What is falsifiability and why is important to the advancement and growth of science.
Karl Poppers answers this in his book “The Logic of Scientific Discovery” by explaining how and why only those theories that are testable and falsifiable by observations add value to a scientific community.
Theories are a result of creative imagination. Therefore, the growth of scientific knowledge rests on the ability to distinguish the reality of the “real world” from one created by imagination. Therefore, according to Karl Popper only theories, which are testable and falsifiable by observations of the “real world” add to science since they are the only ones distinguishable from an imaginary one.
In the earlier article “Causality, explanation, and deductions of predictions“ Nov-01-08 we discussed the two basic components or statements Karl feels all theories must have to be falsifiable and therefore add value to a scientific community.
The first or as he calls it the “universal statement of laws” apply to the entire universe. These are more commonly called laws of nature. Newton’s law of gravity would be an example of a universal statement because it can be applied throughout the universe.
The second or singular statements are defined as ones that apply only to specific events. My car stop because it ran out of gas is an example of a singular statement because running out gas of applies only to that event.
In this article, we will discuss why adopting Karl’s definition of falsifiability with regard to these “laws” or “statements” is important for the advancement of science.
As mentioned earlier Karl feels the value of a scientific system should be dependent on the ability of its “statements” to be falsified and not on their ability to be verified. This is because it is possible to logically proceed from one true singular statement to the falsity of a universal statement even though all other singular statements may verify it.
However, determining which singular statement can result in the downfall of a scientific system is not easy as Karl points out because it is almost always possible to introduce an ad hoc or auxiliary hypotheses to successfully integrate a singular statement into almost any scientific system.
Therefore, Karl proposes that we adopt certain rules regarding how we define falsifiability with respect to theoretical statements.
The first is all ad hoc or auxiliary hypothesis added to a theory to explain a specific observation must not decrease the falsifiability or testability of the system in question. Putting it another way, its introduction must be regarded as an attempt to develop a new system which if adopted would represent a real advancement in our understanding our world.
An example of an acceptable auxiliary hypothesis is Pauli’s exclusion principal because it increased the precision and the testability of older quantum theories.
An example of an unacceptable one would be the contraction hypotheses proposed by Fitzgerald and Lorentz to explain the experimental findings of Michelson and Morley because it had no falsifiable consequences but only served to restore agreement between theory and experiment. Therefore, it did little to advance our understanding of the “real world”.
However, advancement was achieved by Relativity because it explained and predicted Michelson and Morley’s observations along with providing new consequences and testable physical effects thereby opening up new avenues for testing and falsification of the theory.
Karl also feels the same rules of falsifiability should apply to the universal statement of laws or theories that apply to the entire universe.
For example he would , as mentioned earlier consider Newton’s law of gravity to be of value to the science community because it explained and predicted “real world” observations of planetary motion along with providing new consequences and testable physical effects thereby opening up new avenues for testing and falsification.
However, I believe he would feel that string theories have no scientific value because they hypothesized the universe is composed of one-dimensional strings. However, the existence of strings is not falsifiable by observations of the “real world” because by definition they are too small to be observed. Additionally, the mathematical arguments used to support their existence have no falsifiable consequences because in most cases they can be modified to restore agreement between them and experimental findings. Therefore, there is no way to verify if the mathematical worlds created in the minds of string theorists exist in the real world.
Physics is by definition an observational science. Imagination is a very important component in its advancement however; it must be tempered with the “reality” of the observable world.
Later Jeff
‘A nice adaptation of conditions will make almost any
hypothesis agree with the phenomena. This will please the imagination,
but does not advance our knowledge.’
J Black,
Copyright Jeffery O’Callaghan 2009