To explain the NATURAL WORLD and how
it got to be the way it is.
 NOT merely to collect “facts” or
 Natural here means empirically
sensible—that which we can detect with
our senses and for which there is
widespread agreement.
* An empirical explanation entails
detailed, precise explanations and
possesses predictive power.
Limited to the natural world
 Inherently uncertain to varying degrees
 i.e., it is NOT absolutely, eternally, and
infallibly TRUE.
 This built-in uncertainty is due in part to
the following assumptions:
The physical universe is real and exists
apart from our sensory perception of it.
 Humans are capable of accurately
perceiving the physical universe and
understanding how it operates
 Natural processes are SUFFICIENT to
explain or account for natural
phenomena and events.
Nature operates UNIFORMLY in space
and time (see: Lyell)
Scientific knowledge, (since it is based
on human sensory experience of the
natural world) is subject to the
› While technology has greatly extended the
range of our senses (think of UV and infra-red
light etc.) There are still limits to
technological accuracy and range.
It is impossible to know if we have
thought of every possible alternative
 It is probably always impossible to control
for every possible variable.
For two reasons:
› 1. Scientific knowledge is evidence-based.
Scientific Knowledge (including scientific
explanations) is based only on available
evidence, rather than on “proof” (which is
indisputable and irrefutable).
› 2. That evidence must be EVALUATED and
2. Scientific knowledge is historical.
The history of scientific knowledge is subject to
modification in light of new evidence.
 The questions and problems that scientists regard
as interesting and important at any given time
are reflective of intellectual, cultural and political
considerations that change over time.
despite this uncertainty and tentativeness,
scientific knowledge (and to a lesser
extent, scientific “facts”) constitute the
most reliable knowledge we can have
about the natural world and how it
works. Why?
This is because of CRITICAL THINKING
Assumptions and current knowledge
(even “facts”) are subject to regular
review and re-assessment—especially in
light of new evidence.
Independent duplication of results is
Concordant evidence is sought as
support for an explanation.
 Scientific knowledge is (ideally) available
for public knowledge.
 Expertise in knowledge is highly
regarded, but there is no reliance on any
absolute authority to determine “the
So, like, any explanation is equally, like,
valid—right? And truth is just a matter of
opinion, and like, we can’t even say
who’s right.
In the absence of certainty regarding
the absolute truth of scientific
explanations, scientists use
determine which explanation is MORE
A scientific explanation (which is limited
in all the ways we’ve already discussed)
is considered better than another the
more it…
is consistent with known natural
 accounts for more data;
 has fewer unexplained exceptions;
 has more reliable predictive power;
 accounts for previously unexplained
 is simpler;
 provides a fertile field for future research.
We can see the history of science as a
record of our scientific efforts to reduce
the degree of uncertainty associated
with our knowledge of the natural world.
 Thus, science can be said to “progress,”
but only in the negative sense of
eliminating faulty explanations, and
increasing our confidence in some
specific scientific knowledge, and in
science in general.