Naturalism is the prevailing philosophical paradigm in the philosophy of mind and yet specifying what naturalism means is not straightforward. In his book Philosophy in the Age of Science, Hilary Putnam compares, perhaps somewhat facetiously, philosophers’ declarations of adherence to naturalism to the routine declarations of conformity to Stalinism that writer’s in the post-war Soviet Union would have to include in their work, while at the same time leaving the nature of Stalinism undefined and thereafter paying it little heed.

Markus Gabriel cites this passage in his recent essay Neo-Existentialism, in which he puts forward a critique of naturalism and proposes an alternative which he calls neo-existentialism. Gabriel’s neo-existentialism draws on the tradition of philosophical thinking that can be found in the works of Kant, Hegel, Kierkegaard, Nietzsche, Heidegger and Sartre. The organising idea in this tradition is the concept of Geist, a term that Gabriel largely leaves untranslated as it doesn’t really map to either mind or spirit as these terms are typically used in English. In contrast to natural entities which are mind-independent and function independently of any conceptual structure, geistig entities are mind-dependent and their behaviour depends in some way on a conceptual structure.

He argues that philosophical naturalism has at its base two claims, namely:

  1. A metaphysical claim – everything which really exists is woven into the causal web studied by the natural sciences.
  2. An epistemological claim – everything which really exists can best be explained by recourse to the methods of theory construction used in the natural sciences.

When applied to human beings, this leads in the direction of what Gabriel calls neuro-centrism. This neuro-centrism has two main pillars: firstly, the view that what seem to us to be minded events are in reality events in the neural system and, secondly, and as a corollary, that human behaviour can be explained by the discoveries of neuroscience working within the framework of evolutionary biology.

Philosophical naturalism tends to assume that that the better we know the natural entity the brain, the safer it will be to identify mind and brain. Gabriel’s neo-existentialism, on the other hand, is based on a conditional model of the relationship between mind and body for which the relationship between bicycles and cycles can serve as a toy model. Bicycles do not cause cycling and cycling cannot be reduced to bicycles. The existence of bicycles is a necessary but not sufficient condition for the activity of cycling. The relationship between mind and body is, similarly, an arrangement of necessary and sufficient conditions. Having a suitable brain is a necessary condition for mindedness, but the physical processes of the body can never be sufficient to determine the activities of the mind.

Why cannot the brain be sufficient for the mind. In the theory of neo-existentialism there is no single phenomenon or reality corresponding to the term mind. Gabriel’s argument is that the domain of the mindis much more extensive than the domain of nature. The mind brings with it the capacity to build institutions in the light of our socially mediated map of how actions and their explanations fit into a larger context, a frame which it larger than the natural order. As human beings we constantly transcend our given situation and integrate it into a larger cartography of how things hang together. Naturalism fails because the finite natural order, while necessary, is not a sufficient basis for the unbounded minded order that he calls Geist.

At bottom, the concept of the mind is designed to distinguish the human from the non-human. Our self-portrait as minded is in place in order to make sense of the fact that we do not belong in the domain of what merely exists. At its core, mindedness is the activity of making sense of human beings as distinct from every other kind of being; distinct from animals, from plants and from inorganic entities.

We live our lives assuming that other people live their lives under different assumptions. In this regard, human beings are different from plants. We don’t explain the behaviour of a plant on the assumption that the outward activity that we are explaining is the expression of an inner activity that we cannot observe directly. However, when we seek to explain human behaviour, we do posit such an inner activity. We work on the premise that we are looking in the mirror. We cannot observe this inner activity in others directly, but we assume that there is symmetry between ourselves and others, and the interiority that we are aware of in ourselves has an analogue in everyone else.


I am sympathetic to what Gabriel is trying to do but I think there are a number of problems. One set of problems is concerned with the critique of philosophical naturalism, a second set is concerned with the proposition of an alternative.

The first problem is defining the target of the critique. Although he cites Putnam’s remark that the function of naturalism as to make a reassuring statement that what follows will not contain any magical thinking, I don’t think Gabriel does this, tending to conflate naturalism with scientific materialism. I would argue that scientific materialism is a version of naturalism, rather than the same thing.

A simplified and non-exhaustive typology of naturalism might look something like this:

  1. Reductive Naturalism
    1. Reductive materialism
    1. Reductive idealism
  2. Non-reductive Naturalism
  3. Reductionist Naturalism
    1. Evolutionary Psychology
    1. Neuro-centrism
  4. Reasonable Naturalism  

The hypothesis underlying reductive naturalism is the causal closure of physics. It can come in both materialist and idealist versions. Reductive materialism is based on the proposition that the micro-scale is an entirely natural system. The primary task for someone who adheres to this view is therefore to show how what is meaningless at the micro-scale can manifest itself as the meaningful world we inhabit at the macro-scale. Daniel Dennett is perhaps the leading advocate of this view.

Although reductionism often goes to together with reductivism the ideas are distinct. The difference is firstly a question of scale. A reductivist believes that the course of events is determined completely at the micro-scale of physics. A reductionist, on the other hand, seeks to explain macro-scale cultural events in terms of macro-scale natural events. Reductivism is more a metaphysical principle than a practical project. Explanation is offered as if the system were culturally determined, by adopting what Dennett calls stances. Nobody would actually try to explain an economic system, for example, in terms of particle physics. Reductionism is a possible explanatory strategy in the way that evolutionary psychology, for example, seeks to explain cultural events as the outcome of evolutionary biology.

Scientific materialism is another label for reductive materialist ontology coupled with reductionist strategies of explanation. What I am calling reductive idealism takes a different approach. Reductive idealism reasons that if there is a meaningful macro-scale and the course of events is determined at the micro-scale then it must follow that at least some events at the micro-scale are also meaningful in some way. Panpsychism, the idea that all entities are minded, is one version of this idea. Thomas Nagel’s natural teleology is another. The underlying sentiment has been expressed by Freeman Dyson in his view that mind and intelligence are woven into the fabric of our universe in a way that altogether surpasses our comprehension.

Unlike reductive materialism, therefore, reductive idealism will tend to be anti-reductionist. Thomas Nagel’s argument in Mind and Cosmos is targeted both at reductive materialism and what he calls Darwinism, the reductionist approach to cultural explanation. This is because in the idealist model the necessary mechanisms for meaning, value and purpose are embedded in the micro-scale. From this perspective, while natural macro-scale events are the manifestation of natural micro-scale events, meaningful macro-scale events are the manifestation of meaningful micro-scale events and therefore the reductionist approach to explanation is unnecessary.

Non-reductive versions of naturalism, on the other hand, are a set of attempts to avoid the embrace of the causal closure of physics but stay within the bounds of naturalism. Typically, non-reductive naturalism argues that in some way minded entities supervene on natural entities. One thing supervenes on another if there cannot be a difference in the supervening entity without a difference also in the entity on which it supervenes. However, this relationship in itself remains agnostic about how the entities are related and how they interact.

There is a proliferation of non-reductive theories. Many of these, instead of a thinking in metaphysical or epistemological terms, approach the topic through semantics, that is, the relationship between meaning and the world. Examples are the truth-conditional semantics proposed by Joseph Levine and the two-dimensional semantics put forward by David Chalmers. In two-dimensional semantics, there is a primary (actual) intention – e.g. water is a liquid at room temperature, and a secondary (necessary) intention – the term water refers to a sample H₂0 molecules. When words are applied to natural entities, these meaning can come apart. However, when applied to minded entities, the terms cannot come apart in this way. The argument is that if there is a semantic gap it is evidence that there is a metaphysical gap. The intuition underlying these approaches is that the discontinuity between the way we apply words to the natural order and the way we apply words to the cultural order is a real discontinuity and this is an indicator that the mind is not reducible to the brain.

Although Gabriel agrees with Levine and Chalmers that there is something special about our minded vocabulary, he disagrees with how they locate the semantic gap. Gabriel reverts to the idea that natural entities are natural kinds, a semantic model based on the externalist theories of reference developed by Putnam and Saul Kripke. The idea here is that the meaning of terms is external to the culture that uses them. Pre-scientific civilisations did not know that water has the molecular structure represented symbolically as H2O but, nonetheless, a sample of water was and always will be defined as a sample of stuff with that molecular structure.

When an ancient Greek referred to a sample of something as thalassa, what they were referring to had to be a sample of H2O, even though the molecular structure of water was unknown at that time. Kripke has been responsible for re-introducing an intuitive essentialism into naturalism and this approach to reference appears to require some form of metaphysical essentialism to make it plausible.

Lastly, I have included the concept of the reasonable naturalist, a figure invoked by Jocelyn Maclure in his introduction to Gabriel’s essay. Reasonable naturalism is non-reductivist and non-reductionist. Reasonable naturalism can be thought of as a form of abductive thinking which works backwards from the successes of natural science and the technology that it supports to the view that it is likely therefore to be our best way of explaining the world. Reasonable naturalism will therefore tend to support non-reductive rather than reductive and reductionist strategies. 

This kind of analysis suggests that different kinds of argument must deployed. It’s not possible to refute naturalism in any simple way, because its adherents have very different concerns and have different ontologies and epistemologies. Against reasonable naturalism I would propose reasonable pluralism. Wouldn’t a reasonable observer, surveying everything we currently know and how we know it, the diversity of things and the incompleteness of our understanding, come to a provisional judgement in favour of a reasonable pluralism rather than a reasonable naturalism.

Against the more intrepid arguments of reductivism, a different strategy is required. Reductivism depends on the casual closure of physics. I would argue firstly that this principle is not supported by modern scientific theories or modern scientific method and, secondly, that it makes no significant difference to the explanation of macro-scale phenomena. While natural science has been extremely successful in the understanding of physical chemical and biological systems, it has had very little success in understanding the cultural mind and our cultural acquisition. The causal closure of physics is metaphysical position based on a misunderstanding of modern science and is an unnecessary and arbitrary assumption which delivers no compensating benefits.


If it is difficult to put forward a critique of one nebulous conceptual structure such as naturalism there is an analogous difficulty making a case from the perspective of a similarly nebulous framework such as idealism. Is Gabriel eliding, as Andrea Kern suggests in a one of the critiques included in this volume, two different things; on the one hand, human experience as a means of explaining how it comes about that a fact is determined by its concept and, on the other hand, human experience as a form of life that is conceived as what it is in virtue of being known by those that manifest it.  

In a critique of Gabriel’s view, Andrea Kern suggest that there is an alternative perspective that she derives from Aristotle and Hegel. What this means is that the sense of being a living being is not the same for both a rose and rabbit and a human. What it means to be a living being is determined differently depending on the 3 different forms. Therefore, life is an abstract unity of capacities that can only be applied to any given living being with a specification of the principle in virtue of which those capacities belong to a single being.

Animal life is not vegetative life with additional functionality and human life is not animal life with additional functionality. Plants cannot be considered individuals. Animals instantiate their life form through perception and therefore as individuals. It has particularity. Human life differs from animal life in that it is rational. Rational beings instantiate their being through intellect. The power of intellect, unlike the power of perception, can instantiate itself as its own concept. Human beings are the particular manifestation of something general.

There are three parts to the analysis: what is the significance of existentialism; how does existentialism fit together with the human sciences and where do we place conceptual structures in the model.

First of all, what do we mean by existentialism? As it was first developed by Heidegger and Karl Jaspers, existentialism was a different way of thinking from the abstract formalism of then prevailing Kantian approaches to philosophy. Instead, it emphasised the particularity of things, the theorists’ engagement with rather than detachment from the world, and the importance of looking beyond the purely cognitive to the practical and the experiential. As a consequence, existentialism was committed to the interior point of view of a particular participant in the world and existential seems to be a reasonable label for ways of thinking from this perspective.

In contrast, the epistemology of naturalism, because it takes its lead from scientific method, is always seeking to be the view from outside, the view of the detached observer, not the participant. Archimedes said ‘find me a place to stand and I will move the earth’ and naturalism hopes that it can find an equivalent Archimedean place to stand from which a detached and objective perspective is available.

Existentialism was not developed as a critique of naturalism. In existentialist thinking, facticity, the property of being a given, comes from other people, not ourselves as biological and physical systems. The ambiguity of the human predicament described by Simone de Beauvoir in her essay Ethics of Ambiguity, in which she articulated the ethical implications of Sartre’s Being and Nothingness, is that we are at the same time a subject to ourselves and an object to others. Subjective freedom has to be constantly maintained against the imposition of facticity by other people. Ethical responsibility is evaded through internalising the external point of view instead of safeguarding, exercising and owning the freedom that comes with the internal point of view.

That being said, the existentialist approach has much the same force against naturalism, which posits biological and physical systems as determinative. This is the significance I believe of the very narrow interpretation of rationality in the naturalist world-view, its tendency to limit rationality to instrumental, algorithmic and utilitarian thinking, and its discomfort with ambiguity, incommensurability and heuristics. If a participant can be assigned the same rationality as an observer, it might be possible to bridge the gap between the external and the internal points of view.

Any worthwhile world-view will contain the existentialist perspective. However, this cannot be the whole of any metaphysics or epistemology, which intuitively ought to integrate the internal and the external points of view. The external point of view is not just the point of view of the natural sciences, it is also the point of view of the disciplines concerned with human societies and cultures. The difference is not that they have found a different place to stand, it is that explanations in these disciplines will be structured differently form disciplines concerned with natural systems. 

A classification of disciplines by target domain might look like this. In the first group we have disciplines concerned with natural systems:

  1. Disciplines concerned with nature: physics, chemistry, biology.

In the second group, we have disciplines concerned with conceptual structures. If we go back to the question of point of view, both the natural order and the conceptual order are seen from the outside. We make discoveries in physics and we make discoveries in mathematics and the discoveries we make in physics and mathematics are interconnected – research in physics drives discovery in mathematics, and discovery in mathematics removes constraints on research in physics:

  • Disciplines concerned with concepts: ontology, epistemology, mathematics, reasoning.

In the third group we have all the disciplines concerned with human society and culture.  remembering that all these disciplines, including the natural sciences and the conceptual disciplines are themselves cultural artefacts and therefore also in this target domain:

  • Disciplines concerned with institutions: sociology, economics, political science
  • Disciplines concerned with individuals: psychology, theory of action
  • Disciplines concerned with cultural artefacts: criticism
  • Disciplines concerned with technology: engineering, computer science
  • Disciplines concerned with the past: history, archaeology
  • Disciplines concerned with disciplines: philosophy.

What distinguishes the third group is that they are structured according to the category that Wilhelm Dilthey called ‘inner and outer’. This means that the entities and events in the target domains are understood as the outward expression of an inner state or activity.

There are a number of dimensions to this idea. Firstly, because we are both the observers of and participants, the target domains are themselves informed by the disciplines which seek to understand them. There is a reflectiveness of discipline and target that is not present with natural systems or conceptual structures. Secondly, the relationship between inner action and outward expression is many to many. By that I mean that the interior activity may be realised in multiple outward forms and an outward form may be the expression of many interior actions. Effectively there is two-way multiple realisation. Thirdly, the inner and outer distinction means that the inner motivation may have no connection to any objective reality. The view from outside must try to interpret the outward appearance for clues to the inner movement which is itself very particular and may not know itself very well. This is the intuition behind the point that mistaken beliefs about who we are functional in a way that mistaken beliefs about natural and conceptual structures are not.

The human sciences therefore are not so much the participants view but they are the view of an observer based on the intuition that what they are observing and seeking to understand is the outward manifestation of the inner thoughts and motivations of a participant, who is existentially engaged in the world. This is in my view the significance of the existential; human experience as a form of life that is conceived as what it is in virtue of being known by those that manifest it.

I think the problem with existentialism as it was originally developed was not just that it didn’t engage with the natural sciences but also that it didn’t engage with the intellectual disciplines in the second group. Conceptual structures, such as the circle are neither natural entities nor social and cultural entities. The circle as a concept is not the outward manifestation of existential experience any more than it is a natural entity. This poses a real problem for materialist versions of naturalism. If the circle is not a natural entity, then naturalism is false. However, if you want to make the circle a natural entity, then materialism is false.

This analysis suggests an ambiguity in Gabriel’s thesis. If the domain of Geist is the domain in which a thing is determined by its concept, then it would appear to deny the existentialist point of view, the point of view of the self-aware being that can foresee future paths and is aware of its own freedom to choose which path to take. It looks a lot more like the idealism that existentialism was developed to challenge, in which agency lies elsewhere, in the idea, and human lives are vehicles through which ideas work out their own contradictions.