I have recently developed two kinds of model for inductive logic with causal modalities, the deterministic and the probabilistic. Roughly speaking, the first provides certain syntactic and semantic criteria for causal necessity, so that a causal or nomic universal can be deductively derived from a certain actual universal; whereas the second model allows only a probabilistic transition from actual universality to causal universality. These models are meant to provide, from a modal point of view, a formal explication of nomic universality both in its semantic and inductive aspects.

However, these models are too abstract if we want to treat adequately such problems as causality, the confirmability of causal laws, etc., in that they do not have a framework of space and time, which seems essential to our conception of causality.