The Scientific Method

The scientific method is a crucial concept in understanding much of the approach of this course. It is also important in helping you to understand the difference between science (which is a subject of this particular course) and religion (which is not). As already noted, sometimes archaeology and human paleontology reach conclusions based on available information which may not be in agreement with the religious or political realities of a specific culture. [Remember, if you understand the scientific method, and science-based hypotheses and theories, you do not need to read this lesson.]

Science is based upon empirical observation. If you and I both have all five senses (no physical impairment), then anything we can both hear, see, touch, smell and/or taste is an empirical observation. Anyone, with normal senses, would make the same observation. The following story illustrates an empirical observation.Let us suppose that we walk into a dark room together. I turn on the light switch to turn on the light bulb, but nothing happens: the light doesn't go on and the room stays dark. If I say the room is still dark, and you say no, the light came on, then either something is wrong with the sight of one of us (a testable hypothesis), or else one of us is observing something that is not an empirical observation!

• Question: If you walk around making empirical observations but never ask any questions, you won't make a very good scientist. In the case of our light bulb that won't turn on, the obvious question is "why"?
• Hypothesis: A hypothesis is a tentative answer to the question. The hypothesis must be testable (some test must be possible to explore the relationship among measurable variables that relate to the question). Lots of science involves testing hypotheses that ultimately are wrong. In the case of our light bulb that wouldn't turn on, our hypothesis might be that we have a blown fuse. We have from a specific observation used induction to formulate a general explanatory principle. A blown fuse is a very testable hypothesis, and moves us immediately into the next step of the scientific method.
• Experimentation or Evidence Gathering: There may be several ways to test any hypothesis. To test our hypothesis with regard to our light bulb, we could replace all fuses and then see if the light bulb goes on. There might be an easier way, however. Lets assume we already know which fuses are related to which electrical appliances. We can then simply test to find out if other appliances attached to the same fuses are working. After testing, we establish that the problem can not be the fuse. What do we do now? Come up with another hypothesis.
• Revised Hypothesis (2):Let's assume that our second hypothesis is that the light bulb doesn't go on because the bulb is burned out. Once again, this is a testable hypothesis.
• Experiment 2: We replace the light bulb in question with a brand new light bulb. This time when we flick the light switch, on comes the light! Have we proven our hypothesis? No!! We have not actually proven that our original light bulb was burned out. [Of course, since the light is now working, non-scientific types might be satisfied and not come up with any additional experiment testing all variables.] To hopefully prove our hypothesis, we put the original light bulb into another light socket, and we find out that the bulb works just fine! Clearly, our revised hypothesis was also wrong, and we need to come up with another.
• Revised Hypothesis (3): A possible third hypothesis is that our light bulb did not light up originally because it was not completely screwed into the socket. Can we test this hypothesis? The answer is both yes and no.
• Experiment 3: With several different lamps, we completely screw in some light bulbs and incompletely screw in others. Only those lamps with completely screwed in bulbs will turn on. We have proven the general hypothesis that light bulbs that are incompletely screwed into sockets won't go on! With more experiments, we might even move to the final step in the scientific method.
• Theory: Our general theory might be phrased as follows: light bulbs which are not properly screwed into the socket won't light up when you turn the light switch on. This is a perfectly good scientific theory. It is based upon repeated experimental testing of a hypothesis. It can be used to predict the "behavior" of light bulbs, anybody can duplicate the experiment and come to the same conclusion, and it might be useful in solving future light bulb problems. Yet in this instance there is no way to prove that this theory actually explains why our original light bulb did not light up when we entered the room and flicked the switch. Since we removed that light bulb without checking to see if it was properly screwed in, we can't prove that the general theory applies in our specific case.

Now I would agree that the most likely explanation for why our bulb didn't light up is the general theory as stated above, since we have already proven that it wasn't a fuse and our bulb was not burnt out. Still, there may be other hypotheses that we did not test--perhaps because we didn't even think of them. For example, perhaps our bulb didn't go on because there were mice in the walls gnawing on the wires and causing intermittent shortages. That is a hypothesis we might never think of--particularly if there is no other evidence that we have mice. If we do think of it, we could test the general hypothesis that mice gnawing on wires can cause temporary shortages in electricity. And perhaps we could also prove that there are no mice in the walls, which would make it even more likely that our true explanation is a light bulb that is not properly screwed in. But science always has the possibility of mice in the walls: new evidence may necessitate revision of hypotheses and even revision of theories. Scientific theories, in other words, must be correctable.

I like the example of the light bulb because it illustrates several things of particular relevance to the study of human evolution, which is one of our first topics in this course. The general theory of evolution is a proven theory, in the same sense as our theory about improperly screwed in light bulbs is a proven theory. Looking at human evolution however, is a lot like trying to figure out why our light bulb didn't go on after we had removed it from the socket. We can try to eliminate as many hypotheses regarding the specifics of human evolution as we can. But at best we can only come up with a "most likely" scenario for human evolution, whose details will constantly change as new evidence becomes available. With fossil evidence however, we have already removed the light bulb.

Other types of archaeological evidence have some of the same problems. We are not actually observing and talking to the people, and certain parts of their lifestyle may not have been preserved, or we have insufficient evidence to reconstruct them.

In the end, any scientific theory must be correctable; it must be able to change as new evidence is discovered, as new hypotheses are tested. If the explanation can't be tested, and can't be corrected, it isn't science.