Scientists use two different kinds of reasoning: inductive and deductive reasoning. With inductive reasoning, scientists move from the observation of a specific piece of data to develop an hypothesis about what that data might mean. With deductive reasoning, the scientist will start by suggesting an hypothesis, and then conduct research and search for data to either support or disprove the hypothesis.
For example, an archaeologist might have a theory that people in southwestern Wisconsin at 1400 A.D. sought to obtain all of the wild food that they could from the local habitat to supplement what they could grow in their agricultural fields. They might hypothesize that the people ate bullhead catfish from the Mississippi river. To test this, the archaeologists would conduct excavations in the area to look for the bones of the catfish in archaeological contexts indicating that the people had been harvesting them.
Scientists, including archaeologists, cannot "prove" their hypothesis to be correct, but they can disprove hypotheses that are incorrect. When the data supports an hypothesis, then they have more confidence in their ideas. Theories that are supported by a lot of data, and not disproved by any data, are considered powerful explanations. However, future work may require that these theories be refined or modified to account for new data. The scientific method is a never-ending process of making and refining hypotheses, continually testing them with new data, and reformulating them when new data is available.
Here are some of the steps of the scientific method that an archaeologist might use to investigate the past.
Choose a problem
Archaeologists are interested in many different aspects of how people lived long ago. They need to ask specific questions and to know what to look for when answering their questions. Examples of questions archaeologists might ask before excavating include: When did people first inhabit this area? Did the past inhabitants interact with other groups, and if so, how did they interact?
Archaeologists study books, journals, reports, and data collected by other archaeologists to find information that relates to the questions they are asking. For example, if they want to know what people ate, they need to be able to identify any plant or animal remains they may recover from the site, and then decide if they represent the remnants of food or of other activities. If they want to examine ancient trade networks, they need to know what natural resources are available in different areas that could be used for trade.
Develop a hypothesis
Archaeologists consider their research and develop hypotheses. These hypotheses are the potential answers to their original questions, so their hypotheses must be testable. One hypothesis might be that copper from northern Wisconsin was traded to other groups in southern Wisconsin and Illinois. The archaeologist would predict that copper mined in northern Wisconsin would be found in sites in the other areas.
Write your procedures
Archaeologists list the procedures they will follow in the field and in the lab, the materials they will need, and the attributes (characteristics such as color, texture, size, and shape) they will be examining. The archaeologist might consider specifically what they need to find to support their hypothesis.
Test your hypothesis
Archaeologists make observations and collect data according to the procedures they constructed. If their procedures include an excavation, they must collect all the data present at a site. They cannot collect just the information that answers their current questions because excavation permanently destroys a site. Archaeologists then organize the data collected in the field: Artifacts are washed and cataloged; artifacts, photographs, maps, and field notes are analyzed; and a report of the observations is written.
The archaeologists next look at their data to see if it supports their hypothesis. If it does, then they can have increased confidence that their idea about the past is correct. If the data doesn't support their hypothesis, then they think about alternative explanations and different hypotheses that might be testable with the data. They may need to conduct further research to test new hypotheses.
Share your conclusions
Archeologists share the information they have gathered with others through journal articles, reports, conferences, displays, brochures, videos, lectures, and Web sites. In this way, researchers learn from each other.