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Title: Scientific Reasoning
Description: A look at Scientific reasoning and how it works. This document examines how scientists reasons and how they arrive at their different conclusions. You will also find that we use these reasoning on a daily basis and it can help identify which type of reasoning you yourself uses more often.
Description: A look at Scientific reasoning and how it works. This document examines how scientists reasons and how they arrive at their different conclusions. You will also find that we use these reasoning on a daily basis and it can help identify which type of reasoning you yourself uses more often.
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Scientific Reasoning
Chapter 2
Scientists often tell us things about the world
that we would not otherwise have believed:
What exactly is the nature of scientific
reasoning?
• How much confidence should we place in
the inferences scientists make?
•
Deduction
Deductive reasoning – a type of reasoning in
which the existence of an appropriate relation
between premises and conclusion, namely that if the
premises are true, the conclusion must be true too:
Premise 1: All NCU teachers are Christians
Premise 2: Jonathan is a NCU teacher
Conclusion: Therefore, Jonathan is a Christian
Whether that premises are actually true is a different
matter, which doesn’t affect the status of the
inference as deductive
...
The first five eggs in the box were rotten
All the eggs have the same best-before date stamped on them
-------------------------------------------------------------------------------------------Therefore, the sixth egg will be rotten
It is quite conceivable that the sixth egg (which we haven’t
examined) will be perfectly good
...
When we reason deductively, we can be certain that if we
start with true premises, we will end up with a true
conclusion
...
Other examples of inductive reasoning:
• When you turn the steering wheel of your car
anticlockwise, you assume the car will go to the left not the
right
...
Newton did not arrive at this principle by
examining every single body in the whole universe – he
couldn’t possibly have
...
• What this means is that the scientists have tested the
maize on a large number of humans, and none of them have
come to any harm
...
• The word ‘proof’ should strictly only be used when we are
dealing with deductive inferences
...
Karl Popper
Popper’s basic argument was that it is not possible to prove
that a scientific theory is true from a limited data sample, it is
possible to prove that a theory is false
...
The major problem with Popper’s argument is that a scientist
is also interested in proving his/her own theory to be true –
setting up the use of inductive inference
...
Hume argued that we use induction all the
time in everyday life and in science, but he insists this was
just a matter of brute animal habit
...
Uniformity of nature (UN) – The assumption that objects
we haven’t examined will be similar, in the relevant respects,
to objects of the same sort that we have examined:
• The fact that the sun has risen every day up until now may
not prove that it will rise tomorrow, but surely it gives us
very good reason to think it will
...
• It is easy to imagine a universe where nature is not
uniform, but changes its course randomly from day to day
...
• Hume concludes that our confidence in induction is just
blind faith – it admits of no rational justification whatever
...
If Hume is right,
the foundations on which science is built do not look as
solid as we might have hoped (Hume’s problem)
...
• It is natural to think that although the premises of an
inductive inference do not guarantee the truth of the
conclusion, they do make it quite probable
...
Inference to the best explanation (IBE)
The cheese in the pantry has disappeared, apart from a few
crumbs
Scratching noises were heard coming from the pantry last night
...
• This inference is non-deductive – the premises do not
entail the conclusion
...
• The mouse hypothesis and the maid hypothesis can both
account for the missing cheese
...
Probability and induction
Frequency interpretation – equates probabilities with
proportions, or frequencies
...
Subjective interpretation – takes the probability to be a
measure of the strength of our personal opinions
...
Example: I am very
confident that Brazil will win the World Cup; I am
extremely confident that ‘Jesus is coming again’; There is a
low probability that a global environmental disaster can be
averted
...
A
statement’s probability is the measure of the strength of
the evidence in its favour
...
(Mendelian Genetics)
• The hope that it might shed some light on inductive
inference, in particular on Hume’s problem
...
On the frequency interpretation, to say it is highly probable
that all objects obey Newton’s law is to say it is highly
probable that all objects obey the law
...
The logical interpretation suggests that the premises of an
inductive inference cab make the conclusion highly
probable, even if they cannot guarantee its truth
...
But recent reports about contaminants such
as mercury and polychlorinated biphenyls, or PCBs, have prompted some
health experts to rethink their advice about seafood
...
For Seattle cardiologist Florence Sheehan, M
...
, it isn't just her patients
she worries about
...
"Ours has a history of high
cholesterol," Sheehan says
...
"
Lately, she finds herself scanning medical journals and government advisories
to stay abreast of fish safety issues
...
"The key is to
place the benefits and risks into perspective," Sheehan says
...
It's just that some types of seafood can be
risky for certain groups of people
...
Since exposure to high levels of mercury can cause neurological
damage in a growing fetus, the Food and Drug Administration
continues to issue related seafood safety advisories to pregnant
women and young children
...
While fresh and canned tuna didn't make the
FDA's list, many experts say pregnant women may be better off
limiting fresh tuna steaks and canned albacore, or "white," tuna to
one meal per week or less, since these large fish can harbor
mercury levels close to the one part per million threshold the
FDA deems safe
...
) The
American Medical Association recently encouraged the FDA to
require supermarkets to post warning signs about mercury near
canned tuna as well as at the fish counter
...
com: Risks,
benefits of 8 most popular U
...
seafood
Being aware of mercury is also a good idea for those who aren't
pregnant
...
Hightower, M
...
,
performed a yearlong study of 123 of her patients, she found that a
steady diet of high-mercury fish caused serious symptoms
such as headaches, hair loss, problems with concentration, and high
blood levels of mercury
...
Purdue University seafood expert Charles Santerre, Ph
...
, thinks the key to
minimizing health risks for any food is to aim for variety
...
"But if you eat them once a
month [and trade off with] some other low-mercury fish, it shouldn't be a
problem
...
On his list of safe, low-mercury options: shrimp, salmon,
pollock, farm-raised catfish, tilapia, flatfish (flounder, sole, plaice), scallops,
haddock, farm-raised trout, herring, crawfish, mullet, oysters, ocean perch,
sardines, squid, white fish, and anchovies
...
"Fish oils are
pure," says Connor
...
Currently, the American Heart Association
recommends 1,000 milligrams of fish oil supplements
per week for people with heart disease
...
Title: Scientific Reasoning
Description: A look at Scientific reasoning and how it works. This document examines how scientists reasons and how they arrive at their different conclusions. You will also find that we use these reasoning on a daily basis and it can help identify which type of reasoning you yourself uses more often.
Description: A look at Scientific reasoning and how it works. This document examines how scientists reasons and how they arrive at their different conclusions. You will also find that we use these reasoning on a daily basis and it can help identify which type of reasoning you yourself uses more often.