Excerpts from Philosophical Concepts in Physics (1998)



Excerpts from Philosophical Concepts in Physics (1998)

by James T. Cushing

A current popular conception of science, that bears some similarity to the type of program proposed by Francis Bacon, can be set down in outline form as:

A observation

B hypothesis

C prediction

D confirmation

This simple model of science and how it operates depicts the process as a purely objective one in which careful observations are made, or controlled experiments performed, after which rules or laws are extracted from these empirical data and general hypotheses are formed. Next, these general hypotheses or conjectured theories are employed to predict new observational consequences. These predictions are used to confront reality and, if the predictions are verified, then the theory has been confirmed. By this process science amasses more and more knowledge about the physical world and brings us closer to the truth.

Let us now examine this model a bit more critically. Certainly nearly all physical scientists have agreed that one must begin with the data of sense experience. Not only men like Bacon, Galileo and Newton were of this persuasion. Harvey, in his revolutionary and pioneering treatise on the circulation of the blood in the human body, urged, as Aristotle had, that we proceed from things more known to those less known. This approach is elegantly and concisely summarized in his statement ‘that the facts cognizable by the senses wait upon no opinions, and that the works of nature bow to no antiquity . . .’ But what are we to do with these facts and data?

Previously we termed induction the process of abstracting general laws or principles from specific observations. Can one ever know with certainty that a law gained from induction is correct? David Hume, the eighteenth-century British [Scottish] philosopher, historian, economist and essayist, held that philosophy is basically an inductive, experimental science of human nature. In his An Enquiry Concerning Human Understanding (1758), he discusses the notion of causality, the validity of induction and the necessity of sense data preceding ideas . . . In analyzing the concepts of cause and effect, Hume points out that what we actually observe is only one event following another, rather than a necessary connection between them. There is no direct observation of a cause (or connection) for the supposed effect. Since what we see are events conjoined (or associated) but never connected, the terms cause and effect are words without operational meaning. If we know just one instance of two events being conjoined (one following another), then we do not state a general law governing their connection in terms of cause and effect. However, if we repeatedly see the same pair of events conjoined, as a body initially at rest being struck by another moving object so that after the collision the first body is also in motion, we do refer to cause and effect . . . That is, from the occurrence of constant conjunction, we infer a necessary connection. However, the difference between one such pair of events and many is that the mind is carried by habit to feel the existence of a necessary connection (in our thought).

In essence, Hume asked what reason we have to suppose that future observations would resemble past ones. He challenged placing unlimited trust in universal, predictive laws induced from observed facts. As a simple example, from the fact that the sun has risen every day in the past since the beginning of recorded history, we might induce the ‘law’ that the sun necessarily rises every day without exception. Can we, however, be absolutely certain that the sun will rise tomorrow? No. There is no way around the provisional character of physical laws gained by induction. Hume saw the need for induction, but felt its validity to be unprovable.

The later British philosopher, economist and ethical theorist John [Stuart] Mill also wrote extensively on the question of induction. Mill was a child prodigy educated by his father so that he read Greek by age eight, when he started Latin, studied Euclid and then Aristotle at age twelve. He was not only a philosopher, but a political activist as well. In his System of Logic (1843), Mill discusses induction and the assumed uniformity of the laws of nature. He argues that the main problem for the science of logic is a justification of the process of induction that is the operation of discovering and proving general propositions. Mill sees the question to be one of discovering the conditions under which an induction is logically legitimate. Involved in all inductions is the assumption that the course of nature is uniform or that the universe is governed by general laws. However, this is itself an example of induction since we assume it to be true because it has always turned out to be so in individual instances. This uniformity of the course of nature is the premise (or first principle) that can be used to justify induction. Unfortunately, neither Mill nor anyone else has proven the correctness of this premise. It remains an assumption, albeit one that few dispute and without which we cannot do science.

You may feel that a concern for the nature of the cause-effect relationship, the validity of induction and the status of physical laws is just philosophical nit-picking that is best left for some idle Saturday afternoon and that we can get on with the serious business of science without being concerned about such questions. But even if we gloss over these issues, consider the relation between observation and hypothesis. How independent are the operations of gathering data and of discovering theories? The fact-gathering necessary for science is rarely random. As Charles Darwin . . . pointed out, no one can be a good observer unless he is an active theorizer. That is, the discovery of new facts and the evolution of a theory are reciprocal processes. The experiments a scientist undertakes do not yield immediate and obvious sense data but rather those collected with considerable difficulty. She must have a theory to guide her in this search, else she would not know which of the myriad phenomena in nature to examine. . . [30-32]

1) What are the author’s main points in these brief excerpts?

2) Does the author’s argument agree or disagree with your understanding of how science works? Explain.

3) Evaluate the following statement: “Scientists simply collect facts from nature and then arrive at better and better theories based upon their observations.”

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