Section 1.2:
The Nature of Scientific Inquiry

Learning Objective

Discuss the nature of scientific inquiry, including the construction of hypotheses and the development of theories.

Section Content

Developing an understanding of how science is done and how scientists work is an important theme in this book. As members of a modern society, we are constantly reminded of the benefits derived from science. But what exactly is the nature of scientific inquiry? Science is a process of producing knowledge. The process depends both on making careful observations and on creating explanations that make sense of the observations. The types of data that are collected often help to answer a well-defined question about the natural world, such as “Why does fog more often develop on cool clear nights, rather than warm overcast nights?” or “What causes rain to form in one cloud type, but not in another?”

All science is based on the assumption that the natural world behaves in a consistent and predictable manner that is comprehensible through careful, systematic study. The overall goal of science is to discover the underlying patterns in nature and then to use the knowledge gained to make predictions about what should or should not be expected, given certain facts or circumstances. For example, by understanding the forces that influence the movement of air, meteorologists can predict the approximate time and place of the passage of a cold front, which causes temperatures to drop.


A scientific hypothesis is a proposed explanation for a certain phenomenon that occurs in the natural world. For such an explanation to be considered a hypothesis, it must be testable. Therefore, before a hypothesis can become an accepted part of scientific knowledge, it must pass objective testing and analysis. This process requires that predictions can be made based on the hypothesis being considered. Put another way, hypotheses must fit observations other than those used to formulate them in the first place. Hypotheses that fail rigorous testing are discarded. The history of science is littered with discarded hypotheses. One of the best known is the Earth-centered model of the universe—a proposal that was supported by the apparent daily motion of the Sun, Moon, and stars around Earth. More detailed astronomical observations disproved this hypothesis.


When a hypothesis has survived extensive scrutiny and when competing hypotheses have been eliminated, it may be elevated to the status of a scientific theory. In everyday language, we may say that something is “only a theory.” But among the scientific community, a theory is a well-tested and widely accepted view that best explains certain observable facts.

Some theories that are extensively documented and extremely well supported by data are comprehensive in scope. An example from the Earth sciences is the theory of plate tectonics, which provides the framework for understanding the origins of mountains, earthquakes, and volcanic activity. It also explains the evolution of continents and ocean basins through time. As you will see in Chapter 14, this theory also helps us understand some important aspects of climate change through long spans of geologic time.

Scientific Inquiry

The processes just described, in which scientists gather data through observations and formulate scientific hypotheses and theories, is called the scientific method. Contrary to popular belief, the scientific method is not a standard recipe that scientists apply in a routine manner to unravel the secrets of our natural world. Rather, it is an endeavor that involves creativity and insight. Rutherford and Ahlgren put it this way: “Inventing hypotheses or theories to imagine how the world works and then figuring out how they can be put to the test of reality is as creative as writing poetry, composing music, or designing skyscrapers.”

Scientists have no fixed path that leads unerringly to scientific knowledge. Nevertheless, most scientific investigations involve the following:

Figure 1.7
Observation and measurement are basic parts of scientific inquiry

Automated observing systems, like the one shown, are designed to measure cloud coverage; take temperature and dew-point measurements; determine wind speed and direction; and even record present weather—such as whether it is raining or snowing.

Some scientific discoveries result from purely theoretical ideas that stand up to extensive examination. Some researchers use high-speed computers to simulate what is happening in the “real” world. These models are useful for dealing with natural processes that occur on very long time scales or that take place in extreme or inaccessible locations. Still other scientific advancements have been made when something totally unexpected happened during an experiment. These serendipitous discoveries are more than pure luck; as the nineteenth-century French scientist Louis Pasteur said, “In the field of observation, chance favors only the prepared mind.”

Scientific knowledge is acquired through several avenues, so it might be best to describe the nature of scientific inquiry as the methods of science rather than the scientific method. In addition, it should always be remembered that even the most compelling scientific theories are still simplified explanations of the natural world.

You might have wondered . . . 

How do a hypothesis and a theory differ from a scientific law?

A scientific law is a basic principle that describes a particular behavior of nature that is generally narrow in scope and can be stated briefly—often as a simple mathematical equation. Because scientific laws have been shown time and time again to be consistent with observations and measurements, they are rarely discarded but may require modifications to fit new findings. For example, Newton’s laws of motion are still useful for everyday applications (NASA uses them to calculate satellite trajectories), but they do not work at velocities approaching the speed of light. Einstein’s theory of relativity is instead applied in these circumstances.

Section Glossary

Section Summary

Section Study Questions

Try to answer the following questions on your own, then click the question to see the correct answer.

How is a scientific hypothesis different from a scientific theory?

A scientific hypothesis is a tentative untested explanation regarding a natural event or process. A scientific theory is an explanation that has been tested many times by comparisons to measured data. Among the most important tests that a theory must pass is that of prediction. 

A successful theory must be able to correctly predict the nature of data or observations that are not otherwise known. 

Summarize the basic steps followed in many scientific investigations.

The basic steps would be: (1) A question is raised about the natural world; (2) scientific data are collected that relate to the question (Figure 1.7); (3) questions are posed that relate to the data, and one or more working hypotheses are developed that may answer these questions; (4) observations and experiments are developed to test the hypotheses; (5) the hypotheses are accepted, modified, or rejected, based on extensive testing; (6) data and results are shared with the scientific community for critical and further testing.