Theories, models and structures: thirty years on

Thirty years after the conference that gave rise to The Structure of Scientific Theories, there is renewed interest in the nature of theories and models. However, certain crucial issues from thirty years ago are reprised in current discussions; specifically: whether the diversity of models in the science can be captured by some unitary account; and whether the temporal dimension of scientific practice can be represented by such an account. After reviewing recent developments we suggest that these issues can be accommodated within the partial structures formulation of the semantic or model-theoretic approach

Sacrifice and Efficiency of the Income Tax Schedule

We investigate the efficiency of equal sacrifice tax schedules in an economywhich primitives are exactly those in Mirrlees (1971): a continuum of individualswith identical preferences defined over consumption and leisure who differ withrespect to their labor market productivity. Using a separable specification forpreferences we derive the minimum equal sacrifice allocation and recover thetax schedule that implements it. The separable specification allows us to usethe methodology developed by Werning (2007b) to check whether the scheduleis efficient, that is, whether there is no alternative tax schedule that raises morerevenue while delivering less utility to no one. We find that inefficiency does notarise for most parametrizations we use to approximate the US economy. For thefew cases for which inefficiency does arise, it does so only for very high levels ofincome and marginal tax rates.