Varieties of Twentieth Century American Naturalism

Naturalism dominated twentieth century American philosophy.¹ Naturalism is a philosophical worldview that relies upon experience, reason, and especially science for developing an understanding of reality. Naturalism demands that these three modes of understanding together shall control our notion of reality. Varieties of naturalism emerge because the many essential factors of experience, reason, and science can be coherently related in numerous ways. All naturalisms demand that experience, reason, and science be taken most seriously so that no fourth mode of understanding can be permitted to override them. This triadic unity moderates the excesses of phenomenalism and idealism, and filters out spiritualism and supernaturalism for their introduction of radical and mysterious discontinuities into knowledge and reality.

Scientific method and knowledge play a crucial role in all naturalisms. Varieties of naturalism may be distinguished along three dimensions: the degree of ontological confidence given to science; the breadth of explanatory discretion given to science; and the number of scientific fields permitted to describe reality. From the logically possible combinations resulting from these dimensions, seven viable varieties of naturalism are distinguished and contrasted. Each of these varieties of naturalism has had champions in the course of twentieth century American philosophy, such as Dewey, Whitehead, Santayana, Quine, Sellars, Davidson, Churchland, Putnam, and Searle.

The conclusion discusses the three major competitors during the twentieth century for the title of the “genuine” naturalism: Reductive Physicalism, Non-Reductive Physicalism, and Perspectival Pluralism. The struggles among these great naturalisms and the other viable varieties of naturalism have been bequeathed to the twenty-first century, and their outcomes may decide the ultimate fate of naturalism itself.

I

Stage One: Science, Knowledge, and Reality. There are six primary options when considering whether science yields knowledge about reality:

1. 1. Reality cannot be known at all—radical skepticism.

2. 2. Reality only consists of what science cannot know about—only other non-sciences know reality.

3. 3. Science rarely gives reliable knowledge about reality—other non-sciences know reality far better.

4. 4. Science is able to give increasingly reliable knowledge about reality.

5. 5. Science is the only source of knowledge about reality.

6. 6. Reality only consists of what science knows about.

Each of these six options present pathways to many different worldviews. Because naturalism at minimum presupposes that the knowledge about reality provided by science can seriously rival any other alleged source of knowledge, options 1, 2, and 3 are rejected by naturalists. Options 4, 5, and 6 can lead to varieties of naturalism.

(4) Science is able to give increasingly reliable knowledge about reality. There may be other ways besides science for knowing reality, but those ways are not better than science. Science needs assistance from other ways of knowledge to fully understand reality. This option searches for a comprehensive worldview formed by blending together ways of knowledge. Two interesting varieties:

(4)A. Ontological Dualism: there are two (or more) kinds of reality, knowable through two or more ways. For example, perhaps introspection is a non-scientific way of knowing reality because we are consciously aware of mental realities that science can never explain—leading to Mind-Body Dualism.

(4)B. Synoptic Monism: there is only one kind of ultimate reality, but it is knowable through two or more ways. We consciously know of realities (perhaps mental in nature) that science cannot fully explain. Varieties include Dual Aspect Monism and also Panpsychism, which holds that the natural world explored by science is ultimately composed of entities that have a mental/spiritual aspect. Unlike option (4)A, synoptic monism can be used to develop kinds of naturalism.

(5) Science is the only source of knowledge about reality. The only type of knowledge is scientific knowledge. However, some of reality consists of entities that cannot be known by science, simply because science is not designed to provide knowledge about these entities. Two interesting varieties:

(5)A. Perspectival Realism: we are acquainted with the entities unknowable through science because we experience these entities in some other way. For example, much of experience that provides the data for science is not itself also known by science. Specific types include Emergent Naturalism (mental entities emerge...