Why is speculation forbidden in science?
Category: Society Published: January 27, 2014
By: Christopher S. Baird, author of The Top 50 Science Questions with Surprising Answers and Associate Professor of Physics at West Texas A&M University
Public Domain Image, source: SOHO/ESA/NASA.
Speculation is not completely forbidden in science. In fact, used at the proper stage of science (hypothesis-forming), clever speculation can be quite useful. Speculation is so easy and tempting in settings where it leads more to errors than to accurate information, that most often speculation in science is discouraged. But there is still a limited, useful, role for speculation in science. By "speculation", I mean making a statement about the physical world with near zero evidence to back up the claim. Let us look at instances where speculation is non-productive in science, and then the instance where it is productive.
Instances where speculation in science is non-productive
- Speculating when reliable data already exists.
For instance, if a friend asks you for the mass of an electron and you don't know, you can do two things to provide an answer. You can engage in speculation and most likely give a wrong answer ("An electron is small, so its mass is only a few grams"). Or you can look up the experimentally-measured answer ("Let me bring up the NIST website... it says an electron has a mass of 9.1 × 10-31 kg). In some cases, you can even perform the experiment yourself. Turning to speculation when you don't know the answer is tempting because it makes you look smart and it lets you be lazy. But if there is experimentally-measured data already available, then there is absolutely no need to speculate. In such instances, speculation will only spread misinformation. Most of the science-sounding comments and answers posted on the internet by non-experts with no reference to experimental data exemplifies this type of unhelpful speculation. With the near-instantaneous communication speeds and vast resources of the modern internet, there is no excuse for speculating when experimental data is available. The problem is often that non-experts confuse "I don't know" with "nobody knows", and thereby feel justified in spreading scientific speculation, justifying such actions with the thoughts, "my guess is as good as anybody's because no one really knows". In fact, most of the scientific questions that a non-expert encounters in everyday life have long been answered by scientific experiments. In order to avoid non-productive speculation, an honest and self-aware non-expert should never respond to a science question with the phrases "nobody knows" or "let me tell you my guess", but should rather respond with "let me look that up" or even "let's run an experiment and find out". - Confusing speculation with experimental data.
Just because no reliable experimental data currently exists on a certain subject does not mean that your educated guess carries the weight of experimental data. For instance, there is currently no experimental evidence telling us what cosmic dark matter is made out of. Scientists can detect dark matter just fine through its gravitational effects but are having difficulty determining exactly what it is. Therefore, stating in an authoritative tone that "dark matter is composed of hydrogen leaking from stars" is non-productive, especially if I try to pass this speculation off as a scientific fact. The power of speculation to misinform gets even worse when an expert in the field is doing the speculating and does not make absolutely clear that he is guessing. Because he is an expert, listeners will just assume everything he says is a summary of solid experimental findings, and will even pass his comment on as such. The pattern goes something like this: Dr. AstroExpert holds an interview with Mr. Journalist in which Mr. Journalist (in the interest of a sensational interview) is able to coax Dr. AstroExpert into freely speculating. The headline of the interview becomes something like, "Dr. AstroExpert claims dark matter comes from leaks in the sun." Readers then pass along this statement to all their friends as if it were a recently-established scientific fact instead of the unreliable speculation that it is. Since speculation is so often wrong and so easily confused with actual results, most academic journals publish only experimental results and well-developed theories that match experimental results; not speculation. - Speculating in areas where scientific measurements can't be made.
Many areas are simply outside the realm of scientific measurements and belong more in the fields of abstract philosophy or religion. For instance, questions such as "What is the purpose of life?" or "What happened before the Big Bang?" can't be answered using purely scientific methods. As such, any answer to these questions in a scientific setting is going to be highly unreliable speculation.
The only instance where speculation in science is productive
- Speculating to form a hypothesis.
The only instance in science where speculation is productive is in forming a hypothesis. Furthermore, forming a hypothesis is only productive insofar as it leads to properly-performed experiments. In this sense, speculation is only productive if it leads ultimately to experimental measurements. The results of the experiment then replace any notions that were harbored in the speculation. Speculation that does not lead to experimentation is unproductive and potentially misleading. Without clever speculation, scientists would be forced to run every possible experiment, where most of the experiments would reveal nothing new or interesting. For instance, suppose your son asks you, "What makes a pot of water boil faster?" If you just guess that adding pepper makes the water boil faster and don't test this bit of speculation, then this answer will likely be wrong and your speculation will likely be misleading. On the other hand, if you instead decide to run experiments to answer this question, but vow to avoid all speculation, you will be forced to run thousands of experiments, testing every possible additive and technique. While such an approach may ultimately lead you to the right answer, you will waste a lot of time. If you instead intelligently speculate that less water in the pot means less heat to raise the temperature to boiling, and then run the experiment, you may end up at the answer more quickly. In this way, speculation in science can be productive in deciding what experiments to run.