Primer: The Scientific Method

These posts, tagged “Primer,” are posted for two reasons: 1). to help me get better at teaching non-scientists about science-related topics; and 2). to help non-scientists learn more about things they otherwise would not. So, while I realize most people won’t read these, I’m going to write them anyway, partially for my own benefit, but mostly for yours.

There are quite a few things that go flying by in the news that concern me (and I have posted about them here…at…length…), but one that really gets to me is public misunderstanding of Science.  As in, capital “S” Science.  Not really the fact that many people don’t know certain scientific facts, or don’t really understand how many things work, but more that they do not understand how science is done and what it really means.  I will seek to clear up some of that here.

First, however, what does tell us?

Science – noun

1. a branch of knowledge or study dealing with a body of facts or truths systematically arranged and showing the operation of general laws: the mathematical sciences.
2. systematic knowledge of the physical or material world gained through observation and experimentation.
3. any of the branches of natural or physical science.
4. systematized knowledge in general.
5. knowledge, as of facts or principles; knowledge gained by systematic study.

Now, this definition seems to center upon the natural/physical sciences, however many, if not all, of the principles that “science” adheres to apply to the social sciences (e.g. sociology, psychology, etc.) and to many other degrees.  However, I will focus on what I know best.

“Systematically” is the word sprinkled about in the definition above, and rightfully so.  “Systematically” refers to how science is conducted, generally through what we refer to as the scientific method.  The Wikipedia article, as usual, is a good start for further information on this particular subject, but basically, here’s how it works:

  1. Formulate a hypothesis
  2. Test the hypothesis through experimentation and observation
  3. Use collected data to confirm or refute the initial hypothesis
  4. Form a new hypothesis based on what was learned in steps 1-3

A “hypothesis,” put simply, is an educated guess toward a question you have.  Many times, especially when you’re first learning the scientific method, you may phrase it in the form of an “If/Then” statement.  For example:

If I drop this rock, then it will fall

The “If” portion of the above statement represents the “Independent Variable,” while the “Then” portion represents the “Dependent Variable.”  Effectively, the Dependent Variable is what you’re measuring and the Independent Variable is what you’re changing in the system.  In this particular case, if you drop the rock, does it fall or not?  You can measure whether or not it falls.  If you don’t drop the rock, does it still fall?  And so on.  It is called the Dependent Variable because it “depends” on what you do in the Independent Variable.

You are generally allowed to have multiple Independent Variables in a given hypothesis (or series of hypotheses), but the Dependent Variable cannot change. What would happen if I dropped a rock on Earth and dropped another one on Mercury?  My results wouldn’t be comparable, because I changed too many things.  I could change the size of the rock, but if I’m measuring the rate at which the rock falls to the ground, I need to make sure the force of gravity is held constant.

Obviously, this is a very simple example.  If one were to ask something a bit more complicated, you could ask the following:

If Tylenol is administered to people with headaches, then they will experience pain relief.

The question above seems simple enough, right?  I could just give Tylenol to a bunch of people with headaches and see if we get an effect.  Then I would know if my hypothesis was correct or if it wasn’t.  But what would happen if I grabbed people prone to migraine headaches were participating in my study?  Or alcoholics (that don’t break down Tylenol all that well)?  The data I would receive would be flawed, as the Tylenol probably wouldn’t do anything to people with migraines and it may actually make alcoholics feel worse.  My hypothesis would be proven wrong.

Here is where we really need to consider “Controls.”  These are a separate series of experiments that you use to compare your experimental results to.  You may choose to set this up in your experiment in a variety of ways, but one possibility is to give those with migraines or the alcoholics (and all other test subjects) a “placebo,” or something that looks like Tylenol, but is actually inert.  Then, you can compare your responses to see if Tylenol had any effect or not.

Above, I mention that after you formulate a hypothesis, you must test it.  You must test it by holding as many things constant as you can while only varying a specific aspect of the experiment, especially an aspect that you can control to some degree.  This brings us to the idea of “testability.”  In order for your experiment to be considered “Scientific,” it must be testable.  If it isn’t “testable,” then it doesn’t satisfy the “systematic” part of the definition.

Over time, enough experiments are done to warrant considering a certain concept to be a “Scientific Theory.”  That is to say, a Theory is an idea that is supported by an array of evidence and co-exists with other known Theories that are equally verified by experimentation.  Assuming a Theory stands the test of time, it eventually is considered to be a “Scientific Law,” meaning it represents something truly fundamental on which the rest of science and knowledge rests.  An example of a Theory is “The Theory of Natural Selection.”  An example of a Law is “Newton’s Laws of Thermodynamics.”  Wikipedia also has a nice list of other Scientific Laws.

Most Laws tend to be Physics/Chemistry-related, as these are the bedrock concepts upon which everything else stands.  You can’t really study Biology without fluid dynamics and quantum mechanics (well, you can ignore them for the most part, but they do get involved in certain situations).  Theories, on the other hand, are much less clear cut.  They tend to represent a constantly evolving field of research, where new data is being applied every day.  I will steal the US National Academy of Sciences definition to explain more fully:

Some scientific explanations are so well established that no new evidence is likely to alter them. The explanation becomes a scientific theory. In everyday language a theory means a hunch or speculation. Not so in science. In science, the word theory refers to a comprehensive explanation of an important feature of nature supported by facts gathered over time. Theories also allow scientists to make predictions about as yet unobserved phenomena.

A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. Such fact-supported theories are not “guesses” but reliable accounts of the real world. The theory of biological evolution is more than “just a theory.” It is as factual an explanation of the universe as the atomic theory of matter or the germ theory of disease. Our understanding of gravity is still a work in progress. But the phenomenon of gravity, like evolution, is an accepted fact.

So in some ways, a Theory is treated on almost the same plane as a Law, but they really aren’t the same thing. A Theory can still be modified, while a Law is much, much harder to change.  In that first sentence, it says “no new evidence is likely to alter,” meaning you could still alter it, but it’s highly unlikely.

My overall concern with perceptions of what Science is stem from the various debates over climate change, evolution, stem cell research, etc.  In many ways, much of the political hubbub is regarding something that Science isn’t equipped to answer.  By definition, it can only give you a fact – it is up to the individual to decide how to apply their morals to that fact.  Science can tell you that Evolution is happening and that Natural Selection is the current Theory to describe how it happens.  It’s a “Theory” because more data is getting added every day, but the Theory is only strengthened, not weakened.  Overall, Natural Selection is what happens.  End of story.  Scientifically, embryonic stem cells come from an embryo, which is a collection of cells that does not fit the accepted definition of “alive” (i.e. self-awareness, self-preservation, consciousness).  Whether or not you agree that an embryo is not alive is up to you to decide, but arbitrarily suggesting that “Science says that it’s a life” is incorrect and a misuse of the term.  Saying that there are “gaps in the geological record,” so that must mean that God exists and God created the Earth in 6 days, ignores how Science works – God is, by nature, “untestable,” and therefore beyond the purview of Scientific understanding.  These are but a few of the examples of how some would misunderstand Science and try to apply it to things that it shouldn’t be applied to, or at least in ways it shouldn’t be applied.

The Study of Science is a systematic, logical progression that involves the formulation of a testable hypothesis, where testing involves experimentation, observation and collection of data to support or refute the hypothesis.  Hypotheses around a general subject can eventually add up to a Theory, and truly fundamental observations of the natural world become Law.  That’s all it is, folks.  No more.  No less.

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