Scientific Thinking

Scientific Thinking: How many Scientific Methods are there?

Over the course of human history, people have developed many interconnected and validated ideas about the physical, biological, and social worlds. These ideas have enabled successive generations of achieve an increasingly comprehensive and reliable understanding of the human species and its environment. The means used to develop these ideas are particular ways of observing, thinking, experimenting, and validating. These ways represent a fundamental aspect of the nature of science and reflect how science tends to differ from other modes of knowing.   — Science for All Americans 1)

My first image of scientific thinking, the scientific method, is the one I learned in seventh grade: Observation, Hypothesis, Experiment, Collect Data, Conclusion.  The assumption was that there was one scientific method that had to be followed precisely. As I got older, I began to notice that experiments we did in class and those we read about, didn’t all follow this method. There were many versions of “The” Scientific Method.

Slowly, over the years, I realized that different methods are used for different purposes. But even then, the imagination and creative ideas of the researcher were always important.

Science for All Americans was published in 1990 by the American Association of the Advancement of Science to outline “what all students should know and be able to do by the time they leave high school.” (inside front cover) In the area of ” The Nature of Science” ( 1), under “Scientific World View”, they recommend students understand:

  • The World is Understandable.
  • Scientific Ideas are Subject to Change.
  • Scientific Knowledge is Durable.
  • Science Cannot Provide Complete Answers to All Questions.
  • The section on Scientific Inquiry begins this ways.

The section of Scientific Inquiry begins with this introduction:

Fundamentally, the various scientific disciplines are alike in their reliance on evidence, the use of hypothesis, the kinds of logic used, and much more. Nevertheless, scientists differ greatly from one another in what phenomena they investigate and in how they go about their work; in the reliance they place on historical data or on experimental findings and on qualitative or quantitative methods; in their recourse to fundamental principles; and in how much they draw on the findings of other sciences. Still, the exchange of techniques, information, and concepts goes on all the time among scientists, and there are common understandings among them about what constitutes and investigation that is scientifically valid.

Scientific inquiry is not easily described apart from the context of particular investigations. There simply is no fixed set of steps that scientists always follow, no one path that leads them unerringly to scientific knowledge. There are, however, certain features of science that give it a distinctive character as a mode of inquiry. Although those features are especially characteristic of the work of professional scientists, everyone can exercise them in thinking scientifically about many matters of interest in everyday life.(Bold print added, 4)

The book goes on to describe a number of these features:

  • Science demands Evidence
  • Science is a Blend of Logic and Imagination
  • Science Explains and Predicts
  • Scientists try to Identify and Avoid Bias
  • Science is not Authoritarian  (4-7)

Let us consider a few differences methods for different purposes.

Statistical Research

Someone notices a group of three-legged frogs. Someone notices an unusual number of childhood cancers in a neighborhood. In neither case will they do an experiment, exposing frogs or children to dangerous substances to “prove” what caused the problem. Instead, they begin by collecting data.They have begun with an important observation and questions about the cause, but they must collect data before developing a hypothesis. They may or may not be able to test the hypothesis experimentally, but a strong correlation between the occurrence of problems and the occurrence of certain environmental factors builds a strong case.

The first scientists might survey large numbers of frogs in the area in a variety of environments. If they find mutant frogs only in certain ponds, they can then study the environment in all the ponds, looking for substances only found in the ponds with mutant frogs. Does this prove cause and effect? No. But it certainly provides evidence to support a hypothesis. With frogs, they might then experiment to see if they can reproduce the effect.

With the children, the research begins in a similar way. They will collect data over a large area to see if it is true that this one neighborhood or several neighborhoods have a significantly higher number of childhood cancers. The numbers may not be different at all. It may simple be a case that parents learned about other children with similar problems and began collecting data to show a high rate of cancers. It is also true that with random occurrences like this, they will exist in larger numbers in some areas, and smaller numbers elsewhere. The researcher may also go to the next step, studying the environment in neighborhood with and without the high rates of cancer. If they discover different substances or other differences, they might test them on mice or other animals but they cannot test them on children. In many cases, they discover no dangerous substances and conclude that the numbers of childhood cancers were probably a coincidence.

Searching for New Species

One person wants to find new species of birds. Another looks for new species of plants. Yet another looks for new species of bacteria. Do they use a scientific method? Of course.

They begin with a goal, and a question about where to look. The first two might travel to a rain forest or other remote area. The bird watcher will need to study a large area with a variety of different environments (river, fresh water pond, salt pond, grassland, forested areas, and various altitudes, The bird-watcher should check these areas at different times of day and night and at different seasons.

The bacteriologist might do almost as well checking unusual areas in their backyard. They might decide to check feces or different animals, or roots of different plants.

Testing new Medicines, Household Products, Food, and Cars

My science students who had no original ideas for Science Fair Projects often tested 3-5 detergents to see which did a better job removing a series of stains. Not too exciting but much better than nothing. At the professional level this is another kind of scientific method. Medical researchers may use animals or human volunteers to tell the effectiveness of new medicines and study the side effects. Others test food products to see if they are safe. In recent years there have been studies of saturated fats and trans fats to see how they affect the body. Other companies may test cars for safety. They all understand the important of have large amounts of data, and often to be able to compare this to controls, with people taking placebos.

How do Non-scientists use Scientific Thinking?

1. We should be observant. We can observe nature, business trends, human behavior, even politicians. As we consider what we have observed, we might have questions, or even an occasional hypothesis.

2. We need to start with an open mind, free of bias, prejudice, and opinions. We shouldn’t just look for proof that our own ideas are correct. We should ask questions without preconceived ideas.

3. We need to collect evidence. We need to look for factual information from reliable sources. We should consider information from different points of view.

4. Once we have data, we need to analyze it and evaluate it. We must realize that, when we cannot actually prove something, we should never treat it as a fact but as a possibility. When we can be sure if when we find the example that proves our ideas wrong.  For example: My hypothesis is that Mei Ling cannot speak English. I may listen for months or years and never hear her say a word of English but that does not prove my hypothesis. But, if I hear her speaking English one day, I have proved my hypothesis wrong.

5. We can stay informed on recent information and ideas in science and think about ways this information might affect you or others you know.

You might also be interested in Mathematical Thinking  or     Analysis   and Synthesis

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