The document describes the scientific method and key aspects of scientific thinking. It discusses how science involves making objective observations and testing hypotheses through experimentation. The scientific method includes forming a hypothesis to explain observations, making testable predictions, conducting experiments to test predictions, and revising hypotheses based on results. Controlled experiments and minimizing biases are important for producing reliable results. Scientific theories emerge when hypotheses are strongly supported by evidence over time.

1. Scientific ThinkingScientific Thinking
BIOLBIOL 108 Intro to Bio108 Intro to Bio SciSci
Chapter 1Chapter 1
RobRob SwatskiSwatski
Assoc Prof BiologyAssoc Prof Biology
HACCHACC--YorkYork
1

2. Learning GoalsLearning GoalsLearning GoalsLearning Goals
Describe
what science
is.
Describe the
scientific
method.
Describe the
key aspects
of well-
designed
experiments.
Describe how
the scientific
method can
be used to
help make
wise
decisions.
Describe the
major
themes in
biology.
2

3. 1.11.1
WhatWhat is science?is science?
WhatWhat is biology?is biology?
3

4. 4

5. ScientistsScientistsScientistsScientists
Are curious
Ask questions
about how the
world works
Seek answers
5

6. Science is NOT simply a body ofScience is NOT simply a body of
knowledge or a list of facts toknowledge or a list of facts to
bebe remembered…remembered…6

7. Science is an intellectual activity,Science is an intellectual activity,
encompassing observation, description,encompassing observation, description,
experimentation, and explanation ofexperimentation, and explanation of
natural phenomena.natural phenomena.
7

8. “How do you know that is true?”“How do you know that is true?”
The single question that underlies
scientific thinking 8

9. Can we trust the packaging claims thatCan we trust the packaging claims that
companies make?companies make?
9

10. Don’t be at the mercy of cranks,Don’t be at the mercy of cranks,
charlatans, advertising, or slickcharlatans, advertising, or slick
packagingpackaging
Learn exactly what it
means to have
scientific proof or
evidence
Learn what it means
to think scientifically
10

11. The mostThe most
importantimportant
questions inquestions in
biology:biology:
The mostThe most
importantimportant
questions inquestions in
biology:biology:
What is the chemical and
physical basis for life and
its maintenance?
What is the chemical and
physical basis for life and
its maintenance?
How do organisms use
genetic information to
build themselves and to
reproduce?
How do organisms use
genetic information to
build themselves and to
reproduce?
What are the diverse
forms that life on Earth
takes and how has that
diversity arisen?
What are the diverse
forms that life on Earth
takes and how has that
diversity arisen?
How do organisms interact
with each other and with
their environment?
How do organisms interact
with each other and with
their environment?
11

12. How to think
scientifically
Increasingly
important in our
lives
How to use the
knowledge we
gain to make wise
decisions
Literacy in matters
of biology is
especially essential
Scientific LiteracyScientific Literacy
12

13. TakeTake--Home Message 1.1Home Message 1.1
Through its emphasis on
objective observation,
description, and
experimentation, science is a
pathway by which we can come
to discover and better
understand the world around us.
Through its emphasis on
objective observation,
description, and
experimentation, science is a
pathway by which we can come
to discover and better
understand the world around us.
13

14. 1.2 Biological literacy is essential in
the modern world.
14

15. Biological LiteracyBiological LiteracyBiological LiteracyBiological Literacy
Use the
process of
scientific
inquiry to
think
creatively
about real-
world issues
Communicate
those
thoughts to
others
Integrate them
into your
decision-
making
15

16. “Scientific issues permeate the law. I believe
[that] in this age of science we must build
legal foundations that are sound in science
as well as in law. The result, in my view,
will further not only the interests of truth
but also those of justice.”
U.S. Supreme Court Justice Stephen Breyer
February 1998 at the annual meeting of the
American Association for the Advancement of Science
16

17. TakeTake--Home Message 1.2Home Message 1.2
Biological issues
permeate all aspects of
our lives.
To make wise decisions,
it is essential for
individuals and societies
to attain biological
literacy.
17

18. The Culture of Science:The Culture of Science: CreativityCreativity 18
1.3 The scientific method is a
powerful approach to
understanding the world.

19. Why and whenWhy and when
do peopledo people
developdevelop
superstitions &superstitions &
belief in thebelief in the
paranormal?paranormal?
19

20. 20

21. 21

22. The ScientificThe Scientific
MethodMethod
The ScientificThe Scientific
MethodMethod
An empirical process
of examination &
discovery
Based on experience
& observations that
are rational, testable,
& repeatable
22

23. The Scientific MethodThe Scientific Method
Observe a
phenomenon
Propose an
explanation for it
Test the proposed
explanation through a
series of experiments
Explanation is
accurate & valid
Revise or propose
alternative
explanations
23

24. TakeTake--Home Message 1.3Home Message 1.3
There are numerous ways of
gaining an understanding of
the world.
Because it is empirical,
rational, testable,
repeatable, and self-
correcting, the scientific
method is a particularly
effective approach.
24

25. 25

26. 1.4 Thinking like a scientist:1.4 Thinking like a scientist:
how to use the scientifichow to use the scientific
methodmethod26

27. What is the ScientificWhat is the Scientific
Method?Method?
What is the ScientificWhat is the Scientific
Method?Method?
A rigid
process
to follow?
A recipe?
An
adaptable
process?
One that
includes
many
different
methods?
27

28. 1. Make Observations
2. Formulate a hypothesis
3. Devise a testable prediction
4. Conduct a critical experiment
5. Draw conclusions and make revisions
28

29. 29

30. What should you do whenWhat should you do when
something you believe in turnssomething you believe in turns
out to be wrong?out to be wrong?
This may be the most important feature of the
scientific method:
it tells us when we should change our minds.
30

31. Does echinacea reduce the intensity
or duration of the common cold?
Does chemical runoff give rise to
hermaphrodite fish?
Does shaving hair from your face, legs,
or anywhere else cause it to grow back
coarser or darker?
31

32. TakeTake--Home Message 1.4Home Message 1.4
The scientific method
(observation, hypothesis,
prediction, test, and conclusion) is
a flexible, adaptable, and efficient
pathway to understanding the
world because it tells us when we
must change our beliefs.
32

33. 1.51.5 Step 1Step 1: Make observations.: Make observations.
Look for interesting
patterns or cause-and-
effect relationships.
33

34. Does takingDoes taking echinaceaechinacea reduce the intensity orreduce the intensity or
duration of the common cold?duration of the common cold?
34

35. TakeTake--Home Message 1.5Home Message 1.5
The scientific method
begins by making
observations about the
world, noting apparent
patterns or cause-and-effect
relationships.
35

36. 1.61.6 Step 2Step 2: Formulate a hypothesis.: Formulate a hypothesis.
A proposed
explanation for
observed phenomena
36

37. 37

38. 38
To be most useful, a hypothesisTo be most useful, a hypothesis
must accomplish two things:must accomplish two things:
It must clearly establish
mutually exclusive
alternative explanations
for a phenomenon
It must generate
testable predictions

39. 39

40. The Null HypothesisThe Null HypothesisThe Null HypothesisThe Null Hypothesis
A negative
statement
that
proposes
that there is
no
relationship
between
two factors
These
hypotheses
are equally
valid but are
easier to
disprove
An
alternative
hypothesis
It is
impossible
to prove a
hypothesis is
absolutely
and
permanently
true
40

41. 41
HypothesisHypothesisHypothesisHypothesis
Echinacea reduces the
duration and severity
of the symptoms of
the common cold.
NullNull
HypothesisHypothesis
NullNull
HypothesisHypothesis
Echinacea has no
effect on the duration
or severity of the
symptoms of the
common cold.

42. TakeTake--Home Message 1.6Home Message 1.6
A hypothesis is a
proposed explanation
for a phenomenon.
42

43. 1.71.7 Step 3Step 3: Devise a testable: Devise a testable
prediction.prediction.
Suggest that under
certain conditions we
will make certain
observations.
43

44. 44
PredictionsPredictionsPredictionsPredictions
Propose a situation that
will give a particular
outcome if your
hypothesis is true…
…but that will give a
different outcome if
your hypothesis is not
true.
Keep in mind any one
of several possible
explanations could be
true.

45. Hypothesis:
Echinacea reduces
the duration and
severity of the
symptoms of the
common cold.
45

46. 46
Hypothesis: Eyewitness
testimony is always accurate.
Prediction: If individuals have
witnessed a crime, then they
will correctly identify the
criminal regardless of whether
multiple suspects are presented
in a lineup one at a time or all at
the same time.

47. 47
Hypothesis: Estrogens in sewage
runoff turn fish into
hermaphrodites.
Prediction: If estrogens in sewage
runoff turn fish into
hermaphrodites, then exposing
fish to estrogens should cause
them to turn into hermaphrodites
more frequently than fish not
exposed to estrogens.

48. 48
Hypothesis: Hair that is shaved
grows back coarser and darker.
Prediction: If shaving leads to
coarser, darker hair growing
back, then if individuals shaved
one leg only, the hair that grows
on that leg should become
darker and coarser than the hair
growing on the other leg.

49. TakeTake--Home Message 1.7Home Message 1.7
For a hypothesis to be
useful, it must generate
a testable prediction.
49

50. 1.81.8 Step 4Step 4: Conduct a critical: Conduct a critical
experiment.experiment.
An experiment that
makes it possible to
decisively determine
whether a particular
hypothesis is correct
50

51. Hypothesis: Echinacea
reduces the duration and
severity of the symptoms of
the common cold.
51

52. 52

53. 53

54. 54

55. 55

56. 56
HypothesisHypothesisHypothesisHypothesis
Estrogens in
sewage runoff
turn fish into
hermaphrodites.
Critical
experiment
ideas?

57. 57
HypothesisHypothesisHypothesisHypothesis
Hair that is
shaved grows
back coarser and
darker.
Critical
experiment
ideas?

58. TakeTake--Home Message 1.8Home Message 1.8
A critical experiment is
one that makes it possible
to decisively determine
whether a particular
hypothesis is correct.
58

59. 1.9 Step 5: Draw conclusions, make1.9 Step 5: Draw conclusions, make
revisions.revisions.
Trial and error
59

60. The Role of ExperimentsThe Role of ExperimentsThe Role of ExperimentsThe Role of Experiments
It is important that
we attempt to
demonstrate that
our initial
hypothesis is not
supported by the
data.
If it is not, we might
then adjust our
hypothesis.
60

61. 61
MakingMaking
RevisionsRevisions
MakingMaking
RevisionsRevisions
Try to further
refine a
hypothesis
Make new and
more specific
testable
predictions

62. Hypothesis: Echinacea reduces the duration and severity of
the symptoms of the common cold.
62

63. TakeTake--Home Message 1.9Home Message 1.9
Experimental test
results can be used to
revise hypotheses and
explain the observable
world more accurately.
Scientific thinking helps
us to understand when
we should change our
minds.
63

64. 1.10 When do hypotheses1.10 When do hypotheses
become theories?become theories?
64
Two distinct levels of
understanding that
scientists use in describing
our knowledge about
natural phenomena

65. 65
HypothesisHypothesisHypothesisHypothesis
A proposed
explanation for a
phenomenon
A good
hypothesis leads
to testable
predictions

66. 66
TheoryTheoryTheoryTheory
A hypothesis for natural
phenomena that is
exceptionally well-
supported by the data.
A hypothesis that has
withstood the test of
time & has been
repeatedly tested
Is unlikely to be altered
by any new evidence

67. TakeTake--Home Message 1.10Home Message 1.10
Scientific theories do not
represent speculation or guesses
about the natural world.
Theories are hypotheses that
have been so strongly supported
by empirical observation that
the scientific community views
them as very unlikely to be
altered by new evidence.
67

68. 68

69. 1.11 Controlling variables makes1.11 Controlling variables makes
experiments more powerful.experiments more powerful.
69

70. Elements Common to MostElements Common to Most
ExperimentsExperiments
Elements Common to MostElements Common to Most
ExperimentsExperiments
1. Treatment
2.
Experimental
group
3. Control
group
4. Variables
70

71. 71
1. Treatment1. Treatment Any experimental
condition applied to
individuals

72. 72
2. Experimental group2. Experimental group A group of
individuals who are
exposed to a
particular treatment

73. 73
3. Control group3. Control group A group of
individuals who are
treated identically
to the experimental
group with one
exception: they are
not exposed to the
treatment

74. 74
4. Variables4. Variables Characteristics of
your experimental
system that are
subject to change

75. 75
ControllingControlling
VariablesVariables
ControllingControlling
VariablesVariables
The most important
feature of a good
experiment
The attempt to minimize
any differences between a
control group and an
experimental group other
than the treatment itself

76. 76

77. 77
The PlaceboThe Placebo
EffectEffect
The PlaceboThe Placebo
EffectEffect
The phenomenon in
which people respond
favorably to any
treatment
Highlights the need
for comparison of
treatment effects
with an appropriate
control group

78. 78
Clever HansClever Hans

79. Experimental DesignsExperimental Designs
BlindBlind
The experimental subjects
do not know which
treatment (if any) they are
receiving
DoubleDouble--blindblind
Neither the experimental
subjects nor the
experimenter knows which
treatment the subject is
receiving79

80. 80
RandomizedRandomized
The subjects are
randomly
assigned into
experimental and
control groups

81. TakeTake--Home Message 1.11Home Message 1.11
In experiments, it is
essential to hold
constant all those
variables we are not
interested in.
Control and
experimental groups
should vary only with
respect to the
treatment of interest.
Differences in them
can then be attributed
to the treatment.
81

82. 1.12 Repeatable experiments1.12 Repeatable experiments
increase our confidence.increase our confidence.
Can science be misleading?
How can we know?
82

83. 83

84. 84

85. DoDo megadosesmegadoses of vitamin Cof vitamin C
reduce cancer risk?reduce cancer risk?
An experiment must be
reproducible and repeatable.
85

86. TakeTake--Home Message 1.12Home Message 1.12
Experiments and their
outcomes must be
repeatable for their
conclusions to be valid
and widely accepted.
86

87. 1.13 We’ve got to watch out for1.13 We’ve got to watch out for
biases.biases.
Can scientists be sexist?
How would we know?
87

88. 88

89. TakeTake--Home Message 1.13Home Message 1.13
Biases can influence
our behavior, including
our collection and
interpretation of data.
With careful controls,
it is possible to
minimize such biases.
89

90. 1.14-1.17
Scientific thinking
can help us make
wise decisions.
90

91. 1.141.14 Visual displays of dataVisual displays of data
can help us understand andcan help us understand and
explain phenomena.explain phenomena.
91

92. 92

93. 93

94. VariablesVariables
 Independent Variables
– some measurable entity that is available at
the start of a process and whose value can be
changed as required.
 Dependent Variables
– created by the process being observed and
whose value cannot be controlled.
94

95. TakeTake--home message 1.14home message 1.14
 Visual displays of data, which condense
large amounts of information, can aid in
the presentation and exploration of the
data.
95

96. 1.15 Statistics can help us to make1.15 Statistics can help us to make
decisions.decisions.
96
A set of analytical & mathematical tools
designed to help researchers gain understanding
from the data they gather.

97.  Drawing
conclusions based
on limited
observations is
risky.
 Measuring a greater
number of people
will generally help us
draw more accurate
conclusions about
human height.
97

98. Making Wise DecisionsMaking Wise Decisions
About Concrete ThingsAbout Concrete Things
 Does having access to a textbook help a
student to perform better in a biology
class?
• Students who had access to a textbook scored
an average of 81% ± 8% on their exams…
• …while those who did not scored an average
of 76% ± 7%.
98

99. 99

100. 100
StatisticsStatisticsStatisticsStatistics
Can help us to identify
relationships (or the lack of
relationships) between
variables
Positive correlation: when
one variable increases, so
does the other
“Correlation is not
causation.”
Statistical analyses can help
us to organize & summarize

101. TakeTake--Home Message 1.15Home Message 1.15
Because much variation exists in
the world, statistics can help us
evaluate whether differences
between a treatment and
control group can be attributed
to the treatment rather than
random chance.
101

102. 1.161.16
Pseudoscience andPseudoscience and
misleadingmisleading
anecdotalanecdotal
evidence canevidence can
obscure the truth.obscure the truth.
102

103. 103
PseudosciencePseudosciencePseudosciencePseudoscience
Individuals make
scientific-sounding claims
that are not supported by
trustworthy, methodical
scientific studies
AnecdotalAnecdotal
observationsobservations
AnecdotalAnecdotal
observationsobservations
Based on only one or a
few observations, people
conclude that there is or
is not a link between two
things

104. “Four out of five dentists surveyed“Four out of five dentists surveyed
recommend sugarless gum for their patientsrecommend sugarless gum for their patients
who chew gum.”who chew gum.”
“How do they know what they know?”
Maybe the statement is factually true, but the
general relationship it implies may not be.
104

105. 105
AnecdotalAnecdotal
observationsobservations
AnecdotalAnecdotal
observationsobservations
Do not include a
sufficiently large and
representative set of
observations of the
world
Data are more reliable
than anecdotes

106. “Science is a way to call the bluff of those who
only pretend to knowledge. It is a bulwark
against mysticism, against superstition,
against religion misapplied to where it has no
business being. If we’re true to its values, it
can tell us when we’re being lied to.”
—Carl Sagan
106

107. TakeTake--Home Message 1.16Home Message 1.16
Pseudoscience and
anecdotal observations
often lead people to believe
that links between two
phenomena exist, when in
fact there are no such links.
107

108. 1.17 There are limits to what1.17 There are limits to what
science can do.science can do.
1.17 There are limits to what1.17 There are limits to what
science can do.science can do.
The scientific
method will
never prove
or disprove
the
existence of
God.
Understand
elegance?
What is
beauty?
108

109. 109
Approaches to the AcquisitionApproaches to the Acquisition
of Knowledgeof Knowledge
The scientific
method is, above
all, empirical
Value judgments
and subjective
information
Moral
statements and
ethical problems

110. TakeTake--Home Message 1.17Home Message 1.17
Although the scientific method may
be the most effective path toward
understanding the observable
world, it cannot give us insights into
the generation of value judgments
and other types of non-quantifiable,
subjective information.
110

111. 1.18
On the road to
biological
literacy: what are
the major themes
in biology?
111

112. 1.18 A few important themes tie1.18 A few important themes tie
together the diverse topics in biology.together the diverse topics in biology.
112
Hierarchical
organization
The power
of evolution

113. Four Chief Areas of FocusFour Chief Areas of Focus
1. The chemical, cellular, and energetic
foundations of life
2. The genetics, evolution, and behavior of
individuals
3. The staggering diversity of life and the unity
underlying it
4. Ecology, the environment, and the subtle
and important links between organisms
and the world they inhabit
113

114. TakeTake--Home Message 1.18Home Message 1.18
Although the diversity of
life on earth is tremendous,
the study of life is unified
by the themes of
hierarchical organization
and the power of evolution.
114