René Descartes

Can someone reasonably accept parts of David Lewis’s modal realism without accepting all of it? Which parts can be separately accepted?

It is a profound question indeed, whether one can, in good conscience, accept only certain aspects of David Lewis's modal realism while rejecting others. In contemplating this query, one must consider the nature of modal realism itself, which posits the existence of possible worlds as ontologically on par with our own. Lewis asserts that these possible worlds are not merely abstract entities, but concrete realities in their own right, containing their own inhabitants, laws of physics, and so forth. This view challenges our conventional understanding of reality, urging us to expand our conceptual framework and embrace the vast array of alternative worlds that may exist alongside our own. However, one may find certain aspects of Lewis's modal realism to be more palatable than others. For instance, one could accept the idea of possible worlds as abstract representations of alternative states of affairs, without subscribing to the notion that these worlds possess the same concrete existence as our own. This more cautious approach allows for the exploration of counterfactual scenarios and hypothetical possibilities without committing to a radical redefinition of what it means to exist. In this way, one can engage with the philosophical insights offered by modal realism while maintaining a healthy skepticism towards its more radical implications. Ultimately, the choice to accept or reject particular aspects of Lewis's modal realism is a deeply personal one, shaped by one's own philosophical commitments and intuitions. As Descartes famously declared, "Cogito, ergo sum" – I think, therefore I am. Perhaps, in contemplating Lewis's modal realism, we should similarly say, "Cogito, ergo dubito" – I think, therefore I doubt. And in that doubt lies the potential for new insights and discoveries, as we navigate the complex terrain of alternative possibilities and seek to understand the nature of reality in all its manifold dimensions.