So coming back to the theme of today's session.
We saw in Galileo the poignant example of someone that believed that the aim of
signs was not just to save the appearances.
But to provide us with a true story about the world.
Now this view is known in the philosophy sense literature as scientific realism.
Scientific realism says that the aim of science is to provide us with
theories which literally construed we believe to be true.
There are two different aspects in this definition.
The first is a semantic aspect.
It has to do with the language of science,
the language in which our theories are formulated.
And it basically says that we should take the language of science at face value.
So if we have a theory, say Copernican astronomy that talks about planets,
we should understand the term planet as referring as picking
out objects in the external world.
Say for any other theoretical terms, if we have a theory of an electron, we should
understand the term electron as referring, spitting out electrons in the world.
Then there's a separate aspect, which is an epistemic aspect.
And that says that whenever we accept a scientific theory,
we believe that the theory is true or at least approximately true.
In other words, whatever the theory says about those objects, be they planets or
electrons, correspond to facts in the external world.
Now, appealing and intuitive as this may sound, as we have just seen with Ptolemy,
and Simplicius and Luciander this was not the way in which, for
many centuries, science was conceived.
So we need the proper philosophical argument for scientific realism, and
the argument is known as the No Miracles Argument.
So in the original formulation of Hilary Putnam,
the No Miracles Argument says that scientific realism
is the only philosophy that does not make the success of science a miracle.
The terms were fair.
The theories are approximately true that the same term
can refer to the same objects even if it occurs in different scientific theories.
These statements are the only explanation of the incredible success of our science.
So a natural account of how science grows and unfolds, say of the way which
Newtonian mechanics replaced Aristotelian physics or Copernican astronomy replaced
Ptolemaic astronomy or Einstein relativity theory replaced Newtonian mechanics.
Is that partially correct partially incorrect account
of a given object is replaced by a better account of the same object.
But the No Miracle Argument says, if those objects don't exist, if our theories were
not really true or at least approximately true of the same objects, then it would be
just a miracle that we have a theory like Newtonian mechanics that
talks about gravitational attraction and is so successful in predicting phenomena.
If curved space time didn't exist,
then it would be just a miracle that a theory like Einstein relativity proves so
successful again in predicting phenomena like the Perihelion of Mercury and so on.
In other words, one must be a scientific realist in order to explain
the incredible success of our science across centuries.