We can achieve some expectations and some sense of causal relationships through observation and induction—the drawing of inferences from a series of individual observations. For example, there has been extensive use of surveys or experimental collections of data in connection with medical science and the study of health issues. These studies are classic opportunities for inductive and probabilistic reasoning. We find a significant statistical correlation between certain environmental or behavioral characteristics and certain health characteristics in a population. That statistical correlation suggests that there may be a more substantive relationship. And, it may or may not, in fact, be a causal relationship. However, to address that underlying question of causality, one generally needs to develop an explanatory theory as to how and why the two phenomena relate to one another.
Albert Einstein reportedly remarked that “The most incomprehensible thing about the physical world is that it is comprehensible.” Quoted by, inter alia, Lord Rees, From Here to Infinity, p.80; Stephen Hawking and Leonard Mlodinow, The Grand Design (2010), p.87. Comprehensibility depends first upon the existence of certain regularities in the physical world that allow us to generalize. If knowledge of the physical world required specific or unique information about each atom or constituent piece of the world, then the magnitude of the data required would clearly exceed the capacity of the human brain, and we could never know the world. See Carl Sagan, Broca’s Brain, p.16. However, it just so happens that there are substantial uniformities, regularities and patterns, so that much of the physical world can be accurately described in a relatively small amount of information.
Some of the more interesting of these regularities are often referred to as “laws of nature.” We shall talk more about that concept later. But, I think that something more subtle and intriguing is encompassed in Einstein’s reference to comprehensibility. In part, his comment undoubtedly reflected the surprising ability of mathematics to be used to predict physical events, which I discuss below. In part, the comment also likely captured this other concept of insight or understanding—not just that we have tools that predict accurately, but that we have explanatory theories that seem to make the relationships make sense, i.e., be comprehensible.
It is not clear that there is any reason why the ability of the human mind to “understand” physical phenomena would necessarily have any direct correlation with the actual physical relationships that exist, except that the species would probably not have survived if the mental constructs (or models) of which we were capable veered too dramatically away from the actual environmental facts. At the same time, by such reasoning, that apparent conformity need only extend to matters relevant to our existence, specifically to our survival and reproduction. It may be that human cognition is capable of no more than relatively superficial comprehension of our Universe, so that the deeper truths (those not directly related to our survival, at least not yet) are simply beyond our ability to comprehend. We shall encounter that possibility from time to time below.
The concept of causality
It appears that man’s concept of comprehensibility depends fundamentally upon a belief in the existence and pervasiveness of causality or causal relationships.1 There are some interesting questions about what we mean by “causality.” At a minimum, as we humans understand it, if one event is a cause of another, then the causal event must have preceded the caused event in time. A subsequent event cannot be a cause. Someday, of course, we may discover that temporal relationships are more ambiguous or fluid; but, for now, chronology plays a central role in our understanding of reality. Next, we would expect that the caused event, under the existing circumstances, would not have occurred “but for” the causing event, that is, if the causing event had not occurred, then the caused event would not have occurred either. (This concept of causation is related to the “falsifiability theories of causation.”) In addition, one might say that A causes B if, all else equal, the occurrence of A will (or probably will/or in a certain percentage of the time will) be followed by the occurrence of B. The “existing circumstances”, or “all else equal”, qualification is important.
This last qualification is sometimes referred to as the “ceteris paribus” condition. It has a rather particular meaning. The “nothing else” that cannot change does not really mean nothing else, which could never be satisfied, but only nothing else relevant to the causal relationship under examination. But, even so, that qualification can still be surprisingly limiting. In certain relationships, the other relevant factors may be quite well-defined, few in number and largely controllable. For example, a hot surface burns a finger, assuming that the finger is more or less at room temperature just before the contact and that the contact is complete enough and long enough. But, in other cases, the other relevant factors may be numerous and not well-understood or, even if understood, not readily controlled for or measured. We shall see later some of the issues that such circumstances present.
But, let’s step back for a moment. From where do we derive the sense or awareness of causality? Perhaps, the belief in causality is an empirical derivation, that is, we observe correlations and conclude, from the empirical experience, that there is causation. However, Hadley Arkes, a professor of political science, argues that “[t]he notion of causation must be in us, so to speak, as a precondition of experience; it is one of those understandings, built into our natures, which makes it possible for us to ‘have experiences.’” First Things: An Inquiry into the First Principles of Morals and Justice (1986), p.67.
A priori knowledge
Arkes attributes this conception of causation to Immanuel Kant and Kant’s argument that there are necessary, or a priori, truths that exist independent of experience. He paraphrases and quotes Kant to the effect that “the nature of the rule becomes more evident to us as we see it manifested in any experience… But unless we understand already the immanent necessity of a rule—unless we presuppose that events are indeed arranged in a temporal order, with certain events A preceding certain events B and determining the position of B in the sequence—unless this elementary point is absorbed as a necessary truth, it becomes impossible to impute any meaning to the succession of perceptions that flash before us. As Kant remarked, ‘it is under this supposition only…that an experience of anything that happens becomes possible.’ … [T]he awareness of the rule—the awareness of the very notion of causation—‘was nevertheless the foundation of all experience, and consequently preceded it a priori.’” Id., p.64, quoting from Kant’s Critique of Pure Reason.2 In short, humans have built-in an understanding or, perhaps, an assumption of causality that leads us to look for and enables us to see causal relationships. In fact, it would be asserted, if we did not have an inherent understanding of causality, we would be unable to detect it.
There are other examples of innate or inherent mental constructions or structures, and the same caveats would appear to apply. As an example, the conception of space and time would seem to precede a priori actual experience. Indeed, one could argue that we could not understand our physical experiences without such concepts being given in advance of and as a basis for perceiving those experiences. See Arkes, First Things, pp.56–57.3
Similarly, experiments have demonstrated that our visual perception is based upon certain innate perceptions. For example, the laws of perspective, which were only gradually discovered by Renaissance artists, appear to be embedded in our minds. The point is demonstrated by the adjacent images of the Leaning Tower of Pisa which the mind persistently perceives as diverging, with one tower appearing to lean noticeably more even though the two are identical. The reason is that the mind “knows” that two neighboring towers will appear to lean toward each other as they rise from the ground in a single scene (the law of perspective), so if the towers do not in the photo lean toward each other as they rise, the mind concludes—and the eyes see—that one tower tilts more than the other. Stephen L. Macknik and Susana Martinez-Conde, Sleights of Mind: What the Neuroscience of Magic Reveals About Our Everyday Deceptions (2010), as reported in The Wall Street Journal, November 20–21, 2010, p.C12.
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