Welcome to the scientific
method lecture.
This lecture is an extremely
abridged description
of the scientific method.
So science is defined
as systematic knowledge
of the physical or
material world gained
through observation
and experimentation.
And there are
several major steps.
Depending on who you ask, there
may be one additional or one
removed.
So we have our observation.
I observe that the leaves are
turning orange in the fall.
My question is why are they
turning orange in the fall?
So I hypothesized they're
turning orange in the fall
because there's some sort
of pigment in the leaves
that's changing.
I then conduct an
experiment to test this.
I collect data, I
analyze my data,
and then I can come to
some sort of conclusion
about my hypothesis.
Does my data support
my hypothesis or not?
[YELLING]
We've got to find the
wtich [INAUDIBLE].
[YELLING]
How do you know she is a witch?
She looks like one.
[YELLING]
Bring her forward.
I'm not a witch.
I'm not a witch.
What makes you think
she is a witch?
Oh, she turned me into a newt.
A newt?
I feel better.
Tell me, what do
you do with witches?
Burn!
Burn!
And what do you burn
apart from witches?
More witches.
What?
So why do witches burn?
Because they're made of wood.
Good.
So how do we tell whether
she's made of wood?
Does wood sink in water?
No, no.
It floats!
It floats!
What also floats in water?
Bread.
Apples.
Very small rocks.
Cider.
Grape gravy.
Cherries.
Mud.
Churches!
Churches!
Lead.
A duck.
Exactly.
So, logically--
If she weighs the same as
a duck, she's made of wood.
And therefore--
A witch!
A witch!
[YELLING]
Very good.
We shall use the largest scales.
[YELLING]
Right.
Remove the stops.
[YELLING]
So that was a fun video
covering the steps
of the scientific method.
And in that video, they use
some deductive reasoning
but primarily
inductive reasoning.
So when we're
forming a hypothesis,
we can use deductive
reasoning, inductive reasoning,
or abductive reasoning.
So deductive reasoning is what
we prefer in the sciences.
And basically you
take a broad question
and you narrow it
based on a theory.
So, for example,
all men are mortal.
Harold is a man.
Therefore, Harold is mortal.
So this is one example
of deductive reasoning
that is logical and correct.
But you can also be
logical, but incorrect.
So, for example, all bald
men are grandfathers.
Harold is bald.
Therefore, Harold
is a grandfather.
When we use inductive reasoning,
we go from narrow to broad
and it's based on observations.
So we take these
observations and then
we make assumptions using
inductive reasoning.
So Harold is a grandfather.
Harold is bald.
Therefore, all
grandfathers are bald.
So this can help you
form a hypothesis,
but it's not the
ideal situation.
And then abductive
reasoning is based
on a set of observations
you've made,
and it leads to the
most likely conclusion.
So if you guys know what
KISS means-- Keep It
Simple Stupid--
that's essentially
what abductive reasoning is.
And then, in terms of supporting
or rejecting our hypothesis,
one way that we can do
that is through what's
called falsification,
especially if the hypothesis
has been formed using
inductive reasoning.
And this dates back
to Karl Popper,
who came up with this
example of a black swan.
So if we say that all
the swans we've ever seen
are white-- right, this is
inductive reasoning-- therefore
all swans are white.
But we can falsify
this hypothesis
by finding just a
single black swan.
That's all we need.
And that's essentially the
gist of the scientific method.
