To explain the NATURAL WORLD and how
it got to be the way it is.
 NOT merely to collect “facts” or
describe.
 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
BIOLOGICAL LIMITATIONS OF OUR
SENSES.
› 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
explanation.
 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
INTERPRETED.

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
ideal.
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
truth.”


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
COMPARATIVE CRITICAL THINKING to
determine which explanation is MORE
LIKELY TO BE CORRECT.

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
processes;
 accounts for more data;
 has fewer unexplained exceptions;
 has more reliable predictive power;
 accounts for previously unexplained
phenomena;
 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.
