THE NATURE OF HISTORICAL SCIENCE
What is the scientific method?
Although different fields of scientific study have unique ways of approaching their subject, there are some basic elements that characterize the scientific methodologies.
1) Observations are made of the natural world, whether directly or through the use of instruments.
2) Perceived patterns and regularities in these observations become the basis for proposing a hypothesis to explain them.
3) A new set of observations not yet made is predicted from the hypothesis.
4) The hypothesis can then be tested against these new observations, and modified or rejected if necessary.
Although hypotheses can be rejected by the methodology of science, they cannot be positively proven in the sense of a mathematical or logical proof. The construction of scientific hypotheses is influenced by philosophical, religious and cultural assumptions of which the investigator may be unaware. However, those hypotheses are subject to test, and will not become widely held by the scientific community unless those predictions are fruitful. The more a hypothesis, or set of related hypotheses, effectively explains our observations of the natural world and productively guides future research, the greater confidence scientists have in the validity of those hypotheses. Unifying scientific theories are built up from many component hypotheses that have withstood repeated tests against observations.
Isn't science really about proven facts?
Science is not the mastery of a body of unchanging scientific "facts", but a way of inquiring about our physical environment. It provides a way of understanding, explaining, and integrating our observations of the natural world. While observations form the foundation of scientific description, serious theoretical inquiry is the essence of science. Nothing could be more deadly to science than to divorce it from the unifying theories which give observations meaning. Theories provide the predictions which suggest new observations and drive new discovery.
The history of our changing scientific understanding of the universe, with new theories replacing old, and previously accepted "facts" being overturned by new discoveries, can be puzzling to someone who has learned science as a body of facts. Furthermore, uncertainty or sharp disagreement within the scientific community are often seen as failures of science rather than expressions of its very strength.
Aren't theories about the past untestable?
Frequent claims are made that the historical sciences (cosmology, astronomy, geology, evolutionary biology, anthropology, archaeology) deal with unrepeatable events and are therefore not experimental. Furthermore, because past events and processes are not directly observable, theories of origins are deemed inferior or less certain than studies of present processes. This view commonly finds expression in statements like: "No one was there so we can never know what really happened." This view is false. The historical sciences are no less scientific, or testable, than the "hard sciences." Predictions made by hypotheses in these fields are continually being tested by new observations. Predictions are tested against each new observation or analysis. Obtaining data from a newly analyzed sample or newly described locality is no different methodologically than obtaining data from a new experimental trial. In both cases, the new observations can be tested against expectations based on previous experience and theoretical predictions. If the predictions deduced from a hypothesis are not supported by new observations then that hypothesis is modified or rejected. Scientific research proceeds by an almost continual process of hypothesis creation and testing. Many past theories in the historical sciences have been discarded with the accumulation of new observations and the development of new theories of greater explanatory power.
Like all scientific disciplines, geology and paleontology proceed by testing the predictions of existing models and theories. Predictions are tested against each new observation or analysis. Obtaining data from a newly analyzed sample or newly described locality is no different methodologically than obtaining data from a new experimental trial. In both cases, the new observations can be tested against expectations based on previous experience and theoretical predictions. In stratigraphy or sedimentology, for example, the measurement and description of each new rock outcrop or subsurface core is a test of working hypotheses based on present understanding. For example, if a specific rock unit is interpreted to be part of a meandering river system, then specific predictions can be made concerning the geometry of this rock body and the characteristics and distribution of associated sedimentary rocks. In modern meandering river systems a whole complex of sedimentary environments are present: channel and point bar deposits, levees, crevasse splays, overbank flood deposits, abandoned channels, freshwater lakes, etc. Each of these environments has its characteristic spatial relationships, sediment types, depositional features, and associated biota. If the original hypothesis of a meandering river system was correct, then further exploration and sampling of the area should reveal the predicted geologic features and their predicted spatial and temporal relationships. If the new observations are contrary to these predictions, then the hypothesis must be modified, or if necessary, abandoned.
Isn't one theory as good as another?
Many theories may be proposed to explain the same set of observations. However, not all theories are given equal weight by the scientific community. Some are rejected by the preponderance of practicing scientists, and others remain at the fringes provoking critical examination. How do we distinguish a good theory from a bad one? How do we establish relative confidence in theories? Criteria for a good scientific theory include:
1) explanatory power;
2) predictive power (testable expectations);
3) fruitfulness (ability to generate new questions and new directions of research); and
4) aesthetics (eg. beauty, simplicity, symmetry).
Biological evolution (descent with modification from a common ancestor), plate tectonics (the mobility and recycling of the Earth's crust) , and the Big Bang theory are examples of extremely well-substantiated theories that provide an interpretative framework for a vast amount of observational evidence. These powerful unifying theories continue to generate fruitful and testable hypotheses that drive new discovery.
Isn't science based on an atheistic philosophy?
The answer is an emphatic NO! Science is a methodology, a limited way of knowing about the natural world. Scientific research proceeds by the search for chains of cause-and-effect, and confines itself to the investigation of "natural" entities and forces. This self limitation is sometimes referred to as "methodological naturalism." Science does not affirm or deny the existence of a creator -- it is simply silent on the existence or action of God. The confirmation or denial of ultimate causes is beyond its capacity to investigate. Methodological naturalism describes what empirical inquiry is, it certainly is not a statement of the nature of all reality. Science pursues truth within very narrow limits. Our most profound questions about the nature of reality (questions of meaning and purpose and morality) , while they may arise from within science, are theological or philosophical in nature and their answers lie beyond the reach of science.