1 Philosophy 12: Logic and Decision Making Mitch Herschbach Spring 2011 UC San Diego 3/29/2011
2 Instructor Mitch Herschbach - Office: HSS Office hours: Tues 1-3pm and by appointment
3 Teaching Assistants Nat Jacobs - Sections: A01: Mon 3-3:50pm Warren Lecture Hall 2207 A03: Fri 10-10:50am Cog Sci Building Office: HSS Office hours: Thurs 1-3pm Jeremy Gomer - Sections: A02: Wed 1-1:50pm Warren Lecture Hall Office: HSS Office Hours: Wed 12-1pm
4 Course website - syllabus - schedule of readings - study guides - paper assignments - lecture slides
5 Course materials 1. Inquiry website and printed course reader 2. i-clicker Classroom Response System Transmitter ( clicker )
6 1. Inquiry website Inquiry website: Login directions and initial login code found in printed course reader, Inquiry into Scientific Reasoning, available at Price Center bookstore - be sure you buy a new reader--used initial logins cannot be reused Printed reader doesn t include all course material--website has text, animation, interactive exercises, and questions
7 2. i>clickers Available at the Price Center bookstore You will need to bring the clickers to every lecture, starting Thursday For more info:
8 Basic operation Turn on the clicker by pressing the bottom On/Off button. - A blue Power light will appear at the top of the remote. Set frequency to AB for this course - While clicker is off, hold power button until blue light flashes - then press A then B When I ask a question in class (and start the timer), select A, B, C, D, or E as your vote.
9 How do you know your vote was received? Check your Vote Status Light: - - Green light = your vote was sent and received Red flashing light = you need to vote again. Not sure you saw the light? Just vote again. Want to change your vote? You can vote again as long as the timer is still going.
10 Organization Basic operation Clickers Registering your i>clicker Registering your i>clicker egistering your i>clicker In order to earn points for your i>clicker responses, you must register your i>clicker online (but don t worry, you will still get the points from before registration). In order to earn points for your i>clicker responses, you must register your i>clicker online (but don t worry, you will still get the points from before registration). Go to For - Fill this, in: you will need (your name), and your your clicker nameid (located on the back of your yourpid clicker, (student belowid) thenumber scan code). your PID number (starting with an A ), - your clicker ID (located on the back of your clicker, below the scan code) click ENTER
11 Other i>clicker info Before using a new clicker for the first time, pull the plastic tab out of the battery compartment. Check out for FAQs or phone for help
12 Course requirements 1. Web-based exercises (5%) 2. Lecture participation (10%) 3. Section participation (5%) 4. Two short (1-2 page) papers (30%) 5. Midterm exam (25%) 6. Final Exam (25%)
13 1. Web-based exercises (5%) These points for timely completion of the interactive exercises and questions on the Inquiry website. Graded on timely completion, not accuracy of responses.
14 the student, what qualifies as appropriate evidence. Classroom Conduct 1. Web-based exercises (5%) Please arrive to class on time. Students should be respectful of their fellow classmates, allowing them to finish before speaking, listening to and respecting classmates' views/opinions. In addition, students must silence all cellular telephones, pagers, and ipods, etc., before entering the classroom. Laptops and other electronic devices may not be used in class, except for lecture note-taking. Readings are titles of modules you re Schedule This expected schedule is tentative to and complete subject to revision. before that day s lecture The numbered reading assignments are modules on the Inquiry website; the numbering is based on the table of contents in your printed reader. You should complete these, including any attached questions, before the assigned class (although subsequent review is certainly encouraged). Date Topic Readings Tues 3/29 Thurs 3/31 Tues 4/5 Thurs 4/7 Tues 4/12 Thurs 4/14 Tues Introduction: The Inquiry Website and Exemplary Scientific Reasoning Elements of science Valid arguments Confirmation, falsification, and fallibility Observation and categories Categorizing phenomena Syllabus 1. Argumentation; 1.1. Invitation to Scientific Reasoning; 1.2. Statements: the atoms of reasoning; 1.3. Justification and arguments 1.4. Some basic valid argument forms 1.5. Evidential relations; 1.6. The fallible character of human knowledge 2. Observation; 2.1. Observation and learning to see 2.2. Categories and taxonomy 2.3 Observational research [Coding Sheet for
15 Interactive Exercises
17 r modules containing questions, the menu on the right side of the page will also c utton that you can click on to Questions access the questions, as depicted in the image belo
19 Checking your progress on Inquiry 19
20 Checking your progress on Inquiry 20
21 2. Lecture participation (10%) Clicker score based on in-class questions that you answer using i>clickers 1 point per question; graded on participation not accuracy Your clicker score will be the percentage of points earned divided by the maximum possible You must have your clicker every class period to get these points no exceptions
22 3. Section participation (5%) Grade based on participation and performance on quizzes in section Sections start next week A01 Mon 3-3:50pm Warren Lecture Hall 2207 A02 Wed 1-1:50pm Warren Lecture Hall 2113 A03 Fri 10-10:50am Cog Sci Building 005
23 4. Two short papers (30%) 1-2 page papers on assigned topics First paper due Thursday, May 12th Second paper due Thursday, May 26th Further details will be posted on course website closer to assignment dates
24 5-6. Midterm and Final Exams Midterm: Tuesday April 26th, in lecture Final exam: Tuesday June 7th, 11:30-2:30pm both are in-class exams consisting of multiple choice, short answer, and essay questions
25 Policy about Deadlines Make-up exams or extended deadlines for the papers will only be given under the most severe circumstances. Any student who wishes to take a make-up exam or needs an extension must inform me (in person or by ) before the deadline. In order to qualify for a make-up exam or an extension, appropriate evidence of the most severe circumstances must be produced by the student. I will determine, in consultation with the student, what qualifies as appropriate evidence.
26 Any questions about the syllabus?
27 Logic and Decision Making If we've been engaging in reasoning and decision-making our whole lives, why have a college course on it? We sometimes engage in bad reasoning, make bad decisions - We're constructed in ways such that we make systematic errors in reasoning and decision making
28 How reliable is vision? Are the table tops the same size or different sizes?
29 How good is human reason? Behind one of these doors I have hidden money, behind the other two a goat You get to pick which one to open. But before you open it, I will open one of the other doors, revealing a goat Now I give you a choice: stay with your first pick, or change to the other. Which is the better option?
30 A Bad Doctor s Visit You go to see your doctor with a puzzling ailment. Your doctor tells you that it is characteristic of a disease that is affecting 1% of the population and if you have it, it means certain death There is a simple test he can perform which is accurate 80% of the time--that is, 20% of the time it gives false positives You agree to the test, and it comes back positive. - Answer: your risk of death is less than 4%! How worried should you be? How likely are you to die?
31 A Bad Doctor s Visit Given 1% infection rate, in a population of 1000 people: - 10 will have the disease, 990 healthy people 80% of those 10 sick people will get an accurate positive test = about 8 people 20% of the 990 healthy people will get a false positive = about 198 people = 206 total positive tests But only 8/206 (3.9%) of those have the disease
32 When is evidence diagnostic? Data from 250 patients: Brain tumor No Brain Tumor Dizzy Not Dizzy Is dizziness associated with brain tumors? Which information is relevant?
33 When is evidence diagnostic? Data from 250 patients: Brain tumor No Brain Tumor Dizzy Not Dizzy What % of dizzy people have brain tumors? What % of non-dizzy people have brain tumors? 160/200 = 80% 40/50 = 80%
34 Sensible Policy Making Imagine that the U.S. is preparing for the outbreak of an unusual disease, which is expected to kill 600 people. Two alternative programs to combat the disease have been proposed: - Program A: 200 people will be saved - Program B: 1/3 chance of saving 600 people and 2/3 chance of saving no one
35 Sensible Policy Making Flood waters are heading toward a town of 600 people. You are on the disaster management board and must choose one of two options: - Program C: 400 people will die - Program D: 1/3 chance that no one will die and 2/3 chance that 600 people will die
36 Sensible Policy Making Imagine that the U.S. is preparing for the outbreak of an unusual disease, which is expected to kill 600 people. Two alternative programs to combat the disease have been proposed: - Program A: 200 people will be saved - Program B: 1/3 chance of saving 600 people and 2/3 chance of saving no one Flood waters are heading toward a town of 600 people. You are on the disaster management board and must choose one of two options: - Program C: 400 people will die - Program D: 1/3 chance that no one will die and 2/3 chance that 600 people will die 72% 28% 22% 78%
37 Good reasoning in science Science is a field where humans have developed practices to help avoid cases of bad reasoning, engage in best kind of reasoning We will explore what makes good/bad reasoning in science, good/bad reasoning in general The focus is not on the scientific examples, but on the principles of reasoning illustrated by these examples
38 Exemplary Reasoning in Science Gregor Mendel s ( ) account of heredity
39 Understanding of heredity prior to Mendel It had been obvious to people for ages that offspring: - are similar to their parents - vary from their parents
40 Understanding of heredity prior to Mendel Animal and plant breeders capitalized on these differences - By controlling mating and eliminating undesired organisms, breeders were able to produce plants and animals with desired traits - By multiply breeding offspring and eliminating variants, breeders could generate pure breeds
41 Gregor Mendel ( ) An Augustinian monk, Mendel studied physics and natural science in Vienna, but lived most of his adult life in an abbey in Altbrünn (now Brno in the Czech Rep) Starting in 1856 he conducted plant breeding experiments in the abbey s garden
42 Mendel s Breeding Experiments Choice of peas as organism to study: naturally selfpollinated but easy to cross-pollinate Mendel introduced the vocabulary of dominant and recessive characters (traits)
43 Reasoning and fallacies Exemplary reasoning in science Introduction Mendel s breeding experiments endel s procedure Mendel s Procedure Develop pure breeding lines: populations that breed true for a particular trait Cross-pollinate between pure Cross-pollinate breeding lines with between alternative pure breeding traits yellow/green lines with seeds, alternative traits smooth/dented (e.g., smooth seeds vs. etc. wrinkled seeds), All members creating of the F1 Fgeneration 1 generation exhibit the dominant All traits. members of the F1 generation exhibit the dominant traits Allow members of the F 1 generation to self-pollinate. Allow members of the F1 generation to self-pollinate, creating F2 generation Topic 1
44 Mendel s Experimental Results Types of Trait Parental Cross F1 Phenotype F2 Phenotypic Ratio F2 Ratio Form of seed Round x Wrinkled Round Round: 5474 Wrinkled: :1 Color of albumen Color of seed coat Form of pods Yellow x Green Violet x White Inflated x Constricted Yellow Violet Inflated Yellow: 6022 Green: 2001 Violet: 705 White: 224 Inflated: 882 Constricted: 299 Color of unripe pods Green x Yellow Green Green: 428 Yellow: 152 Position of flowers Length of stem Axial x Terminal Long x Short Axial Long Axial: 651 Terminal: 207 Long: 787 Short: :1 3.15:1 2.95:1 2.81:1 3.14:1 2.84:1
45 F1 and F2 generations F1 generation: only displayed dominant trait F2 generation produced by self-fertilization of members of the F1 generation: - - Individuals with recessive traits bred pure 1 out of 3 of those showing the dominant character produced only offspring with the dominant character Theoretical problem for Mendel: what could explain these and other patterns he found?
46 Mendel s Hypothesis Behind the characters lay factors - pollen and egg cells each possessed the factor for either the dominant or recessive trait YY Y y yy P What evidence does Mendel have for these factors? Yy Yy F 1 - Only that they account for the inheritance pattern he saw and others he predicted - Without his hypothesis, these other predictions would not have been made Y y Y YY Yy y Yy yy F 2
47 Features of Mendel s Reasoning He designed a study that could reveal structure in the phenomena He found a systematic pattern in the phenomena He proposed a hypothesis that could explain the pattern He supported this hypothesis by both the pattern he initially observed and others which it predicted. These patterns would otherwise be mysterious! Message: Successfully predicting what would otherwise be mysterious is typically the way hypotheses gain support