Reproductive causation: Revolutionary evolution. There is another reproductive global regularity, because there is a further way in which reproductive cycles can work together with the space containing them to generate another global regularity. It can occur only when reproductive cycles have already been gradually changing for some time in the direction of natural perfection, but it takes evolution beyond that the limit of optimum. The ontological cause comes from a more radical variation in the organisms that have already evolved, namely, higher levels of part-whole complexity in the structures of the organisms going through reproductive cycles. Since such a random variation begins a new stage of gradual evolution, which can in turn make possible yet another such revolutionary change, it generates is a series of stages of gradual evolution, and thus, this global regularity is “revolutionary evolution.”

It is evident that something more is needed to explain evolution on earth. Though the radiation of increasingly powerful organisms into all possible ecological niches can explain some of the variety among organisms, the basic reproductive global regularity implies that evolution is just one long, incremental change. Though gradualism is what Darwin expected, Darwinists now believe that the organisms found on earth are far too various, if not also too complex, to be explained by a gradual change in the direction of ever greater fitness.

Indeed, there is good evidence against gradual evolution. The fossil record reveals that, time and again, after a long period of little change, new species show up quickly, usually many species at about the same time, only to be followed by another long period of very little change. Called “punctuated equilibrium,” this phenomenon cannot always be explained as a radiation in which organisms of some kind acquire the power to tap a new source of usable energy in the environment. Something besides the addition of one new trait after another is helping determine the overall course of evolution.

Reproductive causation offers, however, a simple and plausible explanation of these phenomena. The further way that space can be combined with reproductive cycles to constitute a global regularity entails stages of gradual evolution. Such stages can explain not only why evolutionary equilibria are punctuated by the appearance of many new species all at once, but also why organisms are so much more varied than would be expected of gradual evolution. Furthermore, the sequence of stages makes evolution change in the direction of a natural perfection that is far grander sense than merely maximizing the holistic power of both organisms and ecology. Let us consider, first, the ontological cause of revolutionary evolution, and then the ontological effect itself.

Ontological cause: levels of part-whole complexity. Though the basic ontological cause is reproductive cycles, they can help generate another reproductive global regularity, because reproductive cycles can combine with space to cause ontologically a new stage of gradual evolution.

What goes through cycles of reproduction are the many structural causes bundled together as the complex material structures that I have been calling “organisms.” That part-whole complexity about each organism is what makes it possible for a gradual evolution to go on for a long period, because that is the source of the wide range of random variations that can be tried out and that can accumulate as the many new traits that make organisms increasingly complex, diverse, and powerful. But that same aspect of the nature of organisms suggests another possibility. Once organisms have approached natural perfection for organisms of their kind, it may be possible for those organisms to serve as various structural causes that are bundled together in a new organism, so that they all go through reproductive cycles as a whole. That is what I will call a “higher level of part-whole complexity” in organisms.

Organisms are complex mechanisms that can fairly be said to behave in various ways, because they are bundles of structural causes whose effects work together to control all possible conditions that affect their reproduction. Such parts are responsible for the non-reproductive structural effects that are called “traits,” but their functions, or the relevant conditions they control, may lie either in the organism (determining its physical properties and how they change) or in the world in which the organism exists (such as acquiring energy from the world and sending offspring into it).

The simplest way that a higher level of part-whole complexity is possible is for such organisms to be bundled together as a complex material structure that goes through reproductive cycles as a whole. Each simpler organism that is included would then be a structural cause with effects that are (or become) functional traits of the higher level organism.

(In this case, it is a higher level of part-whole complexity of primary structures. A "primary structure" is a material structure that can generate an entire reproductive cycle, including both reproductive and non-reproductive work, and since the lower level organism is a primary structure, a higher level of part-whole complexity based on such organisms is a higher level of part-whole complexity in primary structures. I use this simple case to introduce the cause of evolutionary stages, though as we shall see, there are other ways in which higher levels of part-whole complexity can cause additional stages of evolution.)

But in order to go through reproductive cycles as a higher level organism, the structural causes combined in its material structure must work together in the cycle to control conditions that affect its reproduction, and what is more, all the parts must be reproduced in order for the higher level organism to be reproduce. Thus, it is also necessary to coordinate their behavior.

A behavior guidance system is, therefore, required for organisms to be combined as parts of a higher-level organism (that is, an organism with a higher level of part-whole complexity in primary structures). Some such system must be part of the random variation that gives rise to the higher level organism.

I will call it a “biological behavior guidance system.” (This is to distinguish it from another kind of behavior guidance system that will also turn up as part of this global regularity, namely, the animal behavior guidance system, whose function is to guide the behavior of whole organisms in acting on other objects in space.) The function of the biological behavior guidance system is to coordinate the behavior of the lower level organisms (or primary structures) of which it is composed so that it can go through reproductive cycles as a whole. And its physical nature depends on the nature of the organisms (or primary structures) whose behavior is being coordinated.

By coordinating the lower level organisms (or primary structures), the biological behavior guidance system will have structural effects that can control conditions that affect reproduction. But in order to go through reproductive cycles, it must also be able to reproduce the higher level organism as a whole. But this is possible, because its parts are organisms that evolved during the previous stage and (as primary structures), they are already able to reproduce themselves. The reproduction of the higher level organism is simply a matter of coordinating its parts to reproduce as part of the same process. But the capacity to control the reproduction of its parts can also be used by the higher level organism to do non-reproductive work.)

In general, it is already possible to see how a higher level of part-whole complexity would cause a new stage of evolution. Assuming that it is possible for reproductive cycles with such higher level organisms to be tried out as a random variation on organisms that have already evolved, they would have the power of a whole army of the structures of lower level organisms to control conditions that affect its reproduction as a whole. This quantum leap in power would enable them to begin a new stage of evolution.

Since they would come to exist at first from a radical random variation, the higher level organisms would start off simple, uniform and weak. But assuming that they go through reproductive cycles, reproductive causation would shape them to control conditions affecting reproduction that were simply beyond the reach of lower level organisms acting separately. That is, as random variations in the kinds, numbers, and arrangement of the lower level organisms (including how their behavior is coordinated) were tried out, the scarcity due to their own population growth would impose a natural selection on them, and the higher level organism would become more complex, diverse and powerful. There would be enough new powers to be acquired for an entire stage of gradual evolution, because the potentially functional traits of a higher level organism are caused by the kinds, numbers and arrangements of its lower level parts. Thus, organisms would change gradually in the direction of natural perfection for organisms of their kind.

As they approach natural perfection for organisms of their kind, however, another such radical random variation may be possible. Its yet higher level of part-whole complexity would begin another stage of gradual evolution. Thus, as one stage followed another, evolution would be an overall change in the direction of what might be called the “natural perfection of life,” in which increased power comes from higher levels of part-whole complexity. 

The spatial derivation of the ontological cause. Higher levels of part-whole complexity in the structures of the organisms going through reproductive cycles are, therefore, the ontological cause of the revolutionary episodes in evolution that being new stages of evolution. Though, as we shall see, such stages of evolution follow one another in such a way that evolution is change in the direction of a grander form of natural perfection, higher levels of part-whole complexity are just a complication of the ontological cause that is already at work in causing gradual change in the direction of natural perfection, the basic reproductive global regularity. Evolutionary change is still just how the wholeness of space makes reproductive cycles add up as time passes. But in causing revolutionary change, space works together with reproductive cycles in a further way, because the structure of space within the region is what makes it possible for the structures of organisms from one evolutionary stage to be bundled together as the various structural causes making up a higher level organism.

The relevant part-whole relation is a kind of spatial relation, and it is because the structures of the the lower level organisms coincide with space that it is possible for them to be combined as the several parts of a higher level organism. This role of space as an ontological cause resembles the role it played in causing structural global regularities, for the structure of space is what made it possible for simpler material objects to be combined as composite objects with geometrical structures and for such material structures to move around in space. And the new (derivative) ontological cause also comes from a new kind of unity, the way in which the structures of lower level organisms are combined as parts of a single higher level structure (just as material structures came from a new kind of unity of material substances that gave them an unchanging geometrical structure as a whole).

Though the part-whole relation in space is also what makes higher level organisms possible, organisms are not just material objects. They must reproduce as well as do various kinds of non-reproductive work in order to go through reproductive cycles. Thus, combining simpler organisms as parts of a higher level organism cannot usually be accomplished by simply attaching them to one another. They need a biological behavior guidance system to coordinate the behavior of their parts.

What makes reproductive cycles a different kind of ontological cause from the complex material structures that go through them is their temporal structure. That is, the new kind of unity behind the ontological cause of reproductive global regularities is the temporal unity of the cycle of reproduction. The way that time is part of the nature of the ontological cause is what makes reproductive global regularities so dramatically different from structural global regularities.

It is, however, space that makes revolutionary evolution so different from gradual evolution. Space together with the structures of lower level organisms constitute the higher level organism, and since space has a structure that allows higher level organisms to go through reproductive cycles, the wholeness of space plays its familiar role, making reproductive cycles add up over time so that the scarcity caused by their multiplication imposes natural selection them and organisms evolve gradually toward natural perfection for organisms of their kind (and help make the ecology naturally perfect in the process).

Since wholes in part-whole relations can be parts of more inclusive wholes, there can be a series of part-whole relations in the structures of material objects. Keeping track of them is what will enable us to trace the stages of gradual evolution that occur in its overall course. Since the notion of “a series of levels of part-whole complexity” is so central to this argument, it is worth the risk of belaboring the point to be clear about what is meant by it.

To illustrate what I mean, consider a box containing many similar cartons each filled with objects of some kind. Both the box and the cartons are wholes made up of parts, but the parts in the box are themselves wholes, namely, cartons, each containing many parts of some kind. It is even clearer how levels of part-whole complexity can form a series, each nested inside the next, when there are more than two levels of part-whole relations. Each of the cartons contained in the box may contain objects that are themselves containers of many similar objects (such as packs of cigarettes).  Or going in the direction of the larger, the boxes of cartons of packs of cigarettes may be loaded together in a semi-truck’s shipping container which, in turn, is contained within a ship’s hull. There is, in principle, no limit to the number of levels of part-whole relations in a series. (In the decimal representations of numbers, for example, each decimal place represents a whole that is made up of ten “parts” in the decimal place to its right, and there is no limit to the number of decimal places in numbers.)

However, the “wholes” that are relevant to reproducing organisms are not just spatial structures made up of spatial parts, but rather spatiotemporal wholes made up of parts generating structural effects, that is, cycles of structural effects. Thus, a better, though still rough, model for a series of levels of part-whole complexity would be the levels of government into which individuals are organized in the United States: local, state and federal. Taking individuals to be the parts in which the simplest structural effects, local government can be seen as wholes that are then parts of state governments, which are wholes that are, in turn, parts of the federal government. There are three levels at which structural effects are bundled together as wholes that are, in turn, bundled together as (complex) structural effects on a higher level of government.

Kinds of levels of part-whole complexity. When a series of levels of part-whole complexity is found in a single organism, there is a determinate order to the material structures involved. And since reproductive causation works from simpler to more complex organisms, the stages of evolution by which the levels of organization accumulate have a determinate temporal order. But the actual series of levels of part-whole complexity that determines the overall course of evolution are of two or three different kinds, and each kind of part-whole complexity involves a different series of levels.

The basic and most obvious series is the series of “levels of biological organization.” They are the kind of part-whole complexity that has been mentioned thus far in describing the ontological cause of revolutionary evolution, in which lower level organisms are bundled together as parts of a higher level organism to go through reproductive cycles as a whole. (Since the material structures of independent organisms are primary structures, which can generate all the structural effects required to complete an entire reproductive cycle, including both reproductive and non-reproductive work, these are levels of part-whole complexity in primary structures.)

Multicellular organisms are the best example of them. Indeed, they are named after the level of part-whole complexity that is obvious in them (being composed of many cells). But it is only one in a series of levels of biological organization.

It should not be surprising that there is at least one more level of part-whole complexity in primary structures in the direction of the small from multicellular organisms, because each of the cells is itself a whole composed of parts that are also primary structures. The behavior of each cell is known to be determined somehow by many genes, and genes do both reproductive and non-reproductive work There is however, as we shall see, an additional level of part-whole complexity between cells and genes (and genes themselves have the part-whole structure required to be complex material structures of the kind required for reproductive causation).

Moreover, there is a level of biological organization above multicellular organisms, for example in insect colonies and, in a unique way as we shall see, in human society, yielding five distinct levels of part-whole complexity in primary structures altogether. 

Within the structure of multicellular animals, however, there is another series of levels of part-whole complexity. It occurs in the nervous system. “Levels of neurological organization,” as I will call them, are capable of causing stages of evolution, because the nervous system is the system for guiding the behavior of multicellular animals, that is, its “animal behavior guidance system.”

The nervous system is composed mainly of neurons, and since neurons are cells, they can also be organized at a series of level of neurological organization. Not only individual neurons, but whole systems of neurons can be multiplied in number and fit together as parts of a super-system of neurons at the next level. But they are not levels of part-whole complexity in primary structures, because systems of neurons are not able to reproduce on their own. They are levels of part-whole complexity in a structure set up by the animal's primary structure.

Since each higher level of neurological organization can open up an entire range of powers that were previously out of reach, the evolution of a higher level can begin a whole new stage of evolution. Then, as it approaches natural perfection for organisms with its level of neurological organization, yet another level can be tried out, and thus, the series of neurological levels can cause a series of stages in the evolution of multicellular animals.

Let me emphasize that, since the nervous system is an organ set up by the biological behavior guidance system of multicellular animals, the stages caused by levels of neurological organization are quite different from stages caused by levels of biological organization. Neurological levels do not require a new biological behavior guidance system to coordinate the behavior of the lower level organisms, because the parts are neurons or systems of neurons and their behavior is already coordinated by the multicellular biological behavior guidance system. That is what enables them to guide the behavior of the animal.

Though there are as many as seven levels of neurological organization, the last three also depend on a higher level of part-whole complexity in the biological series as well. The level of biological organization above multicellular animals will be called the “social” level, and as we shall see, when the nervous system is used as a biological behavior guidance system to coordinate the behavior of the multicellular animals, what evolves are a kind of organism that will be called a “spiritual animal.”

Three of the levels of neurological organization occur only in spiritual animals, and thus, there is an important difference between two parts of that series of levels, the levels of neurological organization in multicellular animal behavior guidance systems and the levels of neurological organization in spiritual animal behavior guidance systems.

In order to keep these levels of organization straight and to provide a map of the overall course of evolution, all the relevant levels of part-whole complexity are catalogued here. And before tracing the individual stages, I will look ahead to what spatiomaterialism implies about the evolutionary stages involve in each series of levels of organization. 

Levels of biological organization. The levels of biological organization involve a series of levels of part-whole complexity of the basic kind sketched above, that is, levels of part-whole complexity in primary structures. In each case, the organisms that evolve at one stage of evolution are the structural causes that are bundled together as a higher level organism that begins the next stage, and what evolves at the higher level is a mechanism that coordinates their behavior, including their reproduction.

Proto-organismic level: RNA molecules. The “organisms” on the lowest level of biological organization are RNA molecules. The structural causes bundled together in them are (or at least include) the triplets of four different kinds of nucleotides that have become the so-called genetic code. Such parts are organized (bonded by a sugar and phosphate backbone) as an RNA molecule, and that chain of links is all that “coordinates” the behavior of these simplest organisms to generate both the reproductive and non-reproductive work that is required to go through reproductive cycles.

The RNA molecule can reproduce as a whole by a two stage process in which each nucleotide attracts a complementary nucleotide so that the complements become bound as parts of a second RNA molecule, and then the same process occurring in the second RNA molecules results in an RNA molecule like the original.

The distinctive structural global regularity that each such unit of the genetic code generates (that is, its non-reproductive work) is to help prescribe which kind of amino acid would be added to the protein molecule being synthesized (by a peptide bond linking them all in a chain of amino acids).

Though RNA molecules satisfy our definition of the kind of material structure that goes through reproductive cycles, that is, a primary structure, it is something of a stretch to think of them as organisms. But as we shall see, there is indeed a way, in a spatiomaterial world like ours, in which RNA molecules would inevitably go through regular cycles in which they generate both kinds of structural global regularities (reproduction and the non-reproductive work of directing the synthesis of proteins). They start out simple, uniform and weak, but gradual evolution by reproductive causation would make them complex, diverse and powerful. The most important power that would evolve during the first stage would be a reliable and efficient way of synthesizing protein molecules (the molecular machines by which traits in all living organisms are generated).

Prokaryotic level: DNA molecules. The minimal organisms at the second level of biological organization are DNA molecules. The structural causes bundled together in them as a higher level “organism” are the organisms (or primary structures) from the lower level, and once again, being linked together as parts of the same macromolecule is all that coordinates their behavior at first. Instead of being made up of RNA molecules, DNA molecules are made up of variants on them, called genes (with a substitution for one of the four kinds of nucleotides used in RNA and a slightly different sugar and phosphate backbone). Each DNA molecule is actually two strands of complementary nucleotides that are most stable when attached to one another, forming the now famous “double helix” structure. But they have both kinds of structural effects that are essential to primary structures, reproduction and non-reproductive work of various kinds.

DNA molecules can reproduce as a whole in much the same way as RNA molecules (though the two complementary strands must unzip and reproduction requires the assistance of a certain protein molecule).

The structural causes bundled together in them are called “genes,” and each gene does its non-reproductive work in much the same way as the RNA molecule as a whole. But since the RNA structures are contained as segments of a DNA molecule, each segment must first be transcribed as a messenger-RNA molecule (mRNA) and only then can it use the highly reliable process inherited from the first stage of evolution (requiring the use of ribosomes and transfer-RNA) to synthesize a certain kind of protein.

Though at first the behavior of these RNA level organisms is coordinated merely by being parts of a single DNA molecule, new mechanisms of coordination are added with the evolution of proteins that are able to repress, promote and de-repress the transcription of specific mRNA from specific segments. As products of a radical random variation, DNA molecules would have to start out simple, uniform and weak. But since there is, as we shall see, a way in which DNA molecules would inevitably go through entire reproductive cycles, their population growth would eventually make resources scarce and natural selection would be imposed. As they became complex, diverse and powerful, DNA molecules would eventually surround themselves by cell walls, controlling the behavior of their lower level organisms more completely, and eventually, as we shall see, there would come a point at which it would be obvious that life had begun. Extant remnants of this stage are prokaryotic cells, such as bacteria, cyanobacteria and archeabacteria.

Eukaryotic level: the nucleus. The minimal organisms at the third level of biological organization are cells with a nucleus, for the structural causes that are bundled together in them are organisms from the next lower level or their equivalent (that is, DNA level primary structures). Indeed, lower level organisms are bundled together in two ways, first, as multiple chromosomes in the nucleus, and second, in most kinds of nucleated cells, as organelles in their cytoplasm, either both mitochondria and chloroplasts (in plant-like cells) or just mitochondria (in animal-like cells). Though the organelles are basically just stripped down prokaryotic cells whose behavior is controlled by the eukaryotic cell, the nucleus is a new mechanism for coordinating the behavior of the DNA molecules in chromosomes (that is, a new biological behavior guidance system), and it generates both kinds of behavior that are essential for a reproductive cycle.

Mitochondria and chloroplasts reproduce themselves in the cytoplasm, but the chromosomes are reproduced in an elaborate process including the entire nucleus, though in both cases it basically is just a form of DNA reproduction from the previous level. We will consider how such a complex mechanism as the nucleus could evolve from prokaryotes.

The nucleus is a mechanism for coordinating the expression of genes on a number of different chromosomes at once, and thus, the cell does non-reproductive work by marshaling an army of non-reproductive structural effects of many lower level organisms (each transcribing various mRNA molecules which then guide the synthesis of proteins). And under the direction of the cell, the self-reproducing organelles generate non-reproductive secondary effects in the same way as prokaryotes.

Since eukaryotes come to exist as a radical random variation on prokaryotes late in their stage of gradual evolution, eukaryotes start out simple, uniform and weak. But as they impose natural selection on themselves by their own reproduction, they become complex, diverse and powerful. Perhaps the most significant contribution to subsequent evolution is the evolution of a process of sexually mixing chromosomes during reproduction. The speed of evolutionary change is accelerated by routinely shuffling lower level primary structures, if only because that makes it possible to combine in a single organism new powers for controlling relevant conditions that were acquired by different organisms in previous generations. But the evolution of sexual reproduction also makes the death of individual organisms inevitable.

Multicellular level: the mechanism of embryological development. The organisms at the next level of biological organization are so obviously made up of organisms from the previous level that it has given them their name. No one doubts that multicellular organisms evolved from single-celled eukaryotes, called “protists,” though multicellular organization is basically different in plants and animals and it evolved many times in plants.

Reproduction in this case usually comes, however, not from all the parts reproducing as parts of the whole (though such asexual reproduction is possible in multicellular plants and many simpler multicellular animals), but by sexual reproduction of egg cells followed by their asexual reproduction. The behavior of the daughter cells can be coordinated by their exchanging messenger molecules (hormones), though in animals, it also involves a mechanism of embryological development that determines daughter cells so that they also move around relative to one another in order to set up the structure of the animal body.

Multicellular organisms do the non-reproductive work of controlling relevant conditions by coordinating the non-reproductive structural effects of its member cells. Such coordination also depends on the exchange of messenger molecules, though in multicellular animals, there is a special organ of cells, the nervous system, for coordinating the cells involved in generating behavior directed at other objects in space.

Originating as radical random variations, multicellular organisms start off simple, uniform and weak, and we have seen how gradual evolution would make them complex, diverse and powerful. The most spectacular product at this level of biological organization is animals with all of the levels of neurological organization mentioned below, for that makes a new kind of animal possible at the social level of biological organization.

Social organisms: language. The most obvious way in which there is a higher level of part-whole complexity than multicellular organisms in the biological series are insect colonies. But there are other examples of colonial animals, such as hydrozoa and blind mole rats, not to mention plants, such as aspen trees, in which whole groves reproduce like multicellular plants. Insect colonies are, as we shall see, an anomalous kind of animal, because they use the same mechanism to coordinate the behavior of multicellular animals as parts of a social level organism that multicellular animals use to coordinate their cells.

That is, insect colonies reproduce as a whole, with a queen having offspring that population the whole colony, and the behavior of different members of the colony is controlled by the exchange messenger molecules called “pheromones.”

But colonial animals are not the only kinds of organisms on the “social” level of biological organization. Another and more distinctive example is human society, and its way of coordinating multicellular animals is language, which depends on the prior evolution of all the levels of neurological organization. The spiritual animal is, as we shall see, a unique level of organization. Among other things, the same, language-based behavior guidance system is both a social level biological behavior guidance system and the new kind of animal behavior guidance system that is made possible by the social level of biological organization.

Levels of neurological organization. The other way that multicellular animals lead to a further series of evolutionary stages is less radical, because it does not involve levels of part-whole complexity in primary structures, that is, in complex material structures that reproduce themselves like organisms. Instead, the structural causes that are bundled together as material structures at a series of levels of part-whole complexity occur within the structure of a single organ of multicellular animals, the nervous system, whose function is to guide animal behavior. The elementary structural causes in this case are neurons, and they behave by “firing” (that is, sending an action potential along its long axon to other neurons affecting whether they fire). The higher levels of part-whole complexity are mechanisms made of many neurons, mechanisms made of many such mechanism, etc.

The levels of neurological organization are basically different from levels of biological organization, because it is not necessary for the new level of organization to coordinate the behavior of its own parts, and certainly not to coordinate their reproduction. That would be required, if it were a biological behavior guidance system. But in this case, the higher level structures is an animal behavior guidance system. What coordinates the behavior of neurons in setting up the nervous system is the mechanism of embryological development, and though neurons do reproduce in that process, the higher level neuronal structures do not. Since the structure of the nervous system is provided for it, the animal behavior guidance system can use that structure as an ontological cause, that is, as a machine, to guide the behavior of the whole animal in acting on other objects in space.

Behavior guidance depends on another kind of behavior distinctive of neurons, namely, “firing” (that is, sending an action potential along its long axon to other neurons affecting whether they fire). Neurons are organized into higher levels of part-whole complexity when the firings of certain neurons in entire groups affects the firings of other groups of neurons, or systems of such groups affect other such systems, etc.

It is not necessary for the relevant material structures at each level of neurological organization to go through reproductive cycles on their own in order to become naturally perfect in the sense of doing the most with the least like perfectly efficient machines, because their gradual evolution in the direction of maximum holistic power is the effect of reproductive causation on the multicellular animals of which they are part.

Whatever their level of neurological organization, such material structures serve specific functions in guiding animal behavior and, at each level of neurological organization, the material structures are shaped to be as powerful as possible in controlling some relevant condition with the fewest and simplest neurons. If, therefore, a series of levels of part-whole complexity were possible in the nervous system, it would generate another series of evolutionary stages during the stage at which multicellular organisms evolve.

The series of levels of neurological organization are divided into two distinct series, because after a certain point in the evolution of the brain, higher levels of neurological organization depend on a higher level of biological organization as well, that is, the evolution of a new kind of animal at the social level. I will, therefore, list the two series of levels of neurological organization separately.

Animal levels of neurological organization. The first series of evolutionary stages caused by levels of neurological organization occurs in multicellular animals whose evolution depends only on natural selection at the level of individual animals.

Somatosensory animals. Somatosensory animals are the simplest multicellular animals, including hydra and sea stars, which interact with other object in space only by contact. In the, single neurons (and their firings) serve the three basic subfunctions in guiding animal behavior: (1) registering sensory input, (2) selecting how to behave, and (3) generating motor output. Such nervous systems are not centralized.

Telesensory animals. Telesensory animals are the simplest animals that can sense objects at a distance from their bodies, and in them, systems of neurons (at least ganglia or two dimensional arrays of neurons in the neural tubes of vertebrates ) serve the three basic subfunctions in guiding animal behavior. The eye’s retina, for example, requires many neurons working together to generate an image of objects at a distance, and locomotion in relation to a distant object requires a system of many neurons to send motor commands simultaneously to all parts of the body. Such centralized nervous systems are found in all the vertebrates mentioned above, from fish to birds, as well as most kinds of invertebrate animals, such as worms, mollusks, insects. “Telesensory animals,” as I will call them, see the whole world around them as the object on which their behavior might act.

Subjective animals. Subjective animals are animals with spatial imagination, namely, mammals. In them complete circuits of systems of neurons serve each of the basic subfunctions in guiding animal behavior (registering sensory input, selecting how to behave, and generating behavior). The distinctive mammalian neocortex marks the shift of behavior guidance responsibilities from the midbrain and hindbrain to nervous mechanisms in the vertebrate forebrain, and as we shall see, by using one circuit of systems of neurons to register sensory input (as the “local image”) and another such circuit to generate bodily behavior, including locomotion (as the “body image”), mammals have evolved a faculty of spatial imagination that enables them to think coherently about how locomotion (and motion) affect the relations of objects in space.

Motor commands can be generated in the “body image” with their effects on the actual body suspended. Such “covert locomotion” calls up memory images of what was previously perceived in the same situations in the “local image,” and so the mammal is able to imagine how certain kinds of locomotion would change the spatial relations of objects in space before acting overtly.

Spatial imagination makes both their own body and other objects in space appear to them as a natural world, and thus, such animals will be called “subjective animals.” Since they have a conception of space, they see the object as located in space and they can understand the effects of motion on spatial relations.

Manipulative animals. The best, if not only, example of manipulative animals are higher primates. A yet higher level of part-whole complexity in neural mechanisms gives them a faculty of structural imagination for thinking about the geometrical structures of objects in space and how they change as a result of manipulation. In addition to the interaction of the “body image” and “local image” circuits that gives mammals generally spatial imagination, each hand must have a comparable system in which a “hand image” interacts with an “object image” to represent the effects of manipulation on the object. Structural imagination is contained within spatial imagination so that the object being handled is seen as located in the subjective animal’s conception of space. With four hands and a body, there are five sets of interacting circuits in the primate brains, giving what I will call “manipulative animals” a yet higher level of neurological organization than subjective animals. They see the object in space as having a geometrical structure.

Spiritual levels of neurological organization. The series of levels of neurological organization in multicellular animals continues in animals that become parts “spiritual animals.” Multicellular animals are the lower level organisms that get bundled together as parts of a higher level organism that goes through reproductive cycles as a whole, on the social level of biological organization. But spiritual animals are radically different from insect colonies, the other social level animals mentioned above, because instead of using the mechanism of embryological development (the biological behavior guidance system from the multicellular level) to coordinate the behavior of the constituent multicellular level organisms, the spiritual animal uses a basically new mechanism, namely, language. The use of language serves both as a biological behavior guidance system  (coordinating the behavior of lower level organisms as parts of a higher level organism that goes through reproductive cycles as a whole) and as an animal behavior guidance system (guiding its behavior like an animal at the social level of biological organization). That makes this social level animal unique, and since it has no body except the independently moving bodies of its biological parts, it is aptly called a “spiritual animal.”

The use of language requires, however, a level of neurological organization higher than that of primates. Because of that function, the levels of neurological organization are evident in levels of part-whole complexity in the structures of the linguistic representations they use to coordinate behavior.

Primitive spiritual animals. Linguistic representations at the level of “natural sentences,” with a simple subject-predicate grammar, make it possible to coordinate behavior in nomadic groups of primates, called “hominids.”

A higher level of neurological organization is required for the capacity to generate and understand natural sentences, because not only must covert manipulative behavior be able to combine multiple object images as representations of states of objects in space, but the animal must also be able to generate (and understand) verbal behavior that indicates the kinds of covert behavior involved in constructing the natural representation. That is, linguistic behavior has both a verbal and a nonverbal side.

Such a brain mechanism can serve as a spiritual behavior guidance system, because when a leader assigns different tasks to different members in a public process, not only does each member know what he is supposed to do in a plan of group action, but all the members know what everyone is supposed to do. The same plan of group action is then contained in each of the brains of the members. That is how their behavior can be coordinated in attaining a single goal.

The spiritual animal has both kinds of structural effects required to go through reproductive cycles as a whole on the social level.

The spiritual animal behaves like a manipulative animal at the social level, that is, with each member acting like a distinct hand in concert with the others as part of a common plan for acting on objects in space.

But such spiritual animals can also reproduce as a whole, because the members can all reproduce sexually at the individual level and, when its population becomes too large, the nomadic band can divide into groups that go different ways.

Thus, spiritual animals multiply in space, make resources scarce, and thereby impose natural selection on themselves, so that they evolve by reproductive causation toward natural perfection of organisms of their kind.

Rational spiritual animals. Linguistic representations at the level of “psychological sentences” make subjective animals reflective, and that gives spiritual animals and their members the power of reason.

Psychological sentences take words referring to subjective animals (or spiritual animals) as their grammatical subjects and predicate of them verbs of propositional attitude, such as “perceive,” “believe,” “desire,” and “intend,” followed by a sentence indicating the proposition to which the attitude is taken. Psychological sentences are able to represent the causes of behavior (and beliefs) in subjective animals, and the use psychological sentence makes linguistic animals reflective, because it enables them to use the functioning of their own brains to imagine the behavior guidance processes going on in other brains. They are eventually able to use psychological sentences to represent the causes of their own behavior (and beliefs) as causes in the very process of causing that behavior (or belief), and since that affords a new, reflective level of control over brain processes and the behavior it generates, the causes come to be called “reasons.” Thus, the use of psychological sentences eventually leads to reason.

At this level of linguistic (that is, neurological) organization, not only is language used by a leader to assign tasks, but the linguistic representations exchanged among members of the spiritual animal have the structure of arguments, that is, conclusions about what to do (or believe) together with a reason for them. Thus, in addition to making both the individual and the spiritual animal more powerful, the use of psychological sentences is the foundation for a new form of evolution by reproductive causation to take place, namely, cultural evolution.

In this case, the “organisms” are arguments (with the component sentences serving as the structural causes bundled together in them). The non-reproductive structural effect of argument is to guide behavior (or beliefs). Arguments reproduce when one member convinces another to accept it. Arguments impose natural selection on themselves because the brains into which they can reproduce are finite. And which arguments succeed in reproducing is not just chance, because individuals can judge which among competing arguments is most coherent, given everything they know. Hence, arguments are subject to rational selection and tend to evolve.

Thus, at the rational spiritual level of neurological organization, there is an evolution of the arguments accumulated as the cultures of spiritual animals, and as we shall see, it is change in the direction of natural perfection for arguments (or reason). Arguments have maximum holistic power for “organisms” of their kind when they discover the true and the good.

Philosophical spiritual animals. Linguistic representations at the level of philosophical arguments lead to a step-like increase in the power of reason to discover the true and the good. Philosophical arguments are a higher level of part-whole complexity in linguistic representations, because philosophy uses a foundation to defend more fundamental truths about the world. In one way or another, philosophical arguments try to explain why the other arguments that have accumulated in the culture of rational spiritual animals are valid, ands that gives philosophy a higher level of forensic organization.

There are, as we have seen, two, basically different ways of making such a higher level argument, epistemological philosophy and ontological philosophy. Epistemological philosophy uses a theory about the nature of reason that comes from reflecting on how rational beings like us know to prove that certain ordinary conclusions about the true and the good are correct (or false). Ontological philosophy uses an empirically justified ontological explanation of the world as its foundation for explaining the validity of the ordinary arguments of the rational spiritual level. (Though that leads to an explanation of the nature of reason, its explanation of the nature of reason is not the foundation of ontological philosophy, but just one of its implications.)

The simplest and most natural way to construct such a higher level argument is the ontological approach, but it cannot succeed until natural science has evolved. Thus, the first approach to philosophy to prosper for long is the epistemological approach, and though it inevitably fails on its own (mainly because of how realism leads to ontological dualism and dualism leads skepticism), it gives rise to natural science, eventually making it possible for ontological philosophy to succeed.

There are, therefore, two phases in the evolution of philosophical spiritual animals. They do not reach the maximum holistic power for “organisms” of their kind until ontological philosophy succeeds in making the fullest use of this level of neurological organization.

Though philosophical arguments do not require any change in the brain structures set up by the mechanism of embryological development, they do involve the acquisition of a higher level of neurological organization in the individual brain. But it comes from process of learning language and the arguments that have been accumulated as culture.

However, there is yet another kind of series of stages in the evolution of spiritual animal, because there are levels of part-whole complexity in the social structures (as opposed to cultural structures) of spiritual animals. Among them there is, in addition to cultural evolution, another form of reproductive causation at work on “organisms” constituted by evolved structures (including the evolution of class structure and eventually capitalism, which is a third form of reproductive causation that takes place on the social level). The combination of these various stages of evolution entail a philosophy of history in the 19th Century style. But I will leave those evolutionary stages and their complications for the next section, when we trace the course of evolution through all of its stages in detail, from its beginning through the history that still lies in the future.