Making Metaphysics Functional

Amie L. Thomasson opens this course by arguing that metaphysics, at least as it's been practiced in analytic philosophy since 1950, has become dysfunctional. The traditional picture holds that metaphysicians discover deep truths about ultimate reality, uncovering what exists, the nature of things, and what grounds what. But Thomasson argues that this picture has led to a proliferation of rival theories with no clear way to settle disputes, skepticism about the field even among philosophers, and an unnecessary rivalry with the natural sciences. Her diagnosis: the trouble stems from what she calls "functional monism": the assumption that all language works the same way, describing features of the world, when in fact different parts of our discourse serve very different purposes in human life.

The alternative Thomasson proposes is to rethink metaphysics as conceptual engineering. This involves two phases: reverse engineering, which asks how our existing language and concepts actually function, and constructive engineering, which asks what we should do with them going forward. She traces the roots of this idea through the history of philosophy and draws on linguistics to show how we can rigorously identify the functions of different kinds of talk without relying on mysterious metaphysical insight.

With this framework in hand, Thomasson turns to a series of classic philosophical problems. She examines number talk and property talk, showing that once we understand the linguistic roles these expressions play, longstanding puzzles about whether numbers or properties "really exist" begin to dissolve. She then takes up moral discourse, arguing that understanding how moral language functions can protect us from the slide into nihilism and skepticism without requiring us to posit strange moral entities. Her treatment of truth follows a similar pattern: rather than searching for what makes our claims true in some deep metaphysical sense, she asks what the concept of truth does for us, arriving at an account that preserves the importance of truth while stripping away the mystery.

In the final lecture, Thomasson turns to the forward-looking side of conceptual engineering. She explores when and why we should revise our concepts, taking up charged examples like race, gender, marriage, and death. These are not idle academic exercises; how we define and deploy these concepts shapes law, policy, and everyday life. Philosophy, on this view, is not a rival to science but something distinct and indispensable: the ongoing, never-finished work of examining and improving the conceptual tools through which we understand ourselves and one another.

This course is accessible to newcomers to philosophy and is meant for anyone curious about what metaphysics is, why it matters, and how it might be done differently.