A prediction is simply a description of a future state of a system. When a set of predictions comes true, it tends to confirm the model from which it was developed.
A system is simply any set of interacting elements. When one element influences another element, the former is said to exert a force on the latter. A dynamic system is one that changes over time. It evolves. Two things are necessary for a system to evolve. First, there must be variation within the attributes of the elements. Second, there must be forces that select for the survival of certain elements over others. That is, an element that survives must possess some attribute that was lacking in those that did not. In every evolutionary system, there must be a set of criteria, of selection pressures, of discriminatory forces that favor certain characteristics over others. In the biological world, the criterion is adaptive fitness. Somehow, the trait has got to help the organism to perpetuate its own genes. This usually takes the form of leaving more offspring. Traits that may contribute to this are speed, stealth, intelligence, litter size, various physical adaptations, and so forth.
Some elements are so successful that they grow large and ultimately branch into daughter elements. In biology, this is called adaptive radiation.
A species within a habitat is just one example of an evolutionary dynamic system. Some other examples are belief systems (including any branch of science), computer programs, graphic illustrations, rules for successful social interaction, electronic cellular automata, and the object of our interest, the human community.
The human community is a dynamic system, subject to evolution over time. The forces at work here at not just random genetic mutation and natural selection, but also, to an even greater extent, human artifacts (including social structures and belief systems) and human selection (conscious and unconscious) from among those artifacts.
The criteria used by humans to select which artifacts will survive and which will not are many and varied. And the power that each individual has to perpetuate or diminish a given artifact varies with the individual. The primary criterion is “does or will this artifact make me feel better?” The importance of emotions to humans cannot be overstressed, because that is the only thing that motivates them to behave, and behavior is essential to preserving the dynamism of the system.
A state is simply a description of a dynamic system at some specific moment. A state is said to be deterministic if it can be deduced from an examination of the forces acting on the system over time. This is true of every system and thus, every state is deterministic in theory. Whether or not it is deterministic in practice is another matter. Some systems exhibit a high degree of randomness and complexity, which can be modeled only to a certain level of detail and specificity and no further.
Since it is a dynamic system, the human community must also be deterministic. Thus, there can be only one future state for any given time and place. The fact that human forethought may be applied and behaviors altered as a result does not indicate a violation of the deterministic nature of the system. It simply means that human forethought is another force acting on the it.
One way to find out what the state of a system will be at some future point in time is to construct a model of it, and run the model at faster-than-real time. A model is simply another system that resembles the original system in certain essential aspects. No model is ever a perfect representation of the original system. Otherwise, it would not be a model; it would simply be an identical copy of the system.
The more complex the system, the more difficult it is to model accurately. There are many factors influencing degree of complexity. Among these are: number of elements, degree of interconnectedness of elements, number of ways in which elements may affect each other, whether or not any of the elements are capable of forming superstructural elements, and the number and kind of superstructural elements.
The human community is the most complex system known by this author at this writing. It is composed of billions of elements, there is a high degree of interconnectedness of elements, a large percentage of the elements may affect other elements in more than one way, and there are superstructural elements, at several levels of scale. How then, can anyone hope to construct and run an accurate model of a system of such surpassing complexity?
The answer is manifold. To begin with, there is clearly a limit to the degree of detail with which the system may be modeled. But there are several factors that make the system much simpler than one might first assume. For one thing, we don’t have to model the behavior of every quark in every atom in every molecule in every protein in every cell in every tissue of every organ of every human being. This is a good thing, because it would have been impossible to do. The fact that the quarks of this system are neatly arranged into multicellular organisms means that the system is already highly ordered. And the higher the degree of order within a system, the easier it is to model.
Retrodiction
There is a particular class of prediction that merits special attention. It is called retrodiction. A retrodiction is simply a prediction of the future discovery of evidence of past events. Like all predictions, when a retrodictive prediction comes true, the accuracy of the model tends to be confirmed. For example, an anthropologist might predict the discovery of fossil bones of a primate that possessed characteristics of both apes and humans. If such a discovery were made, it would tend to confirm the anthropologist’s model. Retrodiction can also be applied to history, to confirm a model of human behavior. Let’s say your model states that during times of extreme social stress, belief in the supernatural tends to increase. Working from this model, you predict that during the time that bubonic plague was devastating Europe, supernatural beliefs and activities were higher than periods before or after. If research shows this to be true, the discovery tends to confirm your model.
One factor that is often omitted from models of human behavior is the effect that predictions themselves have on that behavior. This is the mechanism of the self-fulfilling prophecy, which is one of a family of self-affecting prophecies. The effect of a prophecy seems to depend heavily on the degree of control that the people affected by it believe they have over it. If an unpleasant event is predicted, and those affected believe they can do nothing to prevent it, their very inaction may make the event more likely. Such was the case when the Aztecs were destroyed by the Spanish conquistadors. Their fatalistic belief that their destruction was inevitable probably contributed heavily to its actual occurrence.
On the other hand, if those affected believe that they have some control over events, their response to an unpleasant prediction might be precisely the opposite. They might work hard to prevent it, making the prediction a self-preventing prophecy. Dystopias such as those described in Orwell’s 1984 and Huxley’s Brave New World fall into this category, and have made themselves less likely to occur as a result. The general principle that can be drawn is this: Public knowledge of potential future events tends to alter the probability of their occurring, either increasing or decreasing it. What would have been perfectly valid predictions are made invalid by the actions of individuals acting on information presented in those predictions. This is one reason why pessimistic predictions have such a poor record for coming true. The very conditions they describe tend to make people work to avoid them.