How do we know what is true? It’s an age-old question that hasn’t been fully resolved.
We do know that evaluating evidence and recognizing the role of subjectivity are part of the most reliable approach we’ve discovered so far in our trajectory as a species.
Generally, we call this approach “science.” But science is not the same as truth.
A few years ago, the American Anthropological Association (AAA) removed the word “science” from its description of the discipline of anthropology. Unsurprisingly, this act created an uproar with partisans on either side arguing for or against the definition of anthropology as a science.
Unfortunately, a lot of them seemed unable to articulate what science really is.
It’s a common mistake and one you will encounter in other areas. When people debate the validity of science, we tend to take for granted that everyone knows what the term means. Fun fact: we don’t.
You may have come across the phrase “the scientific method.” This phrase provides a clearer indication of what’s going on than the single word “science.” “Science tell us that the Earth orbits the sun” would become “The scientific method tells us that the Earth orbits the sun.” It’s a subtle difference, but revealing nonetheless.
The first statement implies some sort of oracle or god (“Science, goddess of the Sky”) revealed an absolute truth. In the second version, we understand that a rigorous process was involved.
In the early twentieth century, anthropologist Alfred Kroeber (drawing on his teacher Franz Boas) wrote down three principles of science:
The method of science is to begin with questions, not with answers, least of all with value judgements.
Science is dispassionate inquiry and therefore cannot take over outright any ideologies “already formulated in everyday life”, since these are themselves inevitably traditional and normally tinged with emotional prejudice.
Sweeping all-or-none, black-and-white judgements are characteristic of categorical attitudes and have no place in science, whose very nature is inferential and judicious.
Kroeber’s teacher, Franz Boas, divided science into two branches, which he called the general sciences and the historical sciences. For him, the general sciences try to discover universal laws, while the historical sciences uncover the processes behind things that happen only once, usually in a specific time and place. The social sciences, including history, linguistics, sociology, and anthropology (among many others), fall into the latter category.
Both use the scientific method. Although the type of knowledge they produce is not identical, both the general sciences and the historical sciences contribute “true” ideas to the collective body of knowledge.
I put “true” in quotation marks because scientists of all stripes constantly work to disprove accepted theories. When evidence supports a theory, that’s great, but it’s more important to see what other evidence might disprove the theory. In this way, while it is a challenge to conclusively prove a scientific theory beyond any possibility of dispute, it can be quite simple to disprove the same theory. This is how we know that vaccines don’t cause autism (a disproven theory) and that gravity is likely more of a push than a pull (a theory modified from its original version).
As The Skeptical Raptor suggests, evidence against a hypothesis is more powerful than evidence in favour of it. In other words, if you have three bits of evidence in favour of a theory and only one against it, the theory is wrong. It might not be entirely wrong (as in the gravity example above), but something about it needs to be changed to more accurately represent what is happening.
This is why so-called scientific laws are not carved in stone. Just like national laws, they can change.
Scientists face a lot of criticism when they announce that they were wrong about something. Also when they refuse to state anything with 100% certainty.
But what they are trying to say is that, while there is no absolute truth, there are degrees of validity.
Additionally, a theory is only based on the scientific method if people can imagine a way to test or disprove that theory.
If there is no way to test it, then there is also no way to prove it or argue it either way. We’ve left the realm of science to enter the realm of philosophy (which, by the way, has a lot of value in its right).
One of psychoanalyst Sigmund Freud’s more infamous theories says that all girls experience penis envy, recognizing the male sex organ as superior to their own. When challenged with evidence that went against his theory, namely that many girls and women say they do not have penis envy, Freud simply asserted that they were in denial.
This is an example of how logic can fail us by denying or explaining away contradictory evidence. Evidence is more important than logic and the hypothetical plausibility of a theory based on logic alone says little about how a process might actually play out in the real world. We can imagine all kinds of logically possible beings, processes, and events. Both Freud’s theory and his explanation of contradictory evidence sound logical and plausible. But as soon as he explains away the gaps with circular logic that draws on no evidence, the theory stops being scientific. You can no longer falsify (i.e. come up with a way to test his theory) since there is nothing observable (i.e. no evidence). We are forced to toss the whole thing out the window.
Real scientists and seekers of knowledge are always trying to disprove their own theories. They don’t need something to be right just because they have always thought it must be true. Instead, they constantly re-examine their assumptions and come up with new ways to disprove existing explanations.
Of course, if people test a theory for decades and centuries with no successful disproof, then the theory generally becomes established as fact. In careless everyday speech, many people including scientists will say it is therefore “true,” but I would recommend being more specific in what we say. Otherwise, we risk obscuring that in this context the word “true” simply means “rigorously tested but never disproven.” If contradictory evidence surfaced, we would accept the error in the original theory.
Science requires a flexible mind, as well as an acceptance of uncertainty.
On a final note, I use the word “disproof” above, which is probably more recent incarnation than the word “proof.” Originally, to “prove” something meant to test it, as in its derivative word “probation.” Knowing this helps us understand what the scientific method means by proving something is true – it actually means the opposite of what we might think: you can only prove a theory by seeking to show it is false, but failing to find evidence that goes against it.