Transcript ppt - Furman University

I. What is Science?
A. Definition:
Webster’s: “systematized knowledge derived
from observation, study, and experimentation
carried on in order to determine the nature or
principles of what is being studied. The
systematized knowledge of nature and the
physical world.”
I. What is Science?
A. Definition:
Webster’s: “systematized knowledge derived
from observation, study, and experimentation
carried on in order to determine the nature or
principles of what is being studied. The
systematized knowledge of nature and the
physical world.”
I. What is Science?
B. Limitations:
- What is studied: the physical world /universe
A medieval, Ptolemeic
view of the universe
I. What is Science?
B. Limitations:
- What is studied: the physical world /universe
- How it is studied (Method): empiricism
“of the senses”, but not “common sense”…
-Methodological Approaches:
1. REDUCTIONISM
Gaining an understanding of a system by
describing its subsystems (components)
-Methodological Approaches:
1. REDUCTIONISM
Gaining an understanding of a system by
describing its subsystems (components)
≠
“emergent properties”
Powerful Approach: living systems are very complex, so
describing the STRUCTURE can give insights into FUNCTION.
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
The function of complex systems may be understood by
comparing them with simpler systems (with fewer
subsystems).
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
The function of complex systems may be understood by
comparing them with simpler systems (with fewer
subsystems).
How could a complex system like a
camera eye, composed of mutually
dependent parts, have evolved
through a stepwise sequence?
Half an eye (lens) can’t work…
2. COMPARATIVE METHOD
The function of complex systems may be understood by
comparing them with simpler systems (with fewer
subsystems). Visual systems in molluscs:
Half an eye
(retina) CAN
work…
2. COMPARATIVE METHOD
Why is this method so powerful in biology? Is there a
REASON why different organisms might have similar
structures and functions?
2. COMPARATIVE METHOD
Why is this method so powerful in biology? Is there a
REASON why different organisms might have similar
structures and functions? Yes… common ancestry.
This is why the use of model organisms (E. coli, fruit fly,
house mouse) illuminates the field of medicine
And the most dramatic
examples of homology
are in the hox genes, as
well.
In fact, the homology is
so good that lineages of
eyeless flies lacking that
hox gene can have the
ability to grow eyes
restored by adding the
homologous gene from a
mouse…and flies
develop compound eyes
with the mouse hox gene
for eye development,
even though mice have
camera eyes…
HOW COOL IS
THAT!?
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
3. EXPERIMENTATION (EMPIRICISM)
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
3. EXPERIMENTATION (EMPIRICISM)
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, there are no spiders”
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, spiders are rare”
GOAL: is this relationship causal?
Bring other observed facts to bear
“They use similar habitats” (could live together)
“Lizards eat spiders”
“Lizards and spiders eat other insects”
“They disperse differently” (so they may have gotten to
different islands by chance)
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, spiders are rare”
GOAL: create GOAL:
a falsifiable
is this
(testable)
relationship
causal
causal
hypothesis
?
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, spiders are rare”
GOAL: create GOAL:
a falsifiable
is this
(testable)
relationship
causal
causal
hypothesis
?
Bring other observed facts to bear
“They use similar habitats” (could live together)
“Lizards eat spiders”
“Lizards and spiders eat other insects”
“They disperse differently” (so they may have gotten to
different islands by chance)
“Hawks eat lizards but not spiders, so maybe it just happens
that hawks and spiders are together”
“Some warblers eat spiders and not lizards, and maybe it just
happens that warblers and lizards are together”
“Lizards run around and may break spider webs and starve
them inadvertently”
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, spiders are rare”
GOAL: create a falsifiable (testable) causal hypothesis
Bring other observed facts to bear
“They use similar habitats” (could live together)
“Lizards eat spiders”
“Lizards and spiders eat other insects”
“They disperse differently” (so they may have gotten to
different islands by chance)
“Hawks eat lizards but not spiders, so maybe it just happens
that hawks and spiders are together”
“Some warblers eat spiders and not lizards, and maybe it just
happens that warblers and lizards are together”
“Lizards run around and may break spider webs and starve
them inadvertently”
You can envision many alternative causal hypotheses …and there are
nearly a limitless supply…you can’t test them all (so scientific facts aren’t
eternal truths or PROOFS)… test the simplest explanation first = “principle
of parsimony” or “Occam’s razor”
Bring other observed facts to bear
“They use similar habitats” (could live together)
“Lizards eat spiders”
“Lizards and spiders eat other insects”
“They disperse differently” (so they may have gotten to
different islands by chance)
“Hawks eat lizards but not spiders, so maybe it just happens
that hawks and spiders are together”
“Some warblers eat spiders and not lizards, and maybe it just
happens that warblers and lizards are together”
“Lizards run around and may break spider webs and starve
them inadvertently”
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, spiders are rare”
GOAL: create GOAL:
a falsifiable
is this
(testable)
relationship
causal
causal
hypothesis
?
Other observations
Hypothesis: Lizard predation causes a reduction in spider
abundance on Caribbean Islands
You have just used Inductive logic , using specific
observations to formulate a general principle
Observe repeated, correlated physical phenomena/patterns
“On Caribbean Islands with lizards, spiders are rare”
GOAL: create GOAL:
a falsifiable
is this
(testable)
relationship
causal
causal
hypothesis
?
Other observations
Hypothesis: Lizard predation causes a reduction in spider
abundance on Caribbean Islands.
Alternative Hypothesis: Lizard predation does not cause a
reduction in spider abundance… (maybe competition does
or maybe it is just a correlated effect of something else…)
Here is a another critical element of a scientific hypothesis – it must be
falsifiable – you must be able to envision data collected from the
physical universe that would prove your hypothesis is wrong.
Hypothesis: Lizard predation causes a reduction in spider
abundance on Caribbean Islands
Alternative Hypothesis: Lizard predation does not cause a
reduction in spider abundance… (maybe competition does
or maybe it is just a correlated effect of something else…)
Conduct an experiment in which data supporting either
hypothesis is possible.
To do this, you use deductive logic (general to specific case).
IF my general principle (hypothesis) is true, THEN I can predict
a specific outcome in my particular experiment.
IF: - lizard predation is responsible for low spider abundance
And
IF: - I add lizards to specific islands and remove lizards from
others, with appropriate controls for the manipulations,
THEN: - Spider abundance should decline where I add lizards
and increase where I remove lizards, and spiders should be a
major component of lizard diets (gut content analysis).
IF: - lizard predation is responsible for low spider abundance
And
IF: - I add lizards to specific islands and remove lizards from
others, with appropriate controls for the manipulations,
THEN: - Spider abundance should decline where I add lizards
and increase where I remove lizards, and spiders should be a
major component of lizard diets (gut content analysis).
Then you do it and see!!! And you generalize from your
specific experiment to nature (inductive logic). You use logic
and evidence from the physical world to reach a conclusion
about how nature is and how it works.
(Usually by statistical inference…)
Then you do it and see!!! And you generalize from your
specific experiment to nature (inductive logic). You use logic
and evidence from the physical world to reach a conclusion
about how nature is and how it works.
Many lines of independent evidence…
Then you do it and see!!! And you generalize from your
specific experiment to nature (inductive logic). You use logic
and evidence from the physical world to reach a conclusion
about how nature is and how it works.
Many lines of independent evidence…
can support a single general explanation
Then you do it and see!!! And you generalize from your
specific experiment to nature (inductive logic). You use logic
and evidence from the physical world to reach a conclusion
about how nature is and how it works.
Many lines of independent evidence…
can support a single general explanation…
These Explanations are THEORIES. They are supported by
experimental results and they can be tested by subsequent experiments
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
3. EXPERIMENTATION (EMPIRICISM)
4. METHODOLOGICAL MATERIALISM
-Methodological Approaches:
1. REDUCTIONISM
2. COMPARATIVE METHOD
3. EXPERIMENTATION (EMPIRICISM)
4. METHODOLOGICAL MATERIALISM
Philosophical materialism – the material is all there is.
Methodological materialism – the material is all we can
test.
I. What is Science?
A. Definitions
B. Limitations
C. Theories
- tested, explanatory models of how the
physical universe works
I. What is Science?
A. Definitions
B. Limitations
C. Theories
- tested, explanatory models of how the
physical universe works
II. Context: Ways of Knowing
A. Why You Know - Searching for Truth
1. Faith: Webster’s – “unquestioning belief not
requiring proof or evidence”
II. Context: Ways of Knowing
A. Why You Know - Searching for Truth
1. Faith: Webster’s – “unquestioning belief not
requiring proof or evidence”
2. Logic: “the science of correct reasoning;
science which describes relationships among
propositions in terms of implication,
contradiction, contrariety, conversion, etc.”
Evidence is a "clean argument“, but it does not
have to describe a physical reality.
II. Context: Ways of Knowing
A. Why You Know - Searching for Truth
1. Faith: Webster’s – “unquestioning belief not
requiring proof or evidence”
2. Logic: “the science of correct reasoning;
science which describes relationships among
propositions in terms of implication,
contradiction, contrariety, conversion, etc.”
Evidence is a "clean argument“
3. Science: Logical argument and physical
evidence.
II. Context: Ways of Knowing
A. Why You Know - Searching for Truth
B. Different Problems, Different Tools
“If the only tool you have is a hammer, you tend to
see every problem as a nail.”
– Abraham Maslow, American Psychologist
Is abortion right?
How old is the Earth?