to explore possible causal effects. Wherever possible, the simulations specify parameters that resemble their real-world equivalents or at least that vary in ways that allowed their potential effects to be assessed. Although the outcomes of these experiments cannot tell us what actually fosters non-centrism in the real world, they do reveal some of the factors that appear to be conducive to that end and thus serve as a guide to further research on this neglected topic.
