Pragmatism and Ontological Pluralism: Peirce, Cartwright, and Dupré

—all this being so, there must be exactly as many species of being as of unity.

—Aristotle, Metaphysics IV.2 1003b33–34

I. Introduction

Commonsense philosophy is committed to making sense of everyday experience rather than dismissing or rejecting it entirely. Commonsense philosophers are critical of over-idealized and abstract philosophies, which favor pure theory at the cost of failing to make sense of everyday life. In this respect, commonsense philosophy is a friend to pragmatism. Charles S. Peirce surely sees it this way. He follows the Scottish commonsense school, which rejects skeptical critiques of commonsense beliefs. We accept our most basic commonsense beliefs because inquiry must start somewhere and because we cannot pretend to doubt these instinctual beliefs.¹ But Peirce also holds an important role for criticism and theoretical inquiry in his commonsense philosophy. Deliberative inquiry, such as scientific inquiry, can and should correct our commonsense beliefs. For example, Western culture updates commonsense medical beliefs with advances in microbiology and updates commonsense beliefs about the moon’s orbit with the theory of gravitational pull. Yet it still seems far-fetched that our commonsense beliefs could incorporate conclusions from science regarding neutrinos and electromagnetic fields. We do not appeal to them in our everyday explanations of things, and it is hard to imagine that we will. We seem to treat our everyday experiences as practically distinct from the idealized world of particle physics.

In this paper we examine the relationship between commonsense beliefs (e.g., the order of nature, or our basic ideas of space) and scientific theories (e.g., evolution or electromagnetism), according to Peirce. On the one hand, Peirce holds that science sometimes employs concepts of common sense, while, on the other hand, he also holds that science sometimes questions and criticizes commonsense beliefs and moves beyond them in important ways. We argue that, for Peirce, we use commonsense thinking in idealized contexts of scientific inquiry, but these contexts are often so practically distinct from one another that we cannot reconcile them. We further argue that this need for two different kinds of accounts is indicative not just of an epistemic difference but also an ontological difference, and that reality is made up of different kinds of stuff. We employ arguments from the Stanford School of the Philosophy of Science philosophers, namely, Nancy Cartwright and John Dupré, who argue that lack of unity among the sciences, in practice, indicates ontological pluralism. We see their view as pragmatistic because they hold that practice informs our theory of reality. Now, it is true that in a letter to William James, Peirce explicitly rejects pluralism (CP 8.262).² And yet some argue that Peirce does, in fact, hold this very view of ontological pluralism. In general, we agree with this view, even while acknowledging that Peirce may not have been consistent in holding it. But we argue specifically that ontological pluralism should be his view given his commitment to apply pragmatism to all ideas including the idea of reality itself and because common sense and science offer two different accounts of reality that are supported by experience. We should not accept a view of reality that is so different from our experience of reality. Of course, sometimes there is unity, or rather, there are unities. But we should not pretend unity exists where there is no evidence for it, nor should we ignore evidence against unity.

II. Peirce on Ontological Pluralism

Whether there are other reasons to believe Peirce holds or should hold ontological pluralism is beyond the scope of the present argument, but a brief discussion of the issue will be helpful going forward. First, it might look like Peirce is an ontological pluralist, holding that there are different kinds of irreducible realities, because Peirce rejects absolute uniformity in nature. For example, in “The Order of Nature,” against the view that the universe is a “pure throw of the dice,” without laws or even similarities among things, Peirce argues that the world is not an “exact poem” (EP 1:172). While there may be a contradiction in trying to imagine a world without uniformities...