Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
And so the Israeli physicist David Deutsch counters that we used to live in a world of supernatural entities. Then we discovered that we are capable of explaining how the world works because the world obeys mathematical laws that our brain can master. Therefore we became universal beings, capable of understanding anything that happens in the universe ruled by those laws of nature. A higher intelligence (incomprehensible to us) can only exist if the universe is not explicable, i.e. if there exist supernatural beings. In other words, the cognitive closure of human brains would imply that the ancient superstitions were correct.
It is the scientific "explanation" that allows us to create a long chain of interpretation that allows us to understand phenomena that are very far from our everyday experience. For example, astronomical observation consists of, in practice, just looking into devices built out of humble materials found here on Earth but, ultimately, allows the mind to visit distant worlds. The mind can "leave" the body for this spectacular voyage because of the "explanations" that guarantee it is not just being tricked by drugs. There is something special about this process that makes humans truly unique.
Deutsch disagrees with those who think that there is nothing special with this typical planet of a typical star of a typical galaxy (the principle of mediocrity): humans have created conditions (for example, low-temperature refrigerators) that are very rare in the universe. Deutsch emphasizes that most of the universe is very different from the environment that humans created in their cities, homes and especially laboratories. What made humans unique is that they can use technology to expand the capabilities of their brains. Whatever caused their brains to evolve the way they did, those brains are now capable of going beyond their original survival functions. And the reason that technology does that is the explanatory knowledge that only humans have learned to master. What is unique about explanatory knowledge is obvious if one considers that humans managed to survive in an extremely hostile biosphere and even moved to environments that are not the ones in which they were shaped by natural selection. Other species have knowledge too, but the kind of straightforward knowledge that limits their reach to their habitat. The explanatory knowledge of humans allows them to do things that their brains were not programmed for and their bodies could not do without help from technology.
Thus Deutsch calls humans "universal constructors": humans can transform anything into anything as long as they understand the natural laws that govern the universe and then build technology according to those laws. If the universe is governed by deterministic rules, then the human brain can eventually (explanation after explanation) get to understand everything. We are capable of everything, and in particular of understanding everything. There is nothing that obeys the laws of nature that we cannot understand. If such a thing existed, it would have to be "supernatural" by definition: not obeying the laws of nature. In a universe governed by mathematical laws, the reach of explanatory knowledge is infinite, and therefore so is the reach of a brain that is capable of acquiring explanatory knowledge recursively (one explanation leading to another one). There is no limit to human knowledge. There is no limit to human creation.
Historically, it wasn't always this way. At some point humans became what their brain made possible: universal constructors. He links this conceptual revolution with the Enlightenment, that spawned rebellion against authority in many fields, including science: those rebels looked for explanations, not just dogmas. Furthermore, the Enlightenment introduced the notion that progress is good and should be a universal ideal to achieve by society. So the chain of explanations that leads to more and more knowledge became not only possible but an explicit goal of humankind.
The effect of brains like ours (brains that can deal with explanatory knowledge and therefore become universal constructors who can alter their environment at will) is significant. Deutsch points out that astrophysics is incomplete without a theory of people because people can alter the course of events that the laws of nature alone would cause. If we don't consider the actions of people, we can't understand why the Earth is the way it is.
Furthermore, the effect of a knowledge-processing brain is profound also because an intelligent deliberate transformation is actually more likely to happen than a spontaneous one: the chances that an object is changed by a spontaneous transformation (one caused only by the laws of nature) are relatively low in the grand scheme of things, whereas the chances that an object is changed by an intelligent being for whatever purpose are very high.
In other words: the universality of the laws of nature coupled with a universal constructor like the human mind yields unlimited knowledge growth.
Deutsch argues that the well-known limitations on mathematics and computations (Godel's Theorem and the likes) do not affect his claims that humans can extend knowledge indefinitely: one can understand a mathematical statement without proving it. Basically, the proof is a technicality. If you can't prove it, it doesn't mean you don't "know" something. The only limit to human knowledge that Deutsch sees is the impossibility to predict future knowledge: the fact that we can find solutions to any problem does not mean that we already know those solutions.
The physics of knowledge representation is that the physical system of the brain somehow contains a model of the physical system of the entire universe. As more and more knowledge is acquired that model becomes a better and better approximation of the universe (and viceversa). The world is knowledge-friendly because it obeys the laws of nature. The human brain is knowledge-capable. Starting with the Enlightenment, the human brain decided to exploit this capability. The spirit of the Enlightenment provided the motivation that was missing. Knowledge allows the brain to build technology to help acquire more knowledge even about facts that the brain cannot experience directly. This chain reaction leads to an endless creation of knowledge.
Deutsch's argument that, assuming the universe is run by deterministic regular "laws of nature", a mind that can understand those laws of nature can in principle understand everything, is persuasive. However, he doesn't talk about the one feature of this universe that no science has been able to express, describe and predict with mathematical laws: human consciousness; which also happens to be the one that i'm sure about, and the one i care most about. Colin McGinn has argued convincingly that the human mind just might not be capable of understanding it, no matter what. Deutsch provides a general framework in which the human mind can understand everything that can be expressed in mathematical laws, but the doubt remains that some things will never be expressed in a formal, mathematical form.
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