In the philosophy of science instrumentalism and realism define what constitutes an acceptable theory.
Instrumentalists claim that scientific theories are merely useful tools for predicting phenomena instead of true or approximately true descriptions of the physical world while realists hold the view that they should be.
As Richard DeWitt points out in his book “Worldviews: An Introduction to the History and Philosophy of Science“
“The disagreement between instrumentalists and realists as to what constitutes a valid theory goes back to the beginnings of science. Both agree that an adequate theory must accurately predict and explain the relevant data. However realists require, in addition, that an adequate theory pictures, or models, the way things really are.”
For example to an instrumentalist in Europe between AD 150 and 1500, the question “Are epicycles real?†would not have been an important question to ask because Ptolemy’s theory which involve epicycles accurately predicted and explained the observational data relevant to that time, and that is all that is important.
On the other hand, for a realist this question would be important because they are not only are concerned with how accurate a theories predictions are but on establishing the “reality” of the conceptual basis for those predictions. In other words do epicycles really exist or are they illusion created by the human intellect to explain why Ptolemy’s predictions are accurate.
This issue whether we should require theories to reflect the way things really are, which distinguishes instrumentalists and realists is just as controversial today as it was Ptolemy’s time.
For example even though the quantum mechanics with its “peculiar-looking” wave functions makes excellent predictions of quantum facts should we ask ourselves if it reflects the way things really are or accept it only on the bases that it allows us to make very accurate predictions of quantum phenomena.
This is particularly important because the wave function may be one of the weirdest inventions of the human mind to explain the “reality” of the facts or observations of quantum environment.
Weird because no one has been able to interpret what it tells us in terms of the “reality” we observe around us.
For example the Copenhagen interpretation defines the existence or “reality” of a particle in terms of the mathematical properties of a wave function that is spread out over the entire universe and tells us a particle only appears in a specific place when a conscience observer looks at it. Therefore it assumes the act of measurement or observation creates its physical reality. However because only conscience human beings can be observers it implies that nothing can exist without them being there to observe them.
However because human are made up of particles if one assumes that they exist only after being observed by a human one must also assume that humans evolved out of something that did not exist.
Clearly the Copenhagen explanation deviates from the “reality” of the observable world and the presently accepted laws of physics because up until it came along they told us that something cannot be created out of nothing.
However instrumentalists claim this is not a problem because quantum theory makes extremely accurate predictions of all observed facts regarding a quantum environment however the realist say wait a minute are you telling us that we should accept your explanation of the facts that have no resemblance to the “reality” we see around us.
Who is right?
Both the instrumentalists and realists have created valid arguments to support their positions as to what constitutes a valid theory so how should we decide.
One way to determine which is best suited to the advance our ability to accurately define what we observe in our environment would be to look at the evolutionary history of theoretical science and determine which of these philosophies provide the greatest motivation for scientific progress.
Historically most paradigm shifts in our understanding of our universe has been a result of attempting to understand what we observe in terms of the “reality” of what we see around us.
For example, new discoveries, such as those involving Galileo and the telescope, eventually led to the rejection of the Ptolemy’s geocentric model and the adoption of the more observationally corrected heliocentric one based on a new understanding of the “reality” they provided.
However even before Galileo’s observation there were suggestions that something was not right with Ptolemy’s model because no one had ever observed objects spontaneous moving backwards in what is called retrograde motion other than the planets.
This should have and did cause some to question the validity of Ptolemy explanation of planetary motion long before Galileo made his observations.
Why then did it take almost 1500 years before its validity was rejected by the majority of the scientific community in Europe ?
It may have been because the instrumentalist’s attitude of that period allowed the majority of thinkers at that time to focus primarily on its ability to make accurate predictions of where the planets would be located in the future and not on the mechanism defining how they got there.
In other words because instrumentalism was the predominate philosophy at the time, scientists were able to ignore or marginalize those who questioned the validity of the Ptolemy’s model.
Therefore one could justifiably say that instrumentalists of that period created an atmosphere that caused or gave science the ability not to explore or ignore possible explanations that were more closely agreed with the reality behind those physical observations.
This demonstrates one of the fundamental flaws in the instrumentalist’s philosophy.
By saying that a theory does not have to represent a true or approximately true descriptions of the physical world gives scientists an excuse not to look for a way explaining the “reality” or attempting to understand what we observe in terms of the mechanistic properties of the world we see around us.
Today the instrumentalist’s attitude towards understanding of reality is alive and well as is demonstrated by the wildly accepted assumptions of quantum mechanics which is based solely on its mathematically predictive ability demonstrates.
However should we trust abstract mathematics to define our understanding of reality or should we let the “reality” of observations guide our understanding of the mathematics that define it.
History has shown the pitfalls of the instrumentalist’s philosophy or basing a theories validity only on their mathematical ability to make accurate predictions of what we observe.
Later Jeff
copyright Jeffrey O’Callaghan 2012