What is the Scientific Method?

How is it used and what does it do?

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Science is effectively defined by the method which actual scientists use in order to make discoveries and generally produce knowledge about the universe around us. It is this method which distinguishes the scientific process from other, generally less successful, attempts to produce knowledge about the world. Therefore, understanding science requires understanding how the scientific method works.

What is described here is, to be honest, an ideal - actual scientists do not always follow the description here perfectly, but the practice of science is nevertheless often close to the broad outlines of the ideal. It is important, however, to understand that neither the reality nor the ideal is some special or magical mental process unavailable to non-scientists.

The scientific method involves a combination of induction and deduction, each feeding back upon the other. The first part, known as the Method of Induction, is the process by which we take particular information from our senses and attempt to produce general statements about our world. For example, when we observe that fire consistently burns our fingers, we can conclude fire is generally too hot to touch.

The deductive aspect of the scientific method moves in just the opposite direction: it involves taking a general principle about the world and deducing what will or should happen in some particular instance. Thus, working from the principle that fire is too hot to touch, we can deduce that putting our foot in a fire will cause burns and pain.

Because the scientific method involves a feedback loop of induction and deduction, it often isn't possible to determine where any particular process has started - this is, in fact, one place where the practice and ideal diverge. Nevertheless, a common starting point is used here in these six steps:

1. Observation:
Some aspect of the world is observed by us and we arrive at new knowledge. This information might be obtained through any or all of our senses, and it may come to us either through our intentional efforts or accidentally.

2. Repetition:
Not much can be done with a single observation (usually); thus, more observations are necessary before proceeding further. Often these new observations are obtained deliberately as part of an effort to confirm or refute the initial observation in step #1. Our observations are often stated in the form of a question or problem, for example: In situation S, why does X always occur?

3. Induction:
After arranging and considering our observations, we attempt to create some general principle which both describes what happened and, more importantly, explains why it happened. This principle should ideally be framed as broadly as possible and is generally called a hypothesis.

4. Deduction:
Now that we have what we hope is a general principle which accurately describes and explains things which happen in our universe, it is time to do some tests to see if we are correct. This is accomplished by creating predictions - these are phrased as statement in the form "if principle P is true, then event E should occur or fact F should be true."

5. Testing:
Once we have predictions, it is time to go out and actually see what we find by collecting more observations. We try to determine if some fact (F) is already true about the world or if some event (E) occurs or can be caused to occur.

6. Induction (again):
After we produce more observations, it is time to take another look at the general principle we formulated earlier. If our predictions were true, then our hypothesis has been made stronger. According to some, once this successful testing has been repeated multiple times, the hypothesis should be called a 'scientific theory.' We now might want to start looking at making our theory broader so that it can account for more diverse phenomena.

If, however, our predictions were not successful, then we must consider what went wrong. Possibilities include: our theory was mistaken and we need to reformulate it; our deductions from the theory were mistaken and we need reconsider our understanding of it; or finally, our experiments were flawed and we need to try again.

Notice that all three of those possibilities are, in fact, theories which might explain some observed phenomenon: the failure of our experiments to confirm our original theory! So, figuring out which of them is correct will involve going through the above process and using the scientific method all over again.

Hopefully it is clear from this description that this method is ordered and that the given order is important. If you hypothesize before observing and stating a problem then you are not really being scientific; and you obviously can't test a hypothesis unless you have a hypothesis to test. Moreover, this is an iterative process: testing frequently will provide new information even if the hypothesis fails the tests. If the testing stage fails, you may go back and refine the hypothesis, or go back to analysis to reconsider the problem, then progress forward through the stages again.

Sometimes you may go back to the observation stage from the induction stage if you discover that stating a clear solution to the problem is difficult. Thus it is possible to move backward through the process as well as forward. Moreover, the process can be hierarchical: each stage of the process may involve using the scientific method to solve sub-problems or related problems. So, while the overall process is fairly simple, there can be a great deal of detail and complexity in its operation.

If all of the above sounds too difficult to grasp, rest assured that in reality it's not. As a matter of fact, the scientific method is only a formalized description of what people do every day. It is not too far wrong to say that the scientific method, even when described technically, amounts to systematized common sense. To see how and why, consider the following example, used by Tim M. Berra in his book Evolution and the Myth of Creationism. First will be the simple description and second will be the formal description:

1. You walk into a room in your house and flick on the light switch, but nothing happens. You flick it a few more times to make sure it isn't working and then go get a replacement bulb. After you put it in, you find that it still doesn't work. Looking around at the other electrical appliances in the room, you don't see any of them working either, so you go down to the basement to check the fuse box.

2. You walk into a room in your house and flick on the light switch, but nothing happens. At this point, you have an observation: the light isn't coming on. Immediately you form a hypothesis: the connection isn't making proper contact. You predict that, if this hypothesis is true, then it may be possible that it will make a connection with further attempts, so you try the switch again several times.

Unfortunately, your experiment does not produce the results you hoped for, thus your prediction fails. Your experiment was valid and your understanding of the principle is probably valid, so you have to go all of the way back to the beginning to try a new hypothesis: the bulb is burned out. If that is true, then replacing the old bulb with a new one should produce light, so you go to fetch a new bulb.

Once again, your experiment fails; once again, your experiment and your understanding of your hypothesis were probably valid, so you need yet another theory. Looking around, you make the new observation that nothing else in the room is working, so you theorize that the power to the room must be interrupted. You also predict that, if this is true, you will find evidence of that in the fuse box, so you go down to the basement to check.

Both of the above are descriptions of the same series of events, with the latter simply being much more explicit about the background processes which we are almost always unconscious of. The scientific method is more formalized and explicit than how we proceed in our everyday lives, because first, it is important that nothing be missed accidentally, and second, it is important that others be able to replicate our steps in order to determine whether or not our results are valid.

It is also worth noting where this practice diverges from the ideal - for example, a hypothesis is formulated after a single observation rather than after several. Although multiple observations are preferable, sometimes just a single observation or even just a single idea is enough to begin the process of formulating hypotheses to test. There are no absolute requirements as to what we need before we start theorizing about what happens in our world.

More: Scientific Theories

Lance F. contributed information for this FAQ entry.