But if that's so, should we really believe in the scientific realism as the best
explanation of the success of signs? Not so fast again theorist would reply.
Now, scientific anti-realism is a house with many mansions.
And a prominent variety in the modern philosophy of science is the variety known
as constructive empiricism, which has been elaborated by the American philosopher,
Bas Van Fraassen since the early 1980s. A distinctive aspect of constructive
empiricism is that it agrees with scientific queries about the semantic
aspect. Namely, constructive empiricists would
agree with the scientific queries that we should take the language of science at
face value, that we should understand the main theoretical theorems such as planet
or electrons or whatever, as referring to objects in the external world.
But, the constructive empiricist would disagree with the realism about epistemic
aspect. In other words, the constructive
empiricist would claim that we don't need to believe the theories to be true for
them to be good. Now, the name constructive empiricism
stresses that there's an important element of construction that goes on in scientific
activity, especially in the way we build a scientific models, which are meant to be
adequate to the phenomenon. And the word empiricism emphasizes that
this is ultimately an empiricist position in believing that our knowledge should be
confined with the available experimental evidence as opposed to going beyond the
available evidence and claiming to discover truth about the unobservable.
So, what is the unobservable? And what does it mean that we construct
models that are adequate to the phenomena, but they don't necessarily tell us the
truth about the unobservables. Consider minerals.
There are some observable phenomena that we can study about minerals.
For example, their melting points, their hardness, how easily they may combine with
each other. But there are other aspects which are
strictly speaking unobservable to the human eye.
For example, chemistry classifies gold as the metal with atomic number 79.
And the atomic number is defining terms of number of protons and electrons
distinctive of the element. So strictly speaking, whereas we can
observe with our naked eye the property of melting point, the hardness and so forth,
we can't observe with our naked eye the atomic number or the molecular composition
of minerals. But we do construct models of them.
Indeed, we do construct them formal models, like these crystal models and
minerals, for example. Which allows me to represent the molecular
composition. Using both the different colors, arranged
according to some dramatic structure, that is meant to be adequate to the phenomena.
For example, that is meant to represent how easily we can slice the minerals along
some of these chemical bonds. Yet the constructive empiricists would
insist we shouldn't take models as providing the truth about the
unobservable, namely about atoms, molecules or chemical arrangements.
Models must only be adequate to the observable phenomena.
They are useful tools to get calculations done, but they don't deliver any truth
about the unobservable entities. So, constructive imperialism would insist
that scientific theory is not to be true to be in order to be good, they only need
to be empirically adequate. And a theory is empirically adequate if
whatever the theory says about things observable and in events in the world, the
past, the present and future is true. In other words, the theories empirically
adequate if the theory saves the phenomena.
In this way, empirical adequacy rather than a truth becomes the aim of science.
Now, this conclusion chimes, in many ways, with the old view of ancient Greek
astronomy, that the aim of the science was to save the phenomena.
But there are some important differences. For ancient Greek astronomy, the aim was
to save the phenomena. Because Ptolemy, and Simplicious, and so
forth, so that human knowledge cannot vie with divine knowledge.
But after Galileo, that view could no longer be maintained.
So, for more than signs, the reason why some anti-realists may want to insist that
the aim is not truth but empirical adequacy has nothing to do with the
distinction between human knowledge and divine knowledge.
And a lot to do with the metaphysical commitment that theories bring along with
them, on one hand, and on the other hand, with the idealized and abstract nature of
the scientific models that we build. As far as the latter is concerned, in the
past 30 years or so, an increase in literature in the philosophy of science
has stressed how abstraction and idealization enter into the construction
of models. So that although the models are very
useful in explanatory tools in everyday practice, they will not necessarily be
true of states of affairs in the world. If not in a very idealized sense, or in
very idealized circumstances. For example, in this double helix stick
and ball model of the DNA sequence, we need to abstract from the terribly
complicated cellular environment in which DNA sequences can be found in nature.
And we also need to idealize the atoms involved as, preferably speckled balls of
different colors, as well as we need to idealize the direction of the helix
spiral, right-handed or left-handed, to represent the different forms of the dna
molecules. So, models can be very useful and
informative and explanatory, even if we don't have to think of them as providing a
perfectly true picture of the target system.
As far as metaphysical commitment is concerned, the constructive empiricist
will insist that she can do exactly the same good quality science as the
scientific realist. In other words, one again doesn't need to
believe that theories true to explain why we have such a successful signs.
One can just say that the success of our present theories is the result of a
struggle for survival across centuries. So, the best theories in mature science
are the ones that have proved survival adaptive, are the ones that have proved to
save the available evidence, without necessarily being true.
So, in reply to the [unknown] argument, the constructive empiricist would insist
that we can give an explanation, some sort of the Darwinian explanation, of why
science is so successful by appealing to empirical adequacy rather than truth.
Moreover, the constructive empiricist would insist that scientific realism is
some sort of high risk strategy when it comes to metaphysical commitment.
What if the unobservable entities that we take to be true in the present signs turn
out to be like unobservable entities that people in the past believed to be true and
they proved to non-existent? What if, in 100 years time, our electrons
and neutrinos, and protons and DNA turn out to be like the ether, or the
phlogiston or the caloric, or all those other unobservable entities that people in
the past believed and that are now just a remnant of a discarded past.