Phil 101: Logic
Fall 2013
Introduction: Today’s Class
• Mechanics of course and expectations
– Syllabus
– Class website and message board
• Introductory readings
– Chapter 0: Introduction and comments about survey
• Homework: Read A Prelude to Logic Ch 1 and Logical Possibility
The Agenda
• Critical Reasoning (“Informal Logic”)
– The real informal fallacies
– A survey of some philosophical problems (this is a philosophy
course!
– Introduction to concepts that figure in the study of formal
logic
• Symbolic Logic
– Propositional Logic: translation, truth tables, truth trees and
proofs
– Introduction to predicate logic (if time permits): translation,
equivalences, identity and definite descriptions
Behavioral Economics & the Real Fallacies
• Bounded Rationality: humans are not (1)
fully informed, (2) strictly rational, (3)
completely self-interested.
• People have two different thinking
systems.
• People are subject to cognitive biases—
systematic errors of perception and
judgment.
• People are good at perceiving causation
but very bad at statistical reasoning…as
the results of our survey show.
Fall 2013 Logic Students Survey
Some Responses
• Sorry to who ever is reading this but I have no clue and I do not want to try
and act like I do.
• Republicans have super kidneys that repel cancer.
• The fact that the states are Republican has nothing to do with it, it is just a
coincedence (good!)
• This could be because they are more conservative, they eat locally grown
foods, eliminating any type of poisoning by artificial foods grown by
chemicals and shipped all around the world.
• Rural areas have less pollution output and Republicans typically lead more
conservative personal lives which would decrease their likelyhood of using
certain drugs. Although, meth abuse is very high in some rural areas so
that explanation may be invalid.
Statistical Explanations
• Because there are not many people there in the first place, so there are
only a few who get kidney cancer
– Comment: we said incidence, i.e. percentage relative to population!
• It's a byproduct of inconsistent sample size. Population bias.
• Since the population of these counties is sparse, the likelihood of there
being less than the normal amount of those with kidney cancer is high.
The greater the population of each county, the more likely the
percentage is closer to the actual percent of overall incidences of kidney
cancer in the United States.
• Moral: One of our biases (systematic errors in reasoning) comes from our
fixation on causal explanations so that we overlook statistical
explanations…and there are many more biases…
A List of Cognitive Biases (Abridged!)
• Loss aversion – "the disutility of giving up an object is greater than the
utility associated with acquiring it”
• Planning fallacy – the tendency to underestimate task-completion times,
often caused by taking the “inside view” rather than comparing to a
reference class in making predictions.
• Zero-risk bias – preference for reducing a small risk to zero over a greater
reduction in a larger risk.
• Halo effect – the tendency for a person's positive or negative traits to
"spill over" from one area of their personality to another in others'
perceptions of them (see also physical attractiveness stereotype).
• Representativeness heuristic – the tendency to estimate the likelihood of
an event by comparing it to an existing prototype we think of as typical.
The List continues…
• Anchoring– the tendency to rely too heavily, or "anchor," on a past
reference or on one trait or piece of information when making decisions.
• Confirmation bias – the tendency to search for or interpret information or
memories in a way that confirms one's preconceptions.[
• Framing effect – drawing different conclusions from the same
information, depending on how or by whom that information is presented.
(includes default reasoning)
• Just-world hypothesis – the tendency for people to want to believe that
the world is fundamentally just, causing them to rationalize an otherwise
inexplicable injustice as deserved by the victim(s).
• Availability heuristic – the tendency to overestimate the likelihood of
events with greater "availability" in memory, which can be influenced by
how recent the memories are, or how unusual or emotionally charged
they may be.
Nudge
Anchoring
Confirmation Bias
Availability Error
Real World Consequences!
Paternalism?
Liberty Limiting Principles
• The Harm Principle
• Legal Moralism
• Legal Paternalism
Libertarian Paternalism
Welcome to Philosophy!
Possibility
At our next class meeting we’ll talk about possibility…