EDWARD'S LECTURE NOTES:
More notes at http://tanguay.info/learntracker
C O U R S E 
Fake News, Facts, and Alternative Facts
Josh Pasek, University of Michigan
https://www.edx.org/course/fake-news-facts-alternative-facts-michiganx-teachout-2x
C O U R S E   L E C T U R E 
How We Know Things
Notes taken on April 28, 2017 by Edward Tanguay
to know if something is true, we need to know how we know what we know
this is actually a difficult question
has a massive literature in philosophy
what do we mean by knowledge
justified true beliefs
from very early philosophy people have been skeptical that we can know anything at all
Socrates: "I know one thing: that I know nothing."
to get around this problem, René Descartes, tried to prove what it was that one could actually prove that one knows
how do you show that you indeed know something
"I know that I exist because I'm thinking"
it could be that you are a brain in a vat
you could be dreaming
we might all be in a computer simulation set up by a society of the future trying to figure out how things might have gone differently
you can't show any of this for certain
in theory, as a Cartesian skeptic, you realize you know very few things about the world, e.g. that you exist because you think and 1+1=2
in practice, however, you don't want to be a Cartesian skeptic, because it would be very difficult to live life if you doubted everything equally, e.g. that the food you eat or the floor you walk on is not real
and if you don't want be a Cartesian skeptic, you need to understand that we know what we know based on evidence we have for different assertions, and how strong that evidence needs to be depends on the reason we need this particular piece of information, e.g.
to make a traffic stop requires reasonable suspicion
to make an arrest requires probably cause
to convict someone of a crime requires evidence that is beyond a reasonable doubt
five key types of evidence
1. proof
anything that can be determined through mathematical or logical reasoning
a. logical proofs
since thinking imples existence, since I am thinking, I know that I exist
b. mathematical proofs
1+1=2
2. claims
statements we have heard or read from others
examples
New York is American's largest city (true)
It takes seven years to digest gum. (false)
three things to evaluate claims
a. plausibility
is it relatively likely
b. expertise of the claimant
to what extent does the person who made the claim have the ability to know what they are claiming
e.g. is the explanation of how a root canal is performed coming from your dentist or a friend
c. reliability of the claimant
how accurate as the source been in the past
how often has the source admitted and correct errors in the past
3. experience
things we have watched or directly encountered
compare to claim which are indirect
examples
it hurts to touch hot things
John ate lunch at noon
reliability of observations
maybe John was not eating lunch but was having a snack and ate lunch later
consider any optical illusions
4. inference
extensions that we make from other evidence
examples
object permanence
babies think objects go in and out of existence depending on if they are currently experiencing them
evolutionary theory
making the logical step from observed evidence such as the fossil record to explain what has happened in the past
John likes pizza because I saw him eating pizza
quality depends on
quality of evidence
how big the leap of inference is
how many times did you see Tom eat pizza
5. deductive testing
the scientific method
the most systematic way we have of gaining information
we make a hypothesis, set up a test, and have numerous people who doubt the results test it
examples of hypotheses to test
acetaminophen outperforms a placebo
get two groups and give them both
the Earth goes around the Sun
gather information about how planets, stars, and Sun moves around in the sky and make deductions
the television is not broken
make sure it is plugged in
make sure the remote control has a battery
make sure the battery is not dead
quality of testing
how rigorously was the scientific method adhered to