I. Biological Naturalism as Scientifically Sophisticated Common Sense

John R. Searle

“Biological Naturalism” is a name I have given to an approach to what is traditionally called the mind-body problem. The way I arrived at it is typical of the way I work: try to forget about the philosophical history of a problem and remind yourself of what you know for a fact. Any philosophical theory has to be consistent with the facts. Of course, something we think is a fact may turn out not to be, but we have to start with our best information. Biological Naturalism is a theory of mental states in general but as this book is about consciousness I will present it here as a theory of consciousness.

I. Biological Naturalism as Scientifically Sophisticated Common Sense.

Suppose you did not know anything about the great history of the philosophical mind-body problem, but suppose also that you had a normal adult mental life—you were not a zombie and not suffering aphasia, split brain, blind sight, or any other of the philosophers’ favorite mental maladies. Suppose also that you had a reasonable scientific education. You understood something about the atomic theory of matter, and the evolutionary theory of biology, and you even understood something about animal biology, including a basic knowledge of the elements of neurobiology. I am in short imagining you as you probably are, an educated healthy adult, but I am imagining you without any philosophical history, as you almost certainly are not. Now suppose you asked yourself to describe the nature of consciousness and its relation to the brain. You know the nature of consciousness from your own experience (and not from “introspection. ” That term already has a philosophically loaded history); and its general relations to the brain will have to fit what you know about nature in general as well as what you know about neurobiology. What would you come up with?

Well, here is what I came up with; and if you could just forget about Descartes, dualism, materialism, and other famous disasters I think you would come up with something very similar. First we need a working definition of “consciousness”. Nothing fancy, just enough to identify the target of the investigation; Consciousness, I say, consists in all of one’s states of awareness. Awareness might seem too restricted, so just to be sure to cover all forms of consciousness, I flesh out the definition by adding awareness or sentience or feeling. And then I give an indexical component to the definition, to bring it down to concrete reality. I say: Conscious states are those states of awareness, sentience or feeling that begin in the morning when we wake from a dreamless sleep and continue throughout the day until we fall asleep or otherwise become “unconscious ”.

On this definition, dreams are a form of consciousness, though quite different from normal, awake consciousness.

Having identified the target in general terms I now need to identify its essential features. Here are four of the most important.

1. Conscious states, so defined are qualitative, in the sense that there is a qualitative feel to being in any particular conscious state.

This is the “what-it-feels-like” feature of consciousness. For example, tasting beer is qualitatively different from listening to Beethoven’s Third Symphony. Some philosophers use the word “qualia” to mark these qualitative states, but since consciousness and qualia are coextensive, it is unnecessary to introduce another expression. All qualia are conscious states, all conscious states are qualia. It is important to hammer this point home. There are not two kinds of conscious state, one qualitative, one nonqualitative. All conscious states are qualitative.

2. Such states are also ontologically subjective in the sense that they only exist as experienced by a human or animal subject.

In this sense the tree outside my window has an objective ontology, but my conscious visual experience of the tree has a subjective ontology. The objective-subjectivedistinction is ambiguous and we need to disambiguate it before we go any further. First, there is an epistemic sense of the objective-subjective distinction. The claim that Rembrandt was born in 1606 is a matter of objective fact. The claim that Rembrandt was a better painter than Rubens is a matter of subjective opinion. Objectivity and subjectivity in this epistemic sense are features of claims. But in addition to the epistemic sense there is an ontological sense of the distinction. Most things, such as mountains, molecules and tectonic plates exist apart from any experiencing subject. They have an objective or third personontology. Some things, such as pains and tickles and itches, only exist when experienced by a human or animal subject, and they have a subjective or first person ontology. Consciousness is ontologically subjective in the sense that it only existswhen experienced by a human or animal subject. It is important to emphasize that you can have epistemically objective knowledge of a domain that is ontologically subjective. It is for this reason that an epistemically objective science of ontologically subjective consciousness is possible.

3. Furthermore, a striking fact, at any moment in your conscious life all of your conscious states are experienced by you as part of a single unified conscious field.

Your conscious states at any moment are parts of a single big conscious state. The visual experience of the tree, the tactile experience of the desktop under my hand, and the sight of the moon outside my window are parts of a single total conscious experience. But other entities in the world are not like that. The tree, the desk, and the moon are not in that way parts of a single total big object.

Features 1-3, qualitativeness, subjectivity and unity, are not separate and independent. For a state to be qualitative in this sense implies that it is subjective. For a state to be qualitative and subjective implies that it is part of a unified field of qualitative subjectivity, even if it is the only thing in the field. If you try to imagine your present conscious field broken into seven parts you will find yourself imagining not one conscious field in seven pieces, but rather seven separate conscious fields.

4. Most, but not all, conscious states are intentional, in the philosopher’s sense that they are about, or refer to, objects and states of affairs.

I said we were going to forget about the history of the subject and just state facts we all know. “Intentionality” is a word with a sordid history, so forget about the history if you can. (Forget about, “Intentionality is the mark of the mental” and other famous mistakes.) My states of thirst, hunger, and visual perception are all directed at something and so they fit the label of being intentional in this sense. Undirected feelings of well being or anxiety are not intentional.

So now we have a definition and a description of some of the essential features. What more can you say? Well, if we are going to be careful we want to block some possible misunderstandings. We need to add:

Consciousness so defined does not imply self-consciousness.

You can be conscious of something without a higher order consciousness that you are conscious of it.

Also, you do not need a general second order consciousness to have a first order consciousness.

You can feel a pain, without necessarily reflecting on the fact that you are feeling a pain.

So far we have identified are target, described its essential features and even blocked some misunderstandings. Now we need to say how it fits into the rest of the real world.

1. The reality and irreducibility of consciousness. Conscious states, so defined, are real parts of the real world and cannot be eliminated or reduced to something else.

Often when we get a complete causal explanation of something we can show that it can be eliminated as an illusion – this happened with sunsets and rainbows, for example – or that it can be reduced to some more basic phenomena; it can be shown to be nothing but some micro phenomena – this happened to liquidity and solidity, for example. With consciousness we can neither eliminate it nor reduce it to something else.

We can eliminate something when we show that the epistemic basis for it was an illusion. At dusk it looks like the sun is setting over Mt. Tamalpais and, when we see a rainbow, it looks like there is an arch in the sky, but in both cases the appearance is an illusion generated by more basic real phenomena – the rotation of the earth on its axis relative to the sun and the refraction of light rays by water vapor. But we can’t do this eliminative reduction with consciousness, because the epistemic basis is the reality itself: if it consciously seems to me that I am conscious then I am conscious. We can make lots of mistakes about our own consciousness, but where the very existence of consciousness is in question we can’t make the appearance-reality distinction, because the appearance of the existence of consciousness is the reality of its existence.

We cannot do an ontological reduction of consciousness to more fundamental neurobiological processes, for a reason that is implicit in what I have already said: consciousness has a subjective or a first person ontology, the neurobiological causal basis of consciousness has an objective or third person ontology. You can’t show that a first person ontology is nothing but a third person ontology. I will say more about this point later.

The causal reducibility of consciousness leads to our next point.

2. The neuronal basis of consciousness. All conscious states are caused by lower level brain processes,

We donot know all the details of exactly how consciousness is caused by brain processes, but there is no doubt that it is in fact. The thesis that all of our conscious states, from feeling thirsty to experiencing mystical ecstasies are caused by brain processes is now established by an overwhelming amount of evidence. Indeed the currently most exciting research in the biological sciences is to try to figure out exactly how it works. What are the neuronal correlates of consciousness and how do they function to cause conscious states?

The fact that brain processes cause consciousness does not imply that only brains can be conscious. The brain is a biological machine, and we might build an artificial machine that was conscious; just as the heart is a machine, and we have built artificial hearts. Because we do not know exactly how the brain does it we are not yet in a position to know how to do it artificially.

3. The neuronal realization of consciousness. All conscious states are realized in the brain as higher level or system features.

Everything that has a real existence has it in a single space/time continuum and the real existence of consciousness is in human and animal brains. But conscious experiences do not exist at the level of individual neurons and synapses. Thoughts about your grandmother, for example, are caused by neuron firings and they exist in the brain as a feature of the system at a higher level than that of individual neurons.

4. The causal efficacy of consciousness. Conscious states, as real parts of the real world, function causally.

Typically, for example, when I make a conscious decision to raise my arm and my arm goes up, my decision caused my arm to go up. As with all physical systems, the brain admits of different levels of description, all of which are causally real levels of one and the same causal system. Thus we can describe my arm going up at the level of the conscious intention-in-action to raise my arm, and the corresponding bodily movement, or we can describe it at the level of neuron firings and synapses and the secretion of acetylcholene at the axon endplates of my motor neurons, just as we can describe the operation of the car engine at the level of piston cylinders and spark plugs firing, or we can describe it at the level of the oxidization of hydrocarbon molecules and the action of metal alloys. In both the case of the brain and the case of the car engine, these are not separate causal structures; it is a single causal structure described at different levels. Once you see that the same system can have different levels of description which are not competing or distinct, but rather different levels within a single unified causal system, the fact that the brain has different levels of description is no more mysterious than that any other physical system has different levels of description.

I have now given a definition of consciousness, a brief account of some of its most important structural features, and a general statement of its relations to the brain and other parts of the real world. At one level, this amounts to a proposed solution, or perhaps better a dissolution, of the traditional mind-body problem. The views I have advanced, are, appropriately understood, matters of scientific common sense in that they are, I believe what one would say if one had a modicum of scientific knowledge but was free of the traditional philosophical categories. Notice that in advancing the views I put forward, I made no use of the traditional philosophical vocabulary. None of the famous theories and issues were mentioned, such a dualism, materialism, epiphenomenalism, Cartesianism, or all the rest of it. If you take seriously the so-called “scientific world view” and forget about the history of philosophy, the views I put forward are, I believe, what you would come up with.

To have a name, I have baptized this view, Biological Naturalism. “Biological” because it emphasizes that the right level to account for the very existence of consciousness is the biological level. Consciousness is a biological phenomenon common to humans, and higher animals. We do not know how far down the phylogenetic scale it goes but we know that the processes that produce it are neuronal processes in the brain. “Naturalism” because consciousness is part of the natural world along with other biological phenomena such as photosynthesis, digestion or mitosis, and the explanatory apparatus we need to explain it we need anyway to explain other parts of nature. Sometimes philosophers talk about naturalizing consciousness and intentionality, but by “naturalizing” they usually mean denying the first person or subjective ontology of consciousness. On my view, consciousness does not need naturalizing: It already is part of nature and it is part of nature as the subjective, qualitative biological part.

Just so I do not sound like I am talking about something abstract and ethereal let me nail the whole discussion down to reality with a real life example. Right now I feel a conscious desire to drink a cold beer. This desire is real in the sense that it cannot be shown to be an illusion or reduced to something else. This desire is subjective in the sense that it has first person ontology, the desire is qualitative in the sense that it has a certain qualitative feel to it, and it is definitely intentional in the sense that is directed at or about beer drinking. Furthermore it occurs as part of my total conscious field at the moment. My current feeling of desire is entirely caused by brain processes, it is located in the brain and it will very soon function causally by motivating me to go the refrigerator and pour myself a glass of cold beer.

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