# NATS 1840 Lecture Notes - Inductive Reasoning, Deductive Reasoning, Environmental Science

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20 Nov 2012
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Science, Technology and the Environment (SC
NATS 1840A) - Tuesday September 11th, 2012
Environmental science and thinking
- How science effects environmental decisions
Definition: Environment
Everything that surrounds you, from just outside your skin to the edge of the
universe.
The environment consists of all those parts of the physical world that helps to
sustain life.
If a part of the environment is under stress, then its ability to sustain life may
be threatened.
Environmental Science:
The study of how the environment works, and of humanity's impact upon it.
A science
Interdisciplinary
Both theoretical and applied
Science
The systematic study of how and why nature works the way it does.
Uses empirical methods to test possible explanations of observations.
Seeks to uncover basic underlying principles so that predictions may be made.
A rational process drawing upon two forms of reasoning...
Inductive
Synthesis, Creativity, Inspiration, Imagination
Deductive
Logic, Self-Consistency, Rigour, Mathematics
What kind of Reasoning?
THIS IS DEDUCTIVE
All first year students drink during frosh week
All NATS 1840 students are in first year
Therefore, all NATS 1840 students will have gotten drunk during frosh week
THIS IS INDUCTIVE
Every university student I've known drank during frosh week
Therefore, all university students drink during frosh week
You can prove a deductive conclusion, but you can't prove an inductive conclusion
The Scientific Method:
Based mainly on inductive reasoning and observations
Deductive reasoning crucial for designing tests (usually called experiments)
1. Observation(s)
2. Question(s)
3. Hypothesis
4. Test hypothesis... do an experiment
5. Critically evaluate results of test
6. Determine if hypothesis is supported or contradicted
7. Disseminate (5) and (6), usually in a refereed (peer reviewed) publication
Hypothesis disproved: question still remains.
Hypothesis supported: deductive consequences of that hypothesis must be tested.
EXAMPLE - Scientific Method
1) Observation: Dog lying on side of road
2) Question: What's wrong with the dog?
3) Hypothesis: The dog is dead (Straight True or False Answer) (Easiest to test)
4) Experiment: Stop and look more closely (RESULT: Breathing => Hypothesis
disproved)
5) Dissemination: "The dog is alive!"
6) Hypothesis: The dog is hurt (Possible answer)
7) Experiment: Examine more carefully; look for damage => Result: No obvious
damage
8) Experiment: Poke the dog => Result: Dog jumps up and starts licking you =>
Hypothesis disproved (weakens the hypothesis)
What is a good scientific statement?
A hypothesis must be falsifiable (can be disproved), at least in principle,
Examples:
The moon is made of cheese
Cell phones cause brain cancer
Sun's energy source is nuclear fusion
A hypothesis that can't be falsified (is untestable) isnt a scientific statement.
God and afterlife
Before the big bang
Some 'conspiracy theories'
First two are valid matters of faith/philosophy, but not science.
SCIENTIFIC EXPERIMENTS:
To be a useful test of a hypothesis, an experiment must be
Controlled
Statistically Significant
Repeatable
Absence of one or more of these criteria means a flawed experiment whose results
shouldn't be trusted until they have been reproduced by a reliable experiment.
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