How Does Piaget View the Learning of physics?（2）

The previous article discussed the innate psychological intuitions that children possess for learning physics. The discussion that follows seeks to answer a further question: what is the epistemological distinctiveness of physics as opposed to other forms of knowledge? Piaget holds that "physics" refers to a science that "reads off" reality. For example, suppose I am sitting in a library and want to understand why a lamp can illuminate the entire space. I need to know that the concept of "electric current" exists, yet I have never seen an electric current. Likewise, to understand why we can drink a beverage through a straw, we need to know that "atmospheric pressure" exists, yet it is difficult for us to observe atmospheric pressure directly. It can thus be seen that only on the basis of physical concepts and theories can we understand (or "read off") the principles beneath the appearances of the material world; it is difficult for us to observe "reality" directly.

When we seek to understand the material world, what we are essentially doing is finding causal relationships between phenomena; for instance, the lamp lights up because the power supply has been connected. In the history of science and philosophy, however, people have often equated "regularity" with "causation." For example, when one event occurs and another follows, this has long been observed by people as a kind of "regularity," and so people assume by default that the occurrence of the former event caused the occurrence of the latter, that is, that a causal relationship exists between the two, yet they are unable to state clearly what this causal relationship specifically is. Accordingly, the philosopher Hume held that there is no necessarily connected "causation" in the world, and that all such connections are no more than a subjective habit of thought in the human mind.

Faced with this epistemological predicament, Piaget argues that the developmental direction and the higher form of human cognition naturally point toward "formal thinking," that is, the transition from the "concrete operational stage" to the "formal operational stage." This mode of cognition tacitly accords with the process of exploration in the physical sciences: at first, people can observe only concrete physical phenomena, but once the human brain has developed to the "formal operational stage," it inevitably brings this "logico-mathematical framework" to bear in "reading off" the world. When we use this rigorous framework to "translate" chaotic sensory information, we "construct" physical facts. These facts are the scientific facts that we jointly establish and that we are currently able to recognize. Therefore, when confronted with the same phenomena, we can directly apply this physical knowledge to understand and solve practical problems. Piaget's central claim is thus that the exploration and development of physics as a science conforms to the laws governing the development of human cognitive ability: that is, the understanding of the world moves from "concrete experience" toward "formal operations" founded on a "logico-mathematical framework."

Piaget further explains why the "logico-mathematical framework" in the human mind can serve as the scaffolding of "formal operations" upon which the edifice of physics is built. When physicists investigate some physical law on the basis of some physical phenomenon, they often seek inspiration among various purely mathematical and logical frameworks, until they find a suitable mathematical structure, which they apply to "reading off" reality, thereby constructing some "physical model." For example, Maxwell used a set of partial differential equations (a mathematical structure) to build the model of the electromagnetic field, and Schrödinger used the wave function (a mathematical structure) to build the quantum model. Piaget therefore holds that the essence of our exploration of the causal relationships behind physical phenomena is to "implant" a particular mathematical-logical structure into a particular objective reality, so that the particular laws in the real world become the "necessary results" of the operation of that mathematical structure. It is precisely by constructing "models" in this way that human beings have achieved the fullest possible understanding of the deep mechanisms of the material world.

The history of science also shows that the development of physics has always lagged behind the development of mathematics. This is because the development of physics must wait until the human brain has matured in mathematical and logical frameworks (formal operations) before mathematical tools can be "applied" to the real world in order to "read off" and construct physical facts. Physics is by no means the simple picture of reality that empiricism portrays. Empiricism is like humanity still being at the stage of "egocentrism" in its history, just like the infant's initial mode of cognition. The historical footprints of humanity's exploration of physics are isomorphic with the developmental process of individual cognitive ability. Therefore, understanding how physics as a discipline came into being from nothing helps us understand how children make the transition from concrete sensory experience to the learning of abstract physical knowledge.

‍ ‍Surveying Piaget's discussions of "how human beings carry out mathematical and physical inquiry," whether from the historical dimension of human civilization or from the dimension of individual learning from childhood to adulthood, we can see that if we wish to understand "how the ultimate truth of the universe comes to be known," we must acknowledge that human beings can never step outside their own physiological structure and logical framework in order to know the world. This is why "physical reality can only be the way it presents itself to us": the universe we see is necessarily constrained by our cognitive structure. From the standpoint of the object, the subject could not have been otherwise. It is no accident that the universe has evolved living beings possessing this cognitive structure; the reason human beings possess such logical and mathematical capacities is that the objective laws of the universe's evolution must, after a very long time, give rise to beings capable of understanding it. Piaget's epistemology therefore ultimately leads to a conception of truth based on "subject-object isomorphism": when human cognitive logic coincides with the operating rules of the universe, we touch a transient or partial truth. Of course, we can never reach absolute truth.

"Causal attributions enable us to 'understand' physical reality by reason of this convergence between what the objective operators do physically and what the subject is able to effect in his deductive reasoning."