This post relates to the previous post here, as well as posts on light conventions here and here.
There comes a point in science in which a convention needs to be adopted in order to avoid confusion and ensure consistency. The tendency, however, is to think that the convention adopted is real, that is, that reality uniquely matches the convention. But that is an illusion since a different convention can legitimately be adopted.
This happens more often that we might realize. I have not tried to catalog all the conventions of science but here are some:
- Units of measure. These are all conventions, and there are variations such as the inch-pound units.
- Statistical significance. A p-value of 0.05 is often used, but it is a convention, not statistics.
- Negative charge of the electron. The current and the flow of electrons are in opposite directions.
- “A rod is undergoing tension. Is this negative or positive? In steel and concrete studies, tension is positive. In soil studies, tension is negative.”
Some of these conventions are a matter of choosing a value as the standard, others involve selecting a positive and a negative type (direction, charge). The positive type would seem to be the main or default one, as with arithmetic, but this may not be the case.
The conventions on the one-way speed of light show that the question relates to the status of the observer. Is the observer always right? That leads to one convention, in which the incoming speed of light is instantaneous. Is there an average that is right? That leads to Einstein’s convention, in which light travels at the average of the two-way speed of light.
Scientifically the latter is more straightforward but the problem is that it entails that some observations need to be corrected. The former may be more awkward but it has the advantage that “the observer is always right.” This accords with a common-sense realism and empiricism.
Consider optical illusions. They are something that appears one way but under further investigation are another way, such as the horizontal lines in this cafe wall illusion that appear to be sloped:
But what about refraction? When we see a stick in water, it appears to bend but when we put our hand in the water, there is no bend. Yet we do not call this an illusion. We call it refraction. That is, it is an optical phenomenon and the appearance of a bend is real.
So it is a matter of classification. Yet all classifications are a matter of convention. We cannot get away from convention. In that sense reality is ambiguous or (à la Heisenberg) uncertain.
Since Plato and Aristotle science has included an attempt to “save the phenomena”. Although they meant different things by this phrase, it does indicate the primacy of phenomena. After all, there is no science (except perhaps for mathematics) without appearances. If all appearances are illusory, then appearance is not something to be explained but to be explained away.
A common-sense realist takes appearance as reality, with the understanding that some reflection is needed to avoid mistakes.
The knowledge the realist is talking about is the lived and experienced unity of an intellect with an apprehended reality. This is why a realist philosophy has to do with the thing itself that is apprehended, and without which there would be no knowledge. (#5 in A Handbook for Beginning Realists by Étienne Gilson)
Properly apprehended, the world of appearances is the real world. The observer is always right.