Lesson 9: the Development and Testing of Theories

Chapter 5

Lesson 9: The Development and Testing of Theories

The following story was told by a relative of a young man who was killed in an automobile accident:

A few months after his death, a grandfather clock owned by the mother of the man--a clock that hadn't worked in years--began to tick during the early-morning hours of Mother's Day. It continued to tick for the rest of that day until the early evening. The man's relatives wondered why this apparently broken clock would begin ticking on this specific day. They explained the event by concluding that the young man had come back from beyond the grave to wish his mother a Happy Mother's Day. What was their evidence? There were three observations of most importance to them: the clock had not worked in many years; it began to tick at about the time that the man had been born; it stopped ticking at about the time of his death. To the relatives, the best explanation for these observations, when looked at as a whole, was that the man's spirit had caused the clock to start working for a number of hours on that Mother's Day.

This story illustrates a strong tendency of humans: we seem to have a strong desire to explain events in the world around us, especially mysterious events such as the one described in the story. In other words, we often are engaged in constructing and testing "theories."

As was mentioned in Lesson 3, a theory, most simply defined, is a tentative explanation of a phenomenon. That is, a theory is made up of at least one claim that is used in an attempt to explain a phenomenon. For example, in the story above, the explanation given by the relatives for the ticking of the clock involved the following claim: the disembodied spirit of the dead man started and stopped the clock at specific times. In general, we state that we have "explained" something when we are able to describe the cause or causes of that thing. Thus, a theory explains a phenomenon in terms of its causes, such as what caused the development of a mental disorder, why there are more murders in the United States than in many other western countries, what causes the movement of the planets, or why someone is doing so poorly in school.

The story about the ticking clock illustrates three problems that tend to be shared by theories we develop in our everyday lives: (a) everyday theories often ignore the complex nature of causation (recall the discussion of multifactorial causation in Lesson 3); (b) everyday theories often are based on questionable assumptions; and (c) everyday theories rarely are subjected to further testing (that is, verification or falsification). First, the theory of the ticking clock provides a very simple explanation that ignores the complexity of most events in the world: the clock was said to have started because of the actions of a disembodied entity rather than, say, because of an unusual and complex combination of changes in temperature, humidity, and barometric pressure. The theory also is based primarily on a questionable assumption: that supernatural entities (if they exist at all) are able to affect events in the natural world. And, finally, the theory was not tested further to see if it was likely to be true: it was developed only to explain a particularly unusual event, and only after the fact. The theories of science, on the other hand, are typically complex, often are based on careful reasoning, and generally are subjected to a great deal of testing to see if they are likely to be true. In the next section, we will discuss the way in which theories typically are tested.

We Test Theories by Deriving Predictions

In previous lessons, we have talked about the need to make observations in order to test claims. But what observations should we make when testing a particular claim? In testing a claim, we first need to make predictions about what we should find if the claim actually is true. We then need to make the relevant observations. The results of this process will provide evidence either for or against the claim. For example, some people believe that babies are more likely to be born during full moons than at other times of the lunar cycle. It is a simple matter to derive a prediction that will test this claim: if the claim is true, then we should observe more babies being born at a full moon than at any other time. A study that looked at 70 million births over about two decades found no evidence that babies are more likely to be born during full moons (see Pyne, 2002, for a report on this study).

Because theories are made up of claims about the cause or causes of a phenomenon, we test theories in the same way that we test any other kind of claim. Thus, in order to test a theory, we need to do two things: (a) make a prediction about what should be observed if the theory is true, and (b) make the relevant observations. To illustrate this, let's take the example of "self-complexity." Self-complexity may be defined as the degree to which the self-concept (the set of beliefs about one's personal qualities and typical behavior) is made up of elaborately interrelated or interconnected parts. The following theory was developed by Patricia Linville: low self-complexity causes people to be more affected emotionally by life events than is the case with high self-complexity. The following prediction was derived from this theory: if people are told either that they have succeeded or that they have failed on a task, people low in self-complexity will show a greater change in mood than people high in self-complexity. This prediction was verified when relevant observations were made. We would not want to state that the theory is true based on this one result; but it is consistent with what we should observe if the theory actually is true.

Are Theories Merely Someone's Opinion?

Based on this discussion, you should be able to see that the everyday meaning of the term, "theory"--that is, that a theory is "just an opinion" and, therefore, that one theory is as good as any other--is not the meaning used by scientists. Instead, a scientific theory represents an explanation that has been verified to some extent by observations made to test predictions derived from the theory. The greater the number of studies that seem to verify the theory, the more confidence we have that the theory is an accurate representation of reality. For example, the theory that states that related species, such as chimpanzees and humans, resemble each other physically and behaviorally because they have evolved from a common ancestral species has been verified by a very large number of predicted observations. Thus, we can have a great deal of confidence that this particular evolutionary theory reflects reality. In fact, it has been so well confirmed that most biologists consider it to be a "true theory."

Even a well confirmed theory, however, is not a completely accurate representation of reality. When developing a theory, we are not attempting to explain a phenomenon in all of its mind-numbing complexity. Instead, we are trying to focus on what we consider to be the most important aspects of the phenomenon; and, in doing this, we typically are concerned with solving a particular problem related to the phenomenon. You may be able to understand this better by thinking of a theory as if it were a map. No map of a geographic region attempts to describe that area in every detail. Instead, the map focuses on particular aspects of the region--aspects that are selected with a particular purpose in mind (that is, a particular problem to solve). For example, a "relief map" focuses on describing in detail variations in the elevation of a region, whereas a "road map" focuses on describing in detail all of the primary and secondary roads in a region. You would not use a relief map to drive from Chicago, Illinois, to Bettendorf, Iowa, just as you would not use a road map to determine the height of particular hill outside of Bettendorf.

A theory is analogous to a map in that a theory also focuses on selected aspects of a phenomenon and describes them only in the detail necessary for achieving a particular goal. For example, the theory about self-complexity described above is not trying to explain every possible reason why emotions vary from one moment to the next; and it is not even trying to describe every possible aspect of self-complexity that may be important for its effects on mood. Instead, theorists begin with a particular problem that they would like to solve and then develop a theory that focuses only on those aspects of the problem that they believe will be important for its solution. The results of their observations will tell them whether or not their theory is good enough for the goal they are trying to achieve.

Critical Thinking Questions

Question 9-1
For each of the following theories, derive a testable prediction:

The car won't work because the starter is broken.
People raise their self-esteem by comparing themselves to others who are worse off than they are.
The television won't turn on probably because it isn't receiving any electricity.
Schizophrenia is caused by increases in the activity of a brain chemical called dopamine.
Women are more attracted to men who appear to be wealthy than men who do not appear to be wealthy.
Culture is an important influence on people's self-concepts.