All animals that can learn develop beliefs, or models, in their brains or nervous systems of the way the world seems to be, on the basis of which they do things, moment by moment, that involve predictions (expectations) of what will happen when they do those things, and most of the time this goes smoothly because those predictions turn out to be accurate enough, that is, turn out to be what actually happens. We are arbitrarily saying that each of those animals has "subjective experience," which can be observed by no one, but is, from the animal's standpoint, all that that animal is, or has to work with, and each of those animals has beliefs about that subjective experience. That is true for us humans. Each of us experiences the world in a particular way that no one else can ever observe. And we have beliefs that have arisen from such experience so far.

We humans can, however, produce within the subjective experience of others something (which we can't observe) by our learned and agreed-upon use of language (our "first exponential change"), and we can observe the "outward" reaction of others to our doing so.

We have to follow agreed-upon meanings of words and agreed-upon rules for using them in order to do this communicating. We state how we feel, what we perceive, what it means to us, etc., and others listen and react in some way. That reaction matters. As we put our Subjective Model beliefs into words, the reactions of others means something in that they will sometimes seem to agree or disagree, and if they disagree, then we begin to wonder if what we believe is actually so or not. When others say, "That's not correct," we often tend to believe there may be a problem with what we believe. This is the very beginning of "objectivity" as it is being used in this presentation.

And it is occurring because we have begun linguistically modeling (putting into words) parts of our Subjective Model of our subjective experience. As soon as we do, we are introducing an element of objectivity, because we are beginning to use agreed-upon tools to try to model our Subjective Model, and we are paying attention to the reactions of others to our presentation of it to them. Thus, rather than being satisfied with how things "seem," we are looking to others for some degree of guidance as to how things "really are." This is a process of gaining independence from subjective experience and from the further subjective modeling of (development of beliefs about) that experience, on the road to objectivity.

But just whether others agree or not is not the best we can do in the way of criteria for the legitimization of belief. (Remember that by "legitimization of belief" I mean "demonstration of appropriate and acceptable reasons for having the belief," that is, clarification of why I believe it and why I believe you should believe it.) We together, as a species, have developed the rules of logic and the rules of evidence that give us additional, agreed-upon criteria for the legitimization of belief. Doing so has, in the extreme, given us science and technology, and the absolutely amazing capability of doing what no other animals on this planet have ever been able to do, nor ourselves before this "second exponential change." But even without going to the extreme of science and technology, it is still extremely impressive the extent to which we learn from each other what the world is "really" like, including how to do things, such knowledge being far beyond what any one of us can learn only from his or her own day-to-day experience, excluding such learning from others. What we learn from others adds drastically to (and sometimes contradicts) what has seemed to us to be "true," giving us drastically improved capability with regard to certain aspects of living (but of course not all).

So the sum total of the growing, increasingly agreed-upon beliefs about (models of) the way the world is, was, and will be, as epitomized by the sciences, is what we are calling the "Objective Model," as opposed to the "Subjective Model," the sum total of all of the beliefs that each of us has built up from our own subjective experience, independent of what anyone else has to say, and active primarily in our moment-by-moment living of our daily routines, whether or not ever put into words.

So the primary source of the beliefs within the Objective Model is "being told" by others. We first learned to linguistically model our own Subjective Model, or collection of beliefs, based upon our own subjective experience, but we finally have developed our (own version of the) Objective Model primarily through linguistic modeling done by others, from whom we have learned.

But now it is time to make an even clearer distinction between these two models, the Subjective Model and (one's own version of parts of) the Objective Model.

One could metaphorically look at the Subjective Model as a large and growing mass (of beliefs), and then imagine a bump appearing on that mass. That bump (Objective Model) becomes a larger and larger mass, coming to exist alongside the first (also growing) mass, and containing only a small connection with the mass from which it differentiated. That would be one way of conceptualizing.

And it should be clear that there are not two spatially separate sets of neurons in the brain dedicated to either the Subjective Model or the Objective Model. That would be very, very unlikely. Instead, we could easily imagine that a particular neuron had some role in certain Subjective Model beliefs and also in certain Objective Model beliefs. And this idea would be consistent with our recognition that both models have to use the same material, the material of subjective experience, in their construction. Also, as we have considered before, any particular belief is interconnected with other beliefs, as for example the belief that my car is in the garage being interconnected with my belief that I have a car and a garage, and my beliefs about cars and garages in general.

So we could say that there is, in one way of looking at it, no clear dividing line between the Subjective Model and the Objective Model (in an individual).

Yet the criteria for determining whether a belief is part of the Subjective Model or part of the Objective Model are distinct. The Subjective Model is of the way things seem, whereas the Objective Model is of the way things "really are," whether they seem that way or not (recognizing that that model can of course be inaccurate).

So the crucial understanding to have is that a particular belief could be a part of either the Subjective Model, the Objective Model, or both. Your belief as to what it will feel like when you sit down in your favorite chair is most likely completely within the Subjective Model. Your beliefs as to what crystals of salt are really like (atoms, forces, spatial configurations, etc.), are completely within the Objective Model. Your belief about directions to the nearby convenience store, told to you by someone before you went, and found to be correct when you went, are now in both models. And sometimes the Subjective Model is what will help you and sometimes the Objective Model is what will help you.

And what I continue calling attention to is that both of these Models may be operative simultaneously in all of us. When we are walking carefully, we are primarily using the Subjective Model. When we are choosing a route, we are primarily using the Objective Model. When we are making love, we are primarily using the Subjective Model. When we are planning a date, we are primarily using the Objective Model. But we are probably almost always using both Models to some extent at the same time. In fact, it is essentially impossible not to be using the Subjective Model to some extent in everything that we do, moment-to-moment.

And because both Models are operative in us at the same time most of the time, it is not surprising that we have difficulty telling the Models apart, and therefore tend to try to integrate them into one, even though in certain respects they may be incompatible. And this tendency, I maintain, is part of how the "mind-body problem" arises.

Now it is time to clarify further the third entity, "Reality," (capitalized) in our model that will consist of Subjective Model, Objective Model, and Reality.

As we know, most of our words have more than one meaning, and the intended meaning in a particular act of communication or thought is often fairly evident from the context in which it is being used. But sometimes such difference in meaning is unclear, and when that is so, communication and thought become ambiguous. And that can certainly be true of the concept of "reality." When the word is being used, it can have substantially different meaning depending on whether one's thinking is primarily involving the Subjective Model or the Objective Model.

To understand two drastically different meanings of "reality," we have to go back to our discussion of solipsism and bring ourselves forward. I mentioned that, as a part of the Subjective Model, almost all of us make the assumption that we are not alone, and that there is more to "existence" than just our own immediate, ongoing subjective experience. An assumption, of course, is a belief, and a belief, as we are using it in this discussion, is a model. So that assumption is the creation of a model. So we need to look more closely at that process.

Very early in our existence, almost all of us begin to "structure" (develop beliefs about) our subjective experience, that is, produce a model of it, that includes, by virtue of "imagination," what is not presently being directly experienced. The development of the cognitive map is an example. When we play peek-a-boo with our infant, we are getting our infant used to the idea that things are still present or nearby even when we don't see them. The infant retains an image of that which has just been seen, and learns that in time it will be seen again, so the imagination provides a cognitive map that includes the unseen object still existing, in a place in that cognitive map, even though not visible currently because of interfering circumstances (e.g., Mother's hands over the infant's eyes).

And as a part of everyday experience, Mother disappears and reappears. Before long the infant "learns that" (develops a model that includes the belief that), under certain circumstances, Mother is in the next room. The infant can "see" her in the next room in his or her "mind's eye," or imagination, and it becomes a belief. Here is another example of the lack of a clear line of demarcation between subjective experience and belief about that experience. Mother is not actually seen, but Mother is imagined to be in the next room. That image also represents a belief, that it is "really so," such that the belief can result in predictions that will often turn out to be correct (e.g., crying will bring her back right away, because she's just around the corner).

(Note that images imagined are not necessarily beliefs. For instance, we can imagine things that we believe are not so. Images are beliefs only insofar as they tend, or would tend, to produce predictions in specific situations. We also have the ability to imagine that which we believe is not so, or that we are not at all sure about.)

So what we are considering here is the "belief in the existence of the unseen." We develop the "awareness" (belief) that things exist even though we don't necessarily "see" (experience) them. This is our first development of the concept (model) of "reality," or belief in the existence of things that are independent of subjective experience. The potential or actual imagination (including memory) of this set of things that exist independently of our experiencing of them indeed is much of what we are meaning by "the Subjective Model," along with any rules by which we believe these things behave such as to make them predictable.

But also note that the image of those things that exist independently of subjective experience is basically similar to the perception of those things when experienced within subjective experience. Mother in the next room is experienced very similarly to Mother in the same room (and visible). When Mother walks into the next room, she doesn't, in the mind of the infant, transform into something totally different, and even unimaginable. As noted earlier in this presentation, the only material out of which we can construct our models is subjective experience, i.e., the entities of subjective experience. So when we imagine (model) Mother as being elsewhere, our image of Mother remains basically the same as our perception of Mother when Mother is present.

So we readily include in our developing Subjective Model images of things that don't change just because we cease experiencing them. This model is that of a world that exists unchanged whether we experience those entities or not, referred to usually as "reality." Things are considered to be as they are experienced, and remain the same as they have been experienced even when we stop experiencing them. There is thus, in the Subjective Model, one "reality," sometimes experienced and sometimes not. This is the beginning of what, in the Objective Model, becomes an important inaccuracy. But within subjective experience and within the Subjective Model, there is no problem with the use of this assumption. Within the Subjective Model, the automatic assumption is made (in infancy) that the world is as subjectively experienced, whether subjectively experienced or not.

(Not all that is subjectively experienced is considered "real." We do at times produce images in our minds that we know to be creations rather than reproductions, that is, things that we imagine rather than remember or actually "see," and that we would predict that we would never "see." What is "just being imagined" may be considered "not real," "unreal," or "imaginary."

On the other hand, under some circumstances we might label as "real" the image itself, of something, even though it is an image of something that is "imaginary." The unicorn is not real, even if a particular picture of one is. So we use a potentially somewhat slippery terminology when talking about "reality" within the Subjective Model, but this slipperiness may not be a problem if we recognize the different uses of some of our words.)

So now note how different this assumption about "reality" within the Subjective Model is from our conclusions within the Objective Model regarding the "real" house and the houses in the balloons over the heads of the two people in the cartoon. In that scenario, the entity which is independent of being seen or thought about, "the real house," is entirely different from that which is "in the minds of" the two individuals "perceiving" the house (such that what they have available to each of them is only what is in the balloon over the head of each). The house in each balloon is a model of the "real house," not the "real house" itself. According to the Objective Model, there is the world of subjective experience and the world independent of it being experienced.

This "reality" that is meant within the Objective Model we can now call "Objective Reality," and contrast it with "Subjective Reality," the "reality" that is usually meant within the Subjective Model. To simplify, whenever we are referring to Objective Reality, we can simply use (the capitalized) "Reality."

Within the Objective Model, our perceptions of and thoughts about entities in Reality are considered to be just models of those entities that presumably "exist in Reality." But the assumption in the Subjective Model, developed by the infant and retained as a part of the Subjective Model throughout life, is that there is one "reality" (Subjective Reality), that is as experienced and as imagined (as previously experienced), or remembered, and therefore the same whether experienced or not.

So in the Subjective Model, "experience" and "reality" are automatically (from infancy) assumed to be made, so to speak, of the same thing, whereas in the Objective Model, "experience" is different from "Reality," in that "experience" is a model of "Reality," and made of something different from "Reality," that is, made of the entities of subjective experience. This is consistent with the idea that what is in the balloon over the head of the person seeing the house refers to something about the neurons in that person's head, whereas the "real" house is made of bricks, etc.

We can say here, however, that even a thought or a feeling may be considered to be a model (perception) of a process occurring in Reality, that is, in the brain-in-Reality, whatever that is. If, for instance, it turned out to be true that a particular feeling would occur in an individual if and only if a particular neuron, or a set of particular neurons, in that individual's brain were firing, then one could refer to that feeling as the "perception" of the firing of that or those neuron(s) "in reality," and thus a model of it (the intensity of the feeling perhaps being, e.g., a model of the frequency of firing of the neuron or of the number of such neurons firing).

Notice that if we take this approach, then the perception of the house (within subjective experience) is really a perception of the network of neuronal interactions in the brain, that is in turn a model of the house. So we would be saying that subjective experience is a model of the neuronal activity of the brain, which, in turn, is (or at least can be) a model of the entity (e.g., house) in Reality (what exists independently of our perceiving it or thinking about it).

And indeed this makes sense because we know that entities can be experienced that do not actually exist "in Reality," as when we have hallucinations and dreams. In such cases, the neuronal activity that is a model of the hallucinated or dreamed house is taking place in the absence of the house existing "in reality." The perception or image of the house is a model of the neuronal situation, but it may or may not be a model of the house in Reality.

(We are also making an assumption here that reports of any kind of subjective experience by an individual could be demonstrated to be "correlated" with some finding(s) in our growing set of neurological imaging techniques and/or other neurophysiological techniques. We do not know this, of course, but our growing set of findings gives no indication that there are such reported or reportable subjective experiences that are not "correlated" with neuronal processes, and we would always be able to say that we just had not so far found a way to do so if there were some reports of subjective experience for which we had not yet found a neurophysiological "correlate." All evidence to date seems to indicate that the central nervous system, functioning adequately, is necessary for subjective experience to occur. So I will be making that assumption for the present.)

In the Subjective Model, things are as they seem; in the Objective Model, there are (1) things, and then there are (2) our perception (and memory and imagination) of those things, that is, our ways of experiencing (modeling) those things.

When I look at a chair, then I will say to myself that the chair is "real," not "imagined," and thus a part of my Subjective Reality. However, when you and I are discussing our perception of the chair, I will say that your perception of the chair and my perception of the chair are two different models of a third thing, namely, the chair that exists in Objective Reality.

Within the Subjective Model, you will primarily use the word "real" to distinguish between (1) what you perceive, or could perceive, within your subjective experience and (2) something that you have imagined (or even dreamed), or could imagine, that you believe would be impossible for you to perceive because of it not "existing" (as opposed to an inability to perceive due to some limitation in your own ability to perceive things or to get into the proper position to perceive such things). So within your Subjective Model, when you are looking at something, or hearing or feeling something, what you are seeing, hearing, feeling, etc. is what is "real," as opposed to "imaginary." If you are traveling down a curving road, what you see you would classify as "real," just as you would classify the image in your mind of what is about to be perceived as you go around the curve. And you could imagine something around the corner that you knew was not there even though you can imagine it, something "unreal" or "imaginary." In the Subjective Model, "reality" (Subjective Reality) is as perceived or as could be perceived, being therefore made of the entities of subjective experience, as has been noted.

But, again as we have noted, within the Objective Model, "Reality" is by definition a totally unknowable world that our subjective experience and our (Subjective Model and Objective Model) beliefs are models of. In the Objective Model, the only "access" to Reality is our modeling of it, using the entities of subjective experience as the material with which to do that modeling, and with the recognition that it is entirely possible, and even likely (considering what science has come up with so far) that there is nothing within subjective experience that can be used to create a completely satisfactory model of Reality, beyond mathematical equations modeling the results of measurements.

So we can actually become clearer in our thought and communication by considering that "reality," as the word is customarily used, could mean either "Subjective Reality" or "Objective Reality," depending on whether the term is being used within the Subjective Model or the Objective Model. In this presentation, when the term "Reality" is being used, it is always referring to "Objective Reality" as the term has just been used, especially since this whole presentation, of course, is an act of modeling within the Objective Model.

So we can summarize our developing model by once again clarifying that there is the Subjective Model (including subjective experience itself), the Objective Model, and Reality, which both the Subjective Model and the Objective Model are considered to be models of. And the presumed "existence" (by definition only) of that Reality is the reason that those Models can actually work (allow for any kind of reliable, successful prediction).

A metaphor that somewhat depicts what is being said is as follows. There is a contest going on, with people trying to win a prize for guessing at what is behind a curtain. But they are not guessing at what it actually is; they are guessing at what it is like. So they make their guesses as to what it is like, and the contestant leader responds with answers that indicate how good the guess is. The contestant leader only responds with "good" or "not so good" ("good" meaning will result in increased likelihood of success of prediction and ability to do things, and "not so good" meaning will result in increased likelihood of being surprised and of making mistakes), and the contestants never get to see what is behind the curtain. But if we can mostly get "good" responses, that is what we want, and we aim for the time when we only get "good" responses for the rest of time (though we will never be sure we have gotten there). That is the best we can ever do. (In a sense, perhaps, this contest is the living of our lives.)