In philosophy, naturalism is the conception that everything that exists – objects and events – can be explained by natural causes or principles. Extending all forms of transcendence, naturalism conceives of philosophical activity as an extension of scientific activity.
Naturalism must not be confused either with materialism or with the Naturphilosophie of German idealism which, at the beginning of the nineteenth century, claimed to give a metaphysical explanation to the evolution of the world. Materialism implies a form of naturalism, but the opposite is not always true. Historically, however, these two conceptions of the world have developed together.
Naturalism today largely falls within the context of the analytic philosophy which, since its “ontological” turn no longer consists solely in the logical analysis of language but, more broadly, in an argumentative discourse aimed at understanding of the world and of ourselves in accordance with the data of the natural sciences.
Origin and history
Naturalism is part of a long history, dating back to antiquity, but it has also become one of the most important contemporary philosophical movements, largely prevalent in English-speaking countries.
In Greek and Roman antiquity, some philosophers like the Stoics and the atomists (especially Democritus and Epicurus) refuse any implication of forces or supernatural entities. For them, the gods can only have an effect in the natural world if they themselves are part of the natural world. The same is true of the human soul whose notion is either rejected or “naturalized”.
The Stoics, in particular, justify the succession of causes and consequences (nexus causarum) by an entirely deterministic conception of the world based on the notion of “destiny”.
Baruch Spinoza is sometimes considered to be the first of modern naturalistic philosophers inasmuch as he is the first to clearly define nature as the sum of all that exists and to explicitly refuse any recourse to external causes in the explanation of the world.
In contemporary philosophy, the proponent of the family of theories for whom metaphysical entities or norms of a given type (logical, mathematical, ethical or cognitive principles) are entirely reducible to the kinds of objects or laws studied in the natural sciences (physics, biology, psychology, etc.), is generally termed “naturalist”. Psychologism, which was vigorously opposed by the pioneers of analytic philosophy and phenomenology (Frege and Husserl, respectively), first constituted the paradigm of philosophical naturalism.
W. V. O. Quine is, to a large extent, responsible for the current preeminence of naturalism among Anglo-Saxon philosophers, because he knew how to precisely define the method and developed a reflection on it. He was undoubtedly the most systematic and uncompromising naturalist of the twentieth century. Naturalism corresponds to the idea that there is no higher tribunal of truth than science itself. There is, therefore, no better method than the scientific method for judging assertions of science, and there is no need for this to resort to a “primary philosophy” such as metaphysics or epistemology. On the other hand, there is no supra-scientific or transcendent point of view for Quine that allows us to know more than what our latest and best science teaches us.
While many philosophers have contributed to naturalism and accepted Quine’s general position, his conception has nonetheless elicited many critical responses from his successors. Much of the analytical philosophy of the second half of the twentieth century was even developed in direct opposition to Quine. The list of naturalist philosophers who have criticized him includes such significant authors as Saul Kripke, Jaakko Hintikka, David K. Lewis, Jerry Fodor and Hilary Putnam. To different degrees, all these philosophers have objected to the implications of Quine’s naturalism, especially against certain radical consequences such as his strict behaviorism in the mental life and his rejection of equivocal notions such as the notion of possibility.
Monism and rejection of transcendence
The idea that the world is one and causally closed (without external cause) is a central claim of philosophical naturalism since its origins: no event in the world can be caused by anything that would be outside the natural world.
According to David M. Armstrong, philosophical naturalism is a form of philosophical monism that has two components, one ontological (concerning what exists) and the other epistemological (concerning knowledge). From the ontological point of view, naturalism maintains that there is nothing outside of nature, while on the epistemological level it asserts that the natural sciences are the only pathways to authentic knowledge. Presented in its most succinct form, naturalism is thus the combination of two essential principles:
- the natural world is all that is, and its existence requires no supernatural or supranatural cause (ontological principle)
- we do not possess any unnatural source of knowledge (epistemological principle).
The ontological ambition of naturalism is to develop a coherent and complete vision of nature on the basis of scientific theories. David M. Armstrong and David K. Lewis are among the leading philosophers to have contributed. This project is termed “metaphysical naturalism” by some authors, notably by Richard Carrier, Martin Mahner and Michael Esfeld, in the sense that it is based on the idea that everything that “exists” belongs to nature, understood as a spatio-temporal world governed by laws.
The first ontological thesis of naturalism is negative: naturalism rejects the notion of transcendence. The universe, and all the entities that compose it, covers all that exists and there is therefore no supernatural or supranatural cause capable of explaining it. Naturalism, therefore, conceives of man as a production of nature which has no other justification than the natural causes which brought him to existence (we thus speak of “incidental” production: man is an integral element of nature and is therefore not a product “derived” from nature).
Since Charles Darwin, naturalists explain all living production by evolution without supernatural intervention and without teleology or intelligent design: all organized forms of life, even the highest, are ultimately derived from non-living matter by a blind mechanical process of transformation and organization of this matter. According to the philosopher Daniel Dennett, it is this ability of Darwinian theory to explain life without recourse to entities or transcendent principles that confers on it its strength and validity. Darwinism is a response to the question of origin, which is for Dennett and the naturalistic philosophers of today an authentic model of naturalistic explanation.
Strict (or “Quinean”) naturalists oppose philosophers who claim that we can use certain intuitions of common sense as a starting point for philosophical reflection. In general, their criticisms of common sense and philosophical intuitions unfold on two fronts:
- they question the validity of the point of view offered by introspection;
- they reject the possibility of a transcendent view of the world (which Hilary Putnam ironically calls the “eye of God”).
The first point inscribes naturalism in an anti-Cartesian tradition that goes back to Spinoza and rejects the idea that there would be a privileged point of view that would be that of the “me” on its own states. The second point makes naturalism a philosophical anti-dogmatism. In its most radical form, naturalism is opposed to the idea that philosophers can discover a priori truths and he argues that a philosophical statement is considered true only in a temporary way. None of our knowledge is held sacred or intangible. Naturalism is distinguished in this sense from philosophical materialism which is a definitive ontological position.
For naturalists, our best view of reality is that given to us by our best and last science. For them, philosophy is not a more fundamental activity than the sciences of nature. Natural sciences and philosophy are thus seen as two ongoing activities. For Quine in particular, there is no real separation between these two ways of understanding the world, so that philosophical reflection does not involve anything particularly special or unique, which forces the philosopher to a form of intellectual modesty:
“I do philosophy – recognize Quine – only from the point of view of our conceptual schema and our scientific era, both provincial, it’s true, but I do not know a better way.”
Apart from transcendence both in the epistemological field and in the field of ontology, naturalists prefer to see philosophy and science as collective activities subject to the same elementary norms. Because these activities are related, the naturalist argues that scientific research and discovery can improve or revise our philosophical heritage. He therefore believes in the possibility of some progress in philosophy.