Science Investigations

Keeping Records

An important part of being scientific is keeping records because it helps you to report to others accurately and honestly about your observations. Record keeping helps people to check up on you, and the knowledge that others will check up on you helps to keep you from letting your prejudices affect your results.

Being Objective

"Objective" is the word we use to mean keeping our prejudices or biases under control. Being objective means that your findings are not shaped by your feelings or prejudices but by direct observation. It means that others who make similar observations will find that they can agree with you, even though they may have different feelings or prejudices about the results of the investigation. When observers can agree on the results, in spite of their varying prejudices, the results can be called objective. This, then, is why your records are important and why you must plan to report to others on both your methods and your results.

Being Selective

How can we be sure that the things we choose to know, choose to learn, are a good, a true, and a valid selection of all the possible things there are to know? All of our past experiences come to bear on this choosing and this valuing. Our experiences with other people also help to determine our attitudes and values. In addition, experiences related by other people bring us new things to learn. However, some of the knowledge we get from others is valuable and some of it is not. How do we decide which is which?

A living human being has countless experiences every moment. Some experiences take place within ourselves, and others involve ourselves and the surrounding environment. But we cannot possibly notice, observe, or report on all of these experiences, even though they may be changing us in many subtle ways. One cannot notice every heartbeat, every leaf falling, every mosquito buzzing, every drop of rain. And so we select the things we will notice or observe about ourselves or our environment.

Thus, because we make selections, we find that we observe our surroundings with bias or prejudice. What you select to observe, another person may completely miss. Or what you fail to observe one time you may closely study another time.

What's Wrong With Common Sense?

The name for the things people claim to know, true or not, as a result of ordinary, widespread experience is common sense. We must use this term carefully. It has two widely different meanings: (1) A person who makes careful judgments based on sound information is said to use common sense. (2) Any ideas or concepts that are widely accepted by many people but that have not been carefully tested for their truthfulness are also called common sense (or common knowledge).

Common sense, for example, might suggest that heavy things fall faster than light things. Many people accept this statement as true, although a little careful thought should show that it is not a good statement, even without scientific testing.

There are many other commonsense ideas—some good, no doubt, and some not so good—and all of them needing testing. Why can't we just accept commonsense principles as okay?

The problem with taking a casual or commonsense approach to the example of whether heavy things fall faster than light things is that there are too many variables. What do we mean by too many variables? In our example you can see that people observe "light" things, such as feathers, dead leaves, and inflated balloons, as falling rather slowly. And people observe "heavy" things, such as rocks, metal tools, and chunks of wood, as falling rather fast. So they conclude, "Heavy things fall faster than light things." Scientists would say that these people have not noticed that there are two or more variables confounding the results.

The following experiments can help us test the commonsense principle that heavy things fall faster than light things. They will show how size (or area) is an important variable.

A toy balloon, when inflated, is light of weight and, yes, it falls slowly. If compared to a rock, we must agree that the rock falls faster than the balloon. But we can see two main differences or variables: (1) difference in weight and (2) difference in size or area. We can take a balloon and easily arrange for an experiment with one variable only—size or area. We simply use the same balloon for both trials, first inflated, then deflated, in each trial dropping the balloon from the same height. In doing so, we observe that the balloon inflated (larger area) falls more slowly than the balloon deflated (smaller area), even though their weights are about the same.

We can make an even better experiment if we use two balloons of the same shape and size, one inflated, one deflated, and drop them side by side at the same time from the same height.

We can plan another experiment with balloons in which size or area is the same and weight is the variable. Use two balloons of the same size and shape. Make one heavier than the other by putting a weight into it, for example, a penny. Inflate the two balloons to as nearly the same size as possible and drop them from the same height, taking care to release them at precisely the same time. We see that the heavier balloon does fall faster. Now we have one experiment that does not support the commonsense principle and one that does.

A third experiment is needed, using an inflated balloon and a piece of metal, for example, a paper clip, that is lighter than the balloon. Drop the inflated balloon and the paper clip from the same height at the same time and observe the results. In this case, the lighter object (the paper clip) falls faster than the heavier object (the balloon). So, by conducting three rather simple experiments we have observed all of the following:

1. Two things of the same weight falling at different speeds
2. A heavier thing falling faster than a light thing
3. A lighter thing falling faster than a heavy thing

As a result of this conflicting evidence, we could conclude that something is wrong with the commonsense statement that heavy things fall faster than light things. This statement is too simple to cover the varying results of our three experiments.

One might go further by experimenting with objects that are heavier than balloons, as Galileo, the great seventeenth-century Italian scientist, is thought to have done. An example would be to compare the falling speeds of two wooden balls of the same size and shape but of different weights with one ball hollowed out and filled with lead. Also, one might use more complicated equipment to create a space without air (a vacuum space) and arrange for two objects to be dropped at the same time, one with a vacuum space, to compare their falling speeds.

After enough good experimenting and observing, one might finally make a statement that would correctly express the falling speeds of things light and heavy, large and small, in air and in vacuum. We see, however, that when many variables are present all at once, as in ordinary observation, the results are what scientists call "confounded." They are mixed up too much for the simple, commonsense statement to be accurate.

Not only are there too many variables for truthful results in much common observation but also there is often too much chanciness. For example, common explanations for catching a cold are: "I got my feet wet" or: "I sat in a draft and got chilled." These explanations have been shown through careful testing to be unreliable causes of colds. However, people may get their feet wet or get chilled by a draft at just the "right" time for it to seem that one of these events caused a cold. This kind of chance happening of events at certain times and places often seems to confirm a commonsense principle, even though better testing may show the principle to be wrong.

It will not do, however, to say that all commonsense principles are wrong. Many have a grain of truth, although it may not be clear which are the truthful parts and which are not until someone performs tests good enough to be called scientific.

Anecdotal Evidence

Another kind of evidence to take a closer look at is often called anecdotal evidence. Sometimes a person brings to a discussion a story out of his or her personal experience as evidence to support a proposition. Such a story (or anecdote) may seem very convincing to the person telling the story and to his or her listeners. Nevertheless, as evidence, the anecdote may have all of the weaknesses of common sense. The events described in the anecdote may have happened suddenly, without plan, and the person telling about the events may have had only a narrow, prejudiced view of what happened.

But suppose a person is honest and accurate in giving the anecdotal evidence. Suppose, let's say, that a man took vitamin "Z" all winter and did not have a single cold, while people all around him had the usual colds. Are we going to accept this anecdote as evidence that vitamin Z prevents colds? Not likely. There is a chance that the man might have gone through the colds season without catching a cold, even if he had not taken the vitamin. It takes a broader and more thorough investigation of this sort of situation before we can conclude that we have established a good general principle. And so we must be wary about accepting anecdotal evidence because of its chanciness as well as the possible prejudiced nature of the observations.

There is a place, of course, for what is called naturalistic observation, the study of people and things under natural conditions. But one must have a plan for how to make the observations objective and the results reliable. We will consider these methods further in the next chapter, "Scientific Methods."