QUEEN’S UNIVERSITY
DEPARTMENT OF PHILOSOPHY
WELCOME TO
PHL 381* PHILOSOPHY OF THE
NATURAL SCIENCES
Professor Joshua Mozersky
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Administrative matters
1. Syllabus
2. Classroom respect policy
3. Late policy
Tips for doing well in this course:
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Read each week’s material before class
Attend class regularly
Participate
Read each essay carefully—preferably
more than once
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Philosophy
Four branches of philosophy
Logic: The study of reasoning.
Ethics and value theory: The study of moral
and aesthetic claims.
Metaphysics (Ontology): The study the
most general features of reality.
Epistemology: The study of knowledge.
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Philosophy and science
Many of the most famous philosophers were
scientists or mathematicians:
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Aristotle (biology, medicine, cosmology)
Descartes (geometry)
Leibniz (calculus)
Kant (physics, geography)
Russell (mathematical logic)
So science and philosophy have a deep
connection. Here is at least one reason
why:
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Science, knowledge and reality
Science has two features of interest to the
philosopher:
1. It seems to be the best means of
securing knowledge.
2. Its theories seem to tell us what the
world is like.
So, understanding science can help us to
understand the nature of knowledge and
reality.
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What is science?
We are interested in:
1. Understanding the nature of science
2. Examining the impact of science on
traditional philosophical questions
So, we begin the course by asking:
What distinguishes science from nonscience?
 This is a question about the methods of
science rather than the answers it gives.
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Epistemology primer
What is it to know that P? Here is the
traditional answer:
S knows that P if and only if:
1. S believes that P
2. P is true
3. S’s belief that P is justified (S has
adequate reason to believe that P)
A key question for epistemology: how are
beliefs justified?
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Two traditions
Rationalism
 Knowledge is derived from (justified by)
reason not the senses.
 The senses may provide information for
reason to use but they cannot provide
knowledge themselves.
 E.g.: Descartes, Leibniz, and Spinoza.
Empiricism
 These senses are the source
(justification) of all knowledge.
 Everything we know is either observed
directly or else deduced on the basis of
observation.
 E.g. Locke, Berkeley, Hume.
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Rationalism
Rationalism may seem implausible, but
consider Descartes’ example:
 I observe a piece of wax. It is solid,
cold, scented, white.
 I approach the fire. The wax is now
liquid, warm, scentless, clear.
Every sensory property has changed!
Descartes: So, if I know it is one and the
same wax before and after, this knowledge
cannot be delivered by the senses.
 Even empirical knowledge is the result
of reason.
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Rationalism and metaphysics
Traditionally, rationalism has been more
amenable to metaphysical speculation:
 If reason is our source of knowledge,
then we can discover the nature of
reality by examining the nature of
reason.
But it is hard to see how reason alone can
answer these questions unless one
postulates a very intimate connection
between the human mind and non-mental
reality.
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Metaphysical systems
There are a number of possibilities here:
Solipsism: there is no reality outside the
mind.
Idealism: all reality is made up of ideas.
There are things outside the mind, but
they are just ideas in the mind of God.
Kantianism: the mind constitutes external
reality—what is real depends on the
human mind’s activities.
Cartesian rationalism: I can be certain that
God exists and that God doesn’t
deceive me so I can be confident that
my thoughts are accurate.
These systems are designed to justify the
use of reason as the source of knowledge.
 They often involve supernatural or
theological elements.
But a number of scientific developments
cast doubt on these approaches…
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First example: geometry
Kant was very influential. He argued that
the mind imposes categories on reality that
are universal and necessary.
These categories include Newtonian space
and time—i.e. a physics that is governed by
Euclidean geometry.
But, in the 19th Century, non-Euclidean
geometries were developed. They were:
 Coherent
 Scientifically useful (Einstein)
So the idea of universal mental categories
that determine reality seemed implausible—
our experience can be misleading.
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Second example: Darwin
Darwin’s theory of natural selection showed
that through chance physical processes:
 Some traits will multiply over time
 Others will be eliminated
 Result: a system of creatures very well
designed for their environment.
This process was not ‘purposeful’ or
‘directed’ by God; it was simply a
combination of chance and causation.
Most scientists saw Darwinian (causal)
explanation as superior to traditional
metaphysical explanations, e.g. God.
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Third Example: Hans Driesch
He is a renowned embryologist.
His experiments: The development of an
embryo proceeds normally even if:
 The early cells are rearranged
 A single early cell is isolated
His conclusion: Neither spatiotemporal
location nor physical mass is relevant to the
development of the embryo.
His explanation: There exists a non-physical
organizing principle—an entelechy—that
guides the development of living things.
Entelechies impinge on the spatiotemporal
world, but have no quantitative features so
they can’t be measured. They can only be
known by reflection on empirical results.
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Science vs. non-science
Philosophers came to think that postulations
such as entelechies were ‘occult’ entities
that had no place in science.
 Explanations should be more like
Darwin’s.
They already had some idea as to what
counted as science and what didn’t:
Science
Physics
Biology
Chemistry
Astronomy
Etc.
Non-science
Theology
Entelechy
Alchemy
Astrology
Etc.
Still, it would be nice if we could determine a
principle that captures what is distinctive
about science…
Stay tuned, more is coming next week!
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