Since the time of Francis Bacon in the 1500s, science had been defined by inductive reasoning. This inductive scientific method — still largely in use today — gathers observational data, develops hypotheses that match patterns in the data, verifies the hypotheses through more observation, and then settles on a theory from which science can make predictions.
Inductive reasoning had its weakness, as David Hume had shown — it could never reach complete certainty. Ultimately, all science was guesswork based on available data; that’s one reason why science is tricky. To try to solve this problem, philosopher Auguste Comte (1798–1857) invented the term “positivism” to describe that to which he thought science and philosophy should aspire — positive knowledge completely devoid of speculation and superstition. Comte wanted knowledge to be only certain knowledge — positively beyond doubt.
Popper’s Positivist Quest
Karl Popper (1902–1994) argued, correctly, that scientific induction cannot yield certainty. It was dependent on observations which were always limited because, to be certain, a theory derived from inductive reasoning required observations that encompassed every possible instance. As an example, Popper said that using inductive evidence, Europeans had seen many white swans and thus developed the theory that all swans are white. Then in Australia, they discovered black swans had been there all along, disproving the result of their inductive reasoning. A scientific theory is disproved by a single contrary instance, Popper believed.
Popper was also concerned that the weakness of inductive reasoning led to what he called “non-science,” what we now call “psuedoscience.” The inexactness of science allows bad actors to use inductive reasoning to create wild theories that sound good on the surface but lack rational grounding. Pseudoscience can make claims beyond the uncertainties of regular science into realms beyond the ability to confirm by observation. An example is the pseudoscience of ancient astronaut theory that asks us to believe that aliens sparked human civilization — a wild theory that can’t be confirmed by observation.
To cure the weakness problem of scientific induction, Popper proposed the falsification principle, which declares that for a theory to be considered scientific, it must conceivably be able to be tested and proven false. For example, the theory that all swans are white can be falsified by the observation of even a single swan that is not white. Popper thought that was a way of separating science from non-science and suggested that all science be held to the falsification principle. One can never prove an inductive theory, Popper argued, so the scientist should attempt to disprove his or her theory rather than attempt to prove it.
A Carrot
Skeptics and cynics have had a rhetorical field day with Popper’s falsification principle. They accuse ideas they don’t like of violating the falsification principle, though often without much justification. Atheists especially try to lean on erroneous applications of Popper’s attempt to save science from itself.
The problem is that it is impossible to achieve definitive experimental falsifications. For one, what would constitute falsification is unclear. Popper’s example that all swans are white is disingenuous because not all theories are that simple. Probably, few nontrivial theories can be disproven easily because reality and good science are not simplistic.
Then there’s what I will refer to as the carrot example. Consider this statement of a theory.
“I am thinking of a carrot.”
How could you falsify that theory? If you say that that’s a statement rather than a theory, consider this.
“I perceive the color orange the same as you do.”
Carrots are orange (except for yellow, white, and purple ones, of course). So if I place an orange carrot in front of us, we have the same perception of it, yes? Could we falsify either the theory that we do or that we don’t?
This is a nontrivial problem for the falsification principle because all human knowledge, including scientific knowledge, is dependent upon human perceptions. It is impossible to achieve definitive experimental falsifications or confirmations of other humans’ experiences. We are, as Ludwig Wittgenstein observed, dependent on what other people share with us about what they are experiencing. It was one reason why he disagreed with Popper.
On the whole, scientific theories can’t be reducible to tests of falsification. Plus, despite the wishes of believers in scientism, not all of reality can be reduced to scientific theories. Here, I am only scratching the surface of the problems with Popper’s falsification principle. It has some useful applications, but it can’t carry the universal weight of defending science that he hoped it would.
Continuing the theme of my carrot example, reality is not one carrot or even one type of vegetable. Reality is complex and beyond simplistic declarations like the falsification principle.
“The knowledge that there is no such thing as a scientific proof should give you a very easy way to tell real scientists from hacks and wannabes. Real scientists never use the words “scientific proofs,” because they know no such thing exists. Anyone who uses the words “proof,” “prove,” and “proven” in their discussion of science is not a real scientist.”
However, scientists don’t always accept the falsification principle when it contradicts a theory they want to believe despite it being clearly falsified by evidence. Example: the expanding universe theory.