Saving the Date vs.
Coherence
Reflections on fossils and
scientific method
Saving the Data
• When Copernicus’ proposal that the
planets all orbit the sun was put forward a
narrow interpretation of his system was
proposed:
• That all his account was meant to do was
to fit the data, that is, to correctly predict
the motions of the planets through the
night sky.
Galileo
• It was Galileo’s insistence that the Copernican
theory was literally true that led to his encounter
with the inquisition and his subsequent
imprisonment.
• So we have a long history of two very different
attitudes towards scientific theories: according
to some, all that they are meant to do is to fit the
observable facts; according to others, though,
scientific theories actually aim to tell us the truth
about how things are in the world.
Upshot
• Of course in the case of Copernicanism, we’ve
become convinced in the meanwhile that
Copernicus was really right– that the planets do
move around the sun, and not around the earth,
as Ptolemaic astronomy held.
• But today only Copernicanism and its successor,
Classical (Newtonian) physics really fits all the
observable data concerning the planets’
motions. (In fact, some of the data requires
refinements to Classical physics found in
Einstein’s theory of general relativity.)
So the question remains:
• Which view of science is right?
• Does science just aim to ‘save the data’?
• Or does science aim to describe the world
as it truly is?
A Different Question
• What are the data that we need to ‘save’?
• Is saving the data (fitting all of our
observations into the scientific ‘picture’ of
things) really all that we ask of a theory?
• Is saving the data the same thing as
coherence, such as the coherence
between claims about processes and
traces that underwrites knowledge of the
past?
An unkind example
• If the data really are just the presently
observable facts, then the 5-minute
hypothesis fits the data just fine.
• But no scientist would take that hypothesis
seriously as a scientific proposal!
• Why not? After all, by hypothesis, it does
save the data!
• What’s wrong with the 5-minute
hypothesis?
Coherence
• Fitting the data is part of what coherence
demands. If we have data, i.e. claims that
are well-established by observation, any
correct theory has got to be compatible
with them.
• But coherence has a more positive side:
to be coherent, a theory needs to do more
than fit the data.
What more?
• It must explain at least some aspects of the
data– that is, it must provide enough information
about the circumstances that we can infer (some
of) what we observe from other things that we
observe.
• It must make predictions about other data we
might observe. (This is pretty well guaranteed
give the explanatory requirement.)
• Some of these predictions must be observed to
be correct. (This sort of successful application
of a theory is sometimes called vindication.)
Consider Fossils
Does the standard view of fossils
have coherence?
• We have explanations of many features (the
bias towards fossils of hard parts, the kinds of
rock where fossils of various kinds are found,
etc.)
• We also have applications (we can make
predictions about what sorts of fossils should be
found in what rock formations) that have
succeeded, i.e. we have vindication.
• So the answer is, yes, indeed– and increasingly
so, over the course of history since Steno and
Hooke.
How does the 5-minute Hypothesis
deal with fossils?
• It says that the world as we now observe it
is just as if it was the result of a long
history of geological and biological
processes, with all the ‘traces’ such
processes would leave.
• But they aren’t traces of processes that
really happened. They are ‘as if’ traces of
processes that never happened.
The Coherence of the 5-minute
hypothesis
• Whether we think the 5-minute hypothesis meets our
conditions for coherence depends on how we think of it:
• We can think of it as including the entire normal scientific
story, all under the dismissive qualification that things are
‘as if’ all this were true.
• Then it is just as coherent and just as testable as the
normal scientific story.
• But it’s also hard to tell the difference between the two:
Just what does adding ‘it’s as if’ to the front of everything
scientists say really do? Does this ‘it’s as if’ really mean
anything at all?
Parasitic Theories
• A parasitic theory is a theory that uses a different,
underlying theory to ‘do all the work’, and then (pretends
to) reject that theory and present an alternative to it.
• But if all the work is done by the underlying theory, then
we have to ask why we should take the ‘success’ of the
parasitic theory as a reason to take it, instead of the
underlying theory, seriously.
• For scientific purposes, the parasitic version of the 5
minute hypothesis is indistinguishable from the standard
view. The phrase, ‘it’s as if,’ adds nothing at all and so
(we might argue) should not be regarded as meaningful
at all. (Only a kind of ‘conceptual momentum,’ deriving
from its standard use in cases where it really makes a
difference, leads it to seem at all significant here…)