7.2 Hypothetical Method in Science

The article on Bacon (section 7.1) guided us through the limitations of moving from copious observations to the formulation of a general theory, and it reinforces that while the method was practiced and appreciated, it has not always served as a primary method for doing science, even in the past. And Adam Savage’s TED-Ed video (section 7.1) corroborated the notion that scientific progress often starts with imagination and creative ideas (hypotheses) that influence the direction for observations, fact-gathering, and testing. The Hypothetico-Deductive (H-D) method (or simply the hypothetical method) is a model for the process of scientific discovery that differs from Bacon’s method. The process involves hypothetical reasoning, that is, the formulation of a testable hypothesis to explain something.

Inferring a simple and likely explanation (a hypothesis) for some problem or observation is sometimes referred to as abduction,  (a term that comes up in the assigned, upcoming video. ) It is not a deduction because there is no certainty of the explanation’s truth. And while being akin to induction, given the absence of certainty, abduction is distinguished from induction in this way — abduction proposes a best explanation, whereas induction makes actual specific claims (that are highly probable at best.)

The following video,  Hypothetical and Scientific Reasoning with Dr. Jacob Waldenmaier, presents course content on the hypothetical method in science. Watch at least the first 28 minutes; the last topic on the null hypothesis is part of our course material.

It’s important now to review some key points made about the scientific method.

What is a Hypothesis?

• A hypothesis is a tentative theory that requires further information or verification to confirm it or deny it.
• A hypothesis must be rejected if/when tests or observations do not support it; a hypothesis is strengthened when tests or evidence do support it.

Types of Hypotheses

• Theoretical hypotheses are proposals about how we should conceptualize something. This might involve principles, rules, or a model that can account for large amounts of data.
• Empirical hypotheses propose the existence of something that is detectable or measurable.

The Basic Steps of the Scientific Method

1. Identify a problem or question.
   This is where we articulate, as clearly as possible, the phenomena or situation we hope to explain. Why does the ball roll to the back of the wagon when we pull forward? Or why does Uranus not travel its expected orbital path?
2. Form a hypothesis to explain the problem or question.
   This is our abductive move – we formulate the best possible explanation, one that will require further investigation and information to confirm or deny it.
3. Identify the implications of the hypothesis.
   This is where we use hypothetical reasoning: If this hypothesis were the case, then these are its implications (that is, what we expect to observe or to have our tests reveal.)
4. Test the implications.
   This step entails doing the work to see if the expected results (implications) occur. With an empirical hypothesis, this typically involves observations or measurements. For a theoretical hypothesis, testing might include mathematical calculations involving vast amounts of data.

Keep in mind that some deductive logic underlies the procedural steps and success of the scientific method.

The Logic of Falsification: As explained in the video, an inherent aspect of the scientific method is the discovery that a hypothesis may be incorrect. The common valid deductive argument form, modus tollens, (see Some Common Deductive Argument Forms at the end of Module 1) helps to illustrate the logical basis on which the scientific method rejects a hypothesis. Let ‘H’=hypothesis, and ‘E’= expected result from testing an implication of the hypothesis:

or in sentential form:

So suppose we perform a test and do not get the expected result. ‘E’ is not true, thus, ‘H’ is not true. The hypothesis must be rejected or reworked, and the process starts again.

The Logic of Confirmation: On the other hand, suppose tests or observations do meet implied expectations. This compatible outcome strengthens the hypothesis and lends it credibility, but it does not prove that H is true. Here is the logical representation, again using ‘H’ and ‘E’:

or in sentential form:

This is an invalid argument form, it is the one used in 2.2 Logical Fallacies, Formal and Informal, ‘Example 1’. This is the fallacy of affirming the consequent. We used a counterexample to demonstrate the invalidity of this argument form.  In our confirmation scenario, the expected result E from testing the implication might be the direct result of the hypothesis, but E may have occurred for some other reason – we cannot be certain.

Still, however, when expected results occur repeatedly, these are steps forward. Every new test/observation found to match implied/expected results adds to the strength of the hypothesis. As time goes by, when no test is found to falsify the hypothesis, it may become accepted, at least tentatively, as a theory.