Any theory of behavior claiming to be correct must include a correct theory of knowledge. In view of the modern debates this is crucial. Theories such as evolutionary psychology tell us that our evolutionary ancestry shapes our thinking. Only this creates a paradox, because how can we know that evolution does not shape our thinking to an extent that we can never discover the correct theory of how we think at all?

Fortunately, humankind has encountered this type of paradox before. It happens that all our scientific laws depend on measurements to prove them true. Yet we can only formulate these laws after we take the measurements, which is a paradox. We resolve this by learning from experiments that do not depend on an absolute measurement of a quantity but only a relative result. The Michelson-Morely experiment, which examined the alteration in the speed of light against its position in space was an experiment in this class. Because the result was only a relative measurement, the result itself was a law not dependent on measurements. Einstein used this principle to formulate the Theory of Relativity

Discovering laws of mind, brain, and intelligence presents a problem akin to discovering the Theory of Relativity. We wish to measure, scientifically, how the brain evolved and how it functions. But the ultimate device for interpreting the results of those measurements is the brain itself. So before we can discover how the brain works, we must have confidence that it works reliably. Especially, before we can be certain we have arrived at the correct theory of how the brain evolved, we must review first whether the brain can distinguish any properties of the universe that would be true regardless of how the brain evolved. Plus we want to know two things, very important, about the brain.

1. Why did the human brain evolve into the size and structure that it reached? We could have survived with a much smaller brain. So, why on the savanna did the brain evolve at great fitness cost to be a much larger one than needed for primitive life?
2. Is the modern human brain a reliable devise for assimilating knowledge? The brain evolved into a particular size and structure then it stopped evolving. How do we know that when it stopped evolving, driven only by primitive survival needs, it was a sufficiently evolved brain for civilized life?

The Theory of Options provides a new framework for answering these two questions, despite that prior to this the answers proved very difficult.

Both answers concern that humans were evolving along a pathway of maximizing the options of behavior. Pre-humans might have been able to survive on the savanna with a smaller brain, but if that brain did not maximize the options of behavior the pathway along which humans were evolving had not yet reached its end point. At an intermediate plateau of human evolution a smaller size brain would have been optimal for life on the savanna, and human evolution did stabilize on intermediate plateaus for long periods. But human evolution was not adapting for life on the savanna or any environment. After all, human sub-varieties migrated first over Africa, and later to Asia. So no matter which plateau of brain size or intelligence human evolution might temporarily halt at new individuals with larger brains were being selected. Selection would first be among individuals within groups. But as groups grew too large they would split on behavioral lines. Over time less resourceful and less intelligent sub-groups would be wiped out. Only while the process of splitting into groups occurs among other primates, it becomes unique once intelligence is involved. A less intelligent monkey can adapt its entire biology to a niche more intelligent monkeys might not adapt to. But there exists nowhere on Earth a forest, plain, valley or mountain where a more intelligent hominid could not adapt better than a less intelligent one. So, the competition keeps going until a group evolves with a brain for which there can be no further significant improvement.

But what was the end point of that competition? What was so special about the size and structure of the Homo sapiens brain that once it evolved humans quickly displaced all other hominid types?

We must be careful here. The pattern of human evolution was for types to evolve within an area in Africa, then radiate once the evolved feature reached maturity. Some critics dispute it, but generally populations have to be small to evolve so that new novelties can sweep to fixation among them. Once a population radiates over the Earth without pockets of it becoming reproductively isolated it looses its mechanism of species-wide evolution. So, hominid types with smaller brains such erectus still had a brain sufficiently versatile that the species could radiate, only the radiation was premature. In fact a brain sufficiently large for migration but not maximally large turned out to be a trap. Once a new group evolved with a still larger brain it too could radiate, but by then the widely dispersed earlier species, such as happened to erectus, had no evolutionary mechanism left with which to compete. By these successive waves of evolution in a small area in Africa, then radiation of the matured species over the face of the globe, Nature was able to evolve the human brain by an effective optimal search. From Africa, types with bigger brains continued evolving and then radiating until a universally adaptable type was found, which could not be displaced by any further evolution and radiation.

Still, in evolution there are always two fitness pressures, one driving change and the other resisting it. Although there was selection pressure to evolve a brain to a certain size other restraints would stop it evolving beyond that size once optimum was reached. While larger brains than the human one are also possible, beyond a certain size the evolutionary cost of evolving the brain further could not return an advantage over other ways to use the brain. Plus fitness is always inclusive. Selective pressure was to be intelligent, but not genius. Humans also have to be strong, brave, and caring. The minimum intelligence an individual needs to be inclusively fit is not the maximum intelligence possible. We see this today. A person with below normal intelligence falls behind, but average can still do well.

So, humans evolved a brain that maximized the options of behavior but only as inclusive fitness of all things that humans do. Plus as brains grow larger advantages multiply for the group. Brains evolve because of individual fitness, yet once the group can survive most hazards because all its members are intelligent selective pressure to evolve further intelligence will diminish. Suppose that above a minimum size brains can use language. Then once it can use language a group has many ways to compete, apart from by individuals evolving bigger brains. From when language emerged it might take another 10,000 generations to evolve a significantly larger brain. But in fewer generations humans could build computers and land on the Moon with the brain they already had. We do not know precisely that it was language marking a point of fitness saturation for evolving a larger brain. Just an optimal search is always along a pathway. It continues in fits and starts along the path until optimum is reached, then it stabilizes.

Except all previous evolutionary pathways were for adapting to a unique environment or niche. Humans were adapting to maximizing the options of behavior. So how do we define such a pathway end point in terms of intelligence or brain size? How do we know that an average 1100 cc brain, or whatever it was, does not maximize options of behavior, but a 1450 cc brain does?

The answer is controversial. We do not know if the brain is optimal one because of its capacity, organizational structure, or sophisticated sensory input-output like vision and language. Yet we know how to maximize the options of knowledge once acquired, and it is one of the few truths that we know for certain. Interestingly, before philosophers worked it out, Nature too discovered how to maximize the options of knowledge, by a search for optimal fitness on the ancient savanna. Crudely, advanced primates like chimps, though some say all higher mammals, can abstract slightly. Except abstraction carries fitness dangers so it only evolves as far along a pathway as needed to adapt to an environment. Then the pathway closes. But humans were evolving down an open pathway. So, we need to know far down an open evolutionary pathway selection will push abstraction, to maximize the options of behavior and knowledge.

It is like asking which covering of body fur offers the most options for climate adaptation. If other means can be found to keep warm, a body devoid of fur offers the most options. Humans have a ratio of abstraction to reflex that would be dangerous to instinctual survival. But if other means can be found to alleviate these dangers the optimum amount of abstraction is to be able to totally "abstract" thinking from reflex. Out on the savanna a primitive hominid does not need to recite the Iliad or understand quantum gravity. But if his line does not evolve a brain that can abstract thinking from reflex, it will be replaced in the struggle for survival by a hominid line that can. Again, there are costs to evolving a large brain, but many of these seem to be in the birth process, rather than the neurology. Perhaps once the brain evolves to a certain size say 1,100cc average, most of the evolutionary costs are paid already. If full abstraction requires a few hundred more cc of cranial capacity to reach it, at least one line will search out this evolutionary option, because the pathway stays open until the maximal state is found. If there is a low evolutionary cost to evolving the last few hundred cc this is more why the brain evolved so fast. Once a species is maximizing the options of behavior along an open pathway it eventually will evolve a brain that can fully abstract. The detail is in how long it takes to get there.

Still, even with our already large brain, we might find the above argument difficult to follow. A crucial objection in all such explanations is that fitness only accumulates for individuals, but the products of mental abstraction mostly benefit groups. So we must explain why, in the primitive struggle for life an individual with a brain capable of abstraction or imagination will pass more of his or her unique DNA into subsequent generations than a rival. We must remember that every biological enhancement comes at a cost. For the same cost of evolving abstraction in the brain, another individual might evolve greater instinct, or another greater strength. This is why other animals do not evolve larger brains, though another reason is that humans did it first. All any organism needs in its brain is information vital to its survival. Other data serves no purpose while the extra neural machinery would penalize fitness somewhere else. This is why it is now popular to assume that large brains evolved for incidental reasons, such as a useful courtship device to attract and retain sexual mates, or to stimulate and entertain people. The argument is that once one individual can stimulate and entertain others must do so to compete, in a runaway peacock's tail affect, as given in the quote by Geoffrey Miller. This explanation might seem desperate, but it does at least account for individual fitness.

The problem might be that because large brains are imaginative, we are trying to find a fitness advantage for so much imagination. It is like 30 years ago trying to find a justification for the putting the equivalent of a supercomputer into everybody's home. Or if finding today that such computers are mainly used for playing games, wondering why humans pushed such an advanced technology just to play games. What happened in technology was that for reasons which might not be clear if one did not know the history, it suddenly became cheap to build powerful computers. What else happened was that once the price fell within an affordable range, people preferred the most powerful computer that they could buy for the small incremental cost of owning one. This is what we explain repeatedly throughout this thesis. When each neural circuit has to be designed by selection neural power is horrendously expensive, so it increases slowly never growing faster than other changes of morphology. But once the highly flexible learning circuits of the upper cortex are perfected, neural circuits can be mass produced in great quantity, and programmed after birth. It would not make any sense at all to push a supercomputer into every home just to play some silly games if computers were still manufactured the way they were 30 years ago. And it would not make evolutionary sense to provide humans an over large, imaginative brain, if each neural circuit has to be painstakingly crafted by selection. But humans evolved when an extra billion neural circuits came at a low genetic cost of circuit design, even though there were other high costs in large brain mass. So like with computers, we need to understand the evolution of the brain in the terms of technology available.

The other point is that if there were not some other selective pressure driving it, species would not have kept migrating from Africa. Some force in Africa meant that even fully erect, versatile tool-making hominids with moderately large brains like erectus were still being pushed out from the center. We must assume that they were being pushed away by creatures with still larger brains that could better compete. Only again, whether it will be used for gossiping about sex, attracting mates, or competing for food, the fastest way to evolve a large brain quickly at the least fitness cost is by multiplying those neural circuits with the greatest generality of use. The flaw in Miller's theory is not his hypothesis about using the brain for courtship, but his assumption that the neurology was selected to be content specific towards gossip or entertainment. The brain evolved quickly and in competition for whatever reason. But the part of the brain that was greatly multiplied in the higher and frontal cortex was general-purpose neural circuits with a very high ratio of postnatal learning. These are the circuits which, because they could be wired after birth, they could be multiplied rapidly from a few genetic instructions without prolonged fitness selection for the wring of each circuit over time. Neural circuits that are wired postnatal, have a very high learning ration, are general purpose, and do form a large, homogenous mass of newly evolved neurology easily subtend to imagination and abstraction.

So, under the prevailing conditions of struggle it was fit for individuals to evolve a large brain quickly. Only large brains that evolve quickly are also imaginative brains, which can often produce unfit behaviors, such as fantasy, illusions, traumas, and irrational beliefs.

Moreover, even if Miller's peacock's tail theory or similar could explain why the brain is large, these theories must still form in the brain. And they form in a brain that ceased significant evolution 35,000 years ago, as the brain of tribal, Stone Age hunter-gatherers, but not the brain of a civilized, technically advanced race. Except for modern humans this brain is the inaugural intelligence device. For the human eye we can enhance its vision with radar, microscopes, or telescopes, so only we need be certain that eyes provide for normal vision a 100% accurate image of reality. Similarly, we can enhance the reasoning power of the brain by mathematics and computers, and can enhance its moral powers by laws or ethics. Only we are dependent on the brain for the inaugural perception of reality. If the hunter-gatherer brain did not solve the problem of inaugural perception, then subsequent enhancements to intelligence will be in vain, and human knowledge will be ultimately founded on illusion.

Fortunately again, inquiry into the native reliability of the human brain is not new. Long before evolutionary psychology, philosophers recognized that though the human brain was unique it was also imperfect. People imagined things, cultivated illusions, or held unlikely beliefs. So, philosophers concluded that ideas could not be accepted prima facie (as it first seems) but that every proposition must be scrutinized by reason. Philosophers were confident that reason was true prima facie because through symbolic languages like mathematics reason had demonstrable methods of proof, such as the angles of a triangle summing to two right angles can be demonstrated by measurement. These ideas existed since antiquity, but great French philosopher-mathematician René Descartes (1596-1650) formalized them in a view known as dualism. Descartes is best remembered for splitting off mind from matter, by insisting that whereas physical activity was a property of any machine, mental activity could only belong to a soul. This split strikes us as peculiar today, not just because few of us believe in souls, but because machines that now perform mental tasks or convert electronic information into mechanical actions are commonplace. Yet the significant contribution of Descartes, often overlooked in modern criticism, is that he realized that certain thoughts such as those expressing mathematics would be true regardless of "whether I am awake or asleep" providing only that they were free of logical contradiction. These thoughts implicitly true within themselves could be the basis of all other tests of truth.

Only no sooner had Descartes resolved this than a baffling problem arose. As the scientific-industrial age progressed many rational conjectures of earlier times such that planets moved in circles, were discovered false by new observations. Planets move in ellipses, not circles. Particularly, Euclidean Geometry, once regarded as a perfection of rational thought, was discovered to little describe the world as it existed. If we consider measurements on the scale of the universe it is not conclusive prima facie that angles of a triangle will sum to two right angles, or that parallel lines never meet, and so on. It seemed that while mathematics could prove that a class of thoughts could be free of contradiction within itself, the unique gift of rationality was proving misleading, even for the most brilliant conjectures.

The English philosopher John Locke (1632-1704) solved part of the problem. Because he believed that reason alone was perfectible, Descartes did not trust the senses. But Locke demonstrated that all thoughts impinging on the mind, even imaginative ones, arose from impressions first existing in the senses. Crudely, an image of a mermaid is conjured from the impression of a fish and a woman. So, any reliable information in the brain must also come from the senses as could be demonstrated by the need to observe that planets moved in ellipses, not circles. Yet, if all information came from the senses how could the brain conceive perfectible ideas like those of geometry, if those ideas had no natural physical basis? This problem was solved by another Englishman, or Scotsman, David Hume (1711-1776). Hume demonstrated that all impressions in the "thinking" part of the brain we now term the higher cortex are nothing but imagination. If we observe an event repeated enough times we imagine it to constitute a law of nature, while if we organize our thoughts symbolically, as in mathematics, we discover which thoughts avoid the logical condition of self-contradiction. But even laws are only an image of how nature behaves. Our senses gather data, but placing data into a logical picture of reality is performed in the imaginative part of the brain, not within the more reliable circuits of reflex.

Still, if we follow this rationalistic view of the brain we also end up with a dualism, but of types of knowledge rather than the original split of mind from matter. Roughly, we break knowledge into two branches;

1. Analytical truths, which are proven by a system of symbolic manipulation, such as mathematics or formal logic, but exist independent of experience.
2. Empirical truths, which cannot by proven by symbolic manipulation, but must in each case be verified against the evidence of the senses.

Now there are strong objections to splitting knowledge this way. Firstly, while the dualism is not of the type proposed by Descartes between mind and matter, any split-up of knowledge is regarded as fragmentation in an age when we should try to harmonize the resources of knowledge. Also, categorizing truths as analytical or empirical excludes moral truths, which is a serious problem. Finally, while modern neurology confirms that the recently evolved brain is imaginative while the more primitive brain is reflexive, this is not a precise split. All the neural circuits of the brain interact. They are products of the evolution of the whole brain not just parts of it, and theories that brains evolve as separate parts rather than a whole organ have not done well. Only the split of knowledge in philosophy is precise, related to the grammar of propositions but not the natural neurology of the brain. More controversially, the split is based on how philosophers stress propositions should be asserted rather than how humans naturally think. Notoriously, philosophers always tell us how we 'ought' to think and speak rather than explain how we actually do.

Yet, while the above theory of knowledge needs updating to modern needs it still assists us answer crucial questions on the evolution of the brain. Firstly, we have the circular problem of trying to understand how the brain works with our own brains as the tool of understanding. So we resolve this by noting if there exist thoughts that the brain can conceive, which would be true regardless of how the brain evolved, or how it works. Using the earlier theories we note that mathematics is a class of knowledge true independently of how the brain evolved. For example, because of how humans evolved, to our brain a monkey looks ugly but a gazelle is beautiful. Because of the way our brains evolved, we pillage our environment, without appreciating that our children will suffer for it. And because of the way our brains evolved, we believe in Gods, territory, or that our race is superior to others. But despite such thoughts of the brain being evolution-specific, humans as a species seem good at math. In any civilized age humans learnt more math than they could practically apply, and there have been many clever mathematicians. Children enjoy math, and most humans seem to have a natural grasp of ballistics and quantity. Chimps have the brain of a 1-3 year old child. Yet, it is beyond this age that humans start to grasp math. And it is not just that humans are good at math, but for math we have other arguments that its truths are independent of how the brain evolved. We could say, exchange mathematical knowledge with beings from another civilization by radio, knowing nothing about their biology, how their senses worked, or how or why they evolved.

That the brain can grasp concepts that are true regardless of how brains evolved gives us confidence that the brain can also understand how brains work. Only this might not prove that this is a maximally adapted brain, unless we can prove that separating abstraction from reflex maximizes the options of thinking. Again, based on the conclusions of analytical philosophy it seems that it might. The proofs are somewhat tedious, but roughly, abstraction provides a general case, which offers the maximum flexibility. If 2 + 4 = 6 we can prove a general case of n + 2n = 3n or n(1 + 2) = n(3) which is a higher form of abstraction yielding more general truths. But also we have learnt through science that abstraction must be tested against the evidence of the senses, and this evidence must be free from the influence of abstraction. This will offer maximum options because it allows us to alter thinking in the face of fresh evidence. Only this requires that there must be a split in mind between cause-and-effect as it exists in the physical world outside of mind, and the way that events appear to us in mental imagery.

Splitting thinking into separate tasks of abstraction and data gathering seems to be how human brains work. Photons of light striking the retina or atoms impinging against receptor nerve endings are physical cause-and-effect. Once these pass through data gathering circuits of reflex, they are assembled as images in the higher cortex by psychological association. All brains, not just human ones, work in this manner, with part of the neurology for gathering data of cause-and-effect, and another part assembling this information as thoughts and images. Only Hume claimed that in the human mind there is no solid connection between outside cause-and-effect and the psychological impression of it in the higher cortex. Yet, if breaking the solid connection between reflexive and reflective thought maximizes the options of thinking, it must be explained in fitness terms. Nature only selects thoughts controlled by reflex. So the higher the ratio of reflective to instinctive thoughts the less nature has selected how the brain thinks. But in humans this ratio is eight to one, or eight parts abstraction not selected by nature, to one part reflex programmed by nature. Such a high ratio of 'free' to instinctive thinking tends to support Hume. Still Darwinists remain strongly critical of Hume because evolution teaches, allegedly, that all thoughts evolve to express fitness needs. Yet there can be no apparent fitness need for analytical thinking out on the savanna, if, as Hume had contend, analytical thought is a product of the imagination, not connected to outside reality. Mathematicians complain that today they have difficulty justifying research in pure mathematics. How does one justify to Nature, on the primitive savanna, evolving a brain capable of mathematics?

Despite Darwinist objections to Hume a split in the human brain between imagination and reflex makes evolutionary sense. Human reflexes, especially for crucial functions like vision, metabolism, balance, touch, voice, and movement, are superb where reflex alone will do. But if basic reflexes function well, it is efficient evolutionary design to allow lesser reflexive functions, like those for hunting or food gathering, be more generalized. Having core reflexes optimized for the functions they perform best, but less essential circuits of the brain generalized for a variety of functions offers maximum versatility. The process by which reflex functions of the lower brain are moved to functions of the upper cortex is known as encephalization. Learning can program the imaginative elements of the brain for reflexive response, as for an athlete or hunter, or it can optimize the brain for some other function not yet considered. But the elegance of this optimization of brain function is that the most intense mental activity, analytical thinking, requires verification against the core reflexes anyway. A million years before philosophers realized that rational knowledge must be verified against evidence of the senses, Nature figured it out anyway. So, the human brain encompasses a brilliant double optimization of design by nature, offering both maximum versatility of function and expediency of construction.

Also, maximum options arise from gathering the most information about a circumstance, so all responses can be evaluated. This requires a general information gathering system for the brain while leaving the brain a mental capability to decide for itself which of the data gathered was useful or not. So intelligence might be the ability of a brain to gather more information about its surroundings than is needed for its survival and to decided for itself where, how, and to what purpose to apply the information it had gathered. The human brain enacts development from a data-gathering device into a data analyzing one, a feat not yet achievable with artificial intelligence. Yet even for a device not composed of living tissue information processing is still more efficient if the 'data gathering' and 'data analyzing' functions can be optimized to their respective areas. The brain does this efficaciously. Neural circuits for very precise reflex like metabolism or vision must have been developed over millions of years of evolution, so within the human brain these circuits become optimized around pre-existing evolutionary structure. But the multipurpose neural circuits of imagination need only be evolved once, then they can be rapidly multiplied many times by a simple genetic instruction. Because these circuits are multipurpose however, does not mean they are exclusively for imagination. If conditions demand they can form back-up circuits to reflex, which is probably what much of the pre-civilization human cortex did. Just that after civilization begins, when humankind develops science and philosophy, we discover that the analytical method to maximize knowledge conforms remarkably well with how the brain actually functions by natural design.

Modern neurology has confirmed this basic model of the brain, with a fresh look at details. Neurology directly connected to the outside world is concentrated in a more primitive, lower or middle brain (see diagram). But within the higher cortex a majority of neurons (inter-neurons) are not connected to the outside world of sense perception or motor response, but to each other. Not only are most neurons in the human brain connected to each other, but a major part of the extendible wiring of the brain is not from brain to the senses, but from the left to right hemisphere halves of the higher cortex. This creates in the brain not just reflexive thinking, but reflective thinking, in which ideas bounce back and fourth within the brain and between hemisphere halves. So though we build a picture of reality over time at any instant only 10% of our neural machinery is gathering data about the outside world, while 90% is interpreting the data. This interpretation of data will depend very much on prior psychological association, which is what Hume said.

Modern neurology, however, is more careful about custom operating upon imagination within the left-right hemisphere halves. Vivid imagination of colors, shape and fantasy appears oriented to the right cortex half, but reason, language, writing and calculation, are in the less imaginative left-cortex. Complicating the model is a view that grammatical language, writing and calculation are the real sources of reason. Yet, because grammar, writing, and mathematics occurred after emergence and as the left-hemisphere evolved as an organ millions of years before that it must have performed another pristine function, but most likely natural mechanics. Birds fly naturally, just as humans run naturally. But other motions in humans such as swimming, throwing objects, or acrobatics are learned. Only humans have a versatile mechanical brain. For living creatures humans have an inordinate interest in how mechanical objects work, and an excellent grasp of natural ballistics. So reasoning, grammar, or philosophy, might be symbolically expressed forms of natural mechanics. To correct Hume, while the human higher cortex is imaginative, left-hemisphere imagination is more oriented to solving mechanical-type problems than the pure imagination of the right hemisphere. But this is why we must be careful. Our left-hemisphere fools us into thinking we have a perfect grasp of natural mechanics, when it is nothing but that part of our imagination optimized by millions of years of evolution into solving mechanical-type problems.

If anything, the imaginative nature of the higher cortex might be another efficiency of design. Humans traditionally store information in complete assemblages in books, filing cabinets or libraries, so we assume a similar storage model for the brain. But how we view information is not an efficient way to store it. Often we view similar information slightly different ways. But if to do so we must store the entire information package in the manner in which we wish to view it this leads to the same information being stored in many different places. A more efficient way is to store information as indexed data, then assemble a "view" of the information as we need it. It is a like multiple aircraft flight simulation games. There are not dozens of aircraft models 'flying around' inside the computer. Instead, separate software modules control flight mechanics, flight data, "visuals" of what each aircraft looks like, game strategy, mission details, the terrain, and so on. Another software assembles the whole into a realistic screen image of what the player wants to see. Most likely the brain also uses dynamic assembly of information. Say an index of mechanical models of cause-and-effect might be stored in the left hemisphere, indexes of shapes and colors might be stored in the right. The images we see in our minds might in some cases be pure memory of a particularly striking incident, or they might be an "on-the-fly" assemblage of object models or data types relevant to an image we wish to conjure at the time.

Only we must caution that because the human brain is the inaugural intelligence device its functioning is how we interpret the world. We must not conclude too hastily that the brain is optimally designed because we have not encountered any other device against which we might evaluate its fitness. The brain often seems limited by our inability to grasp complex thoughts and inability to explain the thoughts to others. The brain also seems morally limited, in that few brains seem able to grasp global dilemmas of the species in anything but tribal-like terms of the brain's ancestry. Plus median intelligence only has to be above minimum for individuals to be fit. Individuals below minimum intelligence will suffer. But fitness is inclusive and above minimum intelligence an individual human does not have to be a genius. So, a brain must evolve to a point where it can abstract thinking from reflex to maximize the options of behavior. The human brain reached this point on its evolutionary pathway but it might have ceased evolving further very shortly after reaching this point, for other reasons of evolutionary dynamics.

How the brain, an organism developed solely by the natural forces of evolution has come to be an instrument of reason, imagination and abstraction is a controversial issue. The view of "evolutionary psychology" is that all thoughts in the brain must be evolutionary specific, evolved for fitness. But this view contradicts some of the few concepts we know that are true absolutely, such as the tautological nature of mathematical propositions. Yet, the correct interpretation of evolution is that only the brain as part of the total physiology must be fit, and reflexive thinking must be fit. But these fitness needs will evolve a higher brain that is imaginatively free, and this offers the maximum options of behavior. Using the new approach, we can see that the evolutionary history of the brain does match, felicitously, with other theories of human knowledge, independently derived by philosophy. These teach that all data impinging on the thought process ultimately arises from the senses, and that reason occurs, as tautology, in the imaginative function of the higher cortex. Only reason itself, with which we examine the brain, is not a product of direct evolution. The left-hemisphere of the brain does possess an evolutionary ability to assimilate mechanical knowledge better than the right half, for reasons still not clear, although they would be associated with natural mechanics such as judging speed and distance. But the ability of the brain to reason is reinforced in the modern mind by use of grammatical and symbolic language.

There should be no conflict between the theory of knowledge and how humans evolved. Once understood, we can see that the great conundrums of philosophy that have plagued mankind for millennia were already solved by nature in the emergence phase of human evolution.