(There will be some points off if your absence on Tuesday was unexcused.)
Wednesday, February 29, 2012
Fun Tuesday #1: Belief and Evidence
You still have a chance to do the Fun Tuesday assignment if you missed it in class yesterday. Just print out the following worksheet (pdf) and fill in your answer for each statement.
(There will be some points off if your absence on Tuesday was unexcused.)
(There will be some points off if your absence on Tuesday was unexcused.)
Tuesday, February 28, 2012
Murder on the Abductive Express
I think abductive reasoning is the most effective tool we have when faced with the myriad uncertain, ambiguous issues and decisions that everyday life throws our way. Here are some links:
- Here's a paper (pdf) that explains why I disagree with our textbook's explanation of the scientific method. It's important to consider and test multiple possible explanations rather than a single hypothesis.
- (NOTE: Platt uses the word "inductive" in a more general way than we do in class, to refer to any non-deductive kind of reasoning--that is, arguments that don't attempt to absolutely prove their conclusion.)
- I'm 75% through reading this book: Inference to the Best Explanation by Peter Lipton.
- Remember when I was talking about Einstein's theory of general relativity having predictive power? This is what I had in mind.
- Everything you ever wanted to know about William of Ockham and his famous razor.
- Lastly, here's a dinosaur comic murder mystery.
Friday, February 24, 2012
Child Abduction
Psychologist Alison Gopnik gave a great TED talk recently on how children are natural abductive reasoners; playing and making pretend is often about coming up with and testing various hypotheses. Here's the talk:
Gopnik's book, The Philosophical Baby, is great.
Gopnik's book, The Philosophical Baby, is great.
Tuesday, February 21, 2012
Correlatious
Here's yet another stick-figure comic (for those keeping track, that's five total on the blog so far). This one's about correlation.
Saturday, February 18, 2012
The Full Moon Myth
We talked about this on Tuesday: Scientific American has a nice article examining the widely-held belief that the full moon causes strange behavior. Research suggests the full moon doesn't have this effect:"By combining the results of multiple studies and treating them as though they were one huge study—a statistical procedure called meta-analysis—[scientists] have found that full moons are entirely unrelated to a host of events, including crimes, suicides, psychiatric problems and crisis center calls. In their 1985 review of 37 studies entitled 'Much Ado about the Full Moon,' which appeared in one of psychology’s premier journals, Psychological Bulletin, Rotton and Kelly humorously bid adieu to the full-moon effect and concluded that further research on it was unnecessary."One reason the belief persists is a set of natural human cognitive biases in which we perceive correlations where no such correlations exist:
"Illusory correlations result in part from our mind’s propensity to attend to—and recall—most events better than nonevents. When there is a full moon and something decidedly odd happens, we usually notice it, tell others about it and remember it. We do so because such co-occurrences fit with our preconceptions. ... In contrast, when there is a full moon and nothing odd happens, this nonevent quickly fades from our memory. As a result of our selective recall, we erroneously perceive an association between full moons and myriad bizarre events."We'll be discussing these biases more when we study arguments about causes. Here's a cool video by psychological Dan Gilbert on our mistaken expectations:
Thursday, February 16, 2012
Our Inductive Minds
Here are some more thoughtful links on inductive reasoning.
- What are the benefits and dangers of generalizations?
- What makes stereotyping illogical?
- Beware: we often make snap judgments before thinking through things. Then when we do think through things, we just wind up rationalizing our snap judgments.
Friday, February 10, 2012
Quiz You Once, Shame on Me
The first quiz will be held at the beginning of class on Tuesday, February 14th. You will have about 25 minutes to take it.
There will be a multiple choice section, a section on understanding arguments, a section on evaluating deductive arguments, and a section where you provide examples of specific kinds of arguments. Basically, it will look like a mix of the homework, extra credit, and group work we've done in class so far.
The quiz is on what we have discussed in class from chapters 6, 8, and part of 7 of the textbook. Specifically, here's a lot of the stuff we've talked about in class so far that I expect you to know for the quiz:
There will be a multiple choice section, a section on understanding arguments, a section on evaluating deductive arguments, and a section where you provide examples of specific kinds of arguments. Basically, it will look like a mix of the homework, extra credit, and group work we've done in class so far.
The quiz is on what we have discussed in class from chapters 6, 8, and part of 7 of the textbook. Specifically, here's a lot of the stuff we've talked about in class so far that I expect you to know for the quiz:
- definitions of: logic, reasoning, argument, support, sound, valid, deductive, inductive
- understanding arguments
- evaluating arguments (truth and support!)
- deductive args (valid & sound)
- inductive args (there will only be a little on this)
Inductioneering
Here are two dumb things about inductive arguments. First, a video of comedian Lewis Black describing his failure to learn from experience every year around Halloween:
Next, this stick figure comic offers a pretty bad argument. Why is it bad? (Let us know in the comments!)
Next, this stick figure comic offers a pretty bad argument. Why is it bad? (Let us know in the comments!)
Tuesday, February 7, 2012
Group Presentations: 9:25 a.m. Class
Here are the assigned groups for the group presentations on fallacies for the 9:25 a.m. class, along with your topics and the tentative date of each presentation (those dates may be pushed back):
During our section on fallacies, groups of 4-5 students will present short lessons on two specific fallacies that their members have researched on their own.
Groups are free to choose how to present their topic to the rest of the class. Be creative! Think about puppets, posters, cartoons, songs, skits, handouts, whatever. Part of your grade will be based on how creative your presentation is. Remember, though, that you are expected to teach these fallacies to the rest of the class. Although they will have read about your fallacies in our textbook, the rest of class will probably not be as familiar with the material you are presenting as your group is. Here are some helpful suggestions of things to include in your presentation:
The presentation is worth 150 points (15% of your overall grade). Except in unusual circumstances, each group member shall receive the same grade. There will not be any time set aside in class for groups to research and prepare for their presentation, so you should meet outside class to work on this presentation.
- Ad Hominem & Appeal to Force (February 28th): Dale, Jeff, Kenniqua, Yasmine, Zach
- Appeal to Pity & Popular Appeal (February 28th): Brenda, Jon, José, Sean
- Appeal to Ignorance & Begging the Question (March 1st): Courtney, Frank, Kevin, Steve W.
- Straw Man & Red Herring (March 1st): Chaz, Donnie, Giselle, Jason, Samantha
- Appeal to Authority & False Dilemma (March 20th): Daniel, Jasmaine, Joey, John, Maggie
- Slippery Slope & The Naturalistic Fallacy (March 20th): Akin, Beth, Brittany, Heather, Stephen C.
During our section on fallacies, groups of 4-5 students will present short lessons on two specific fallacies that their members have researched on their own.
Groups are free to choose how to present their topic to the rest of the class. Be creative! Think about puppets, posters, cartoons, songs, skits, handouts, whatever. Part of your grade will be based on how creative your presentation is. Remember, though, that you are expected to teach these fallacies to the rest of the class. Although they will have read about your fallacies in our textbook, the rest of class will probably not be as familiar with the material you are presenting as your group is. Here are some helpful suggestions of things to include in your presentation:
- DEFINITION: A formal definition of each fallacy
- A slow, clear explanation in plain English of what those definitions mean
- EXAMPLES: Lots of specific examples of arguments that commit each fallacy
- Explanations of how it is that these example arguments commit the fallacy
- WHY BAD?: An explanation of why each fallacy is a mistake in reasoning
The presentation is worth 150 points (15% of your overall grade). Except in unusual circumstances, each group member shall receive the same grade. There will not be any time set aside in class for groups to research and prepare for their presentation, so you should meet outside class to work on this presentation.
Monday, February 6, 2012
Group Presentations: 8:00 a.m. Class
Here are the assigned groups for the group presentations on fallacies for the 8:00 a.m. class, along with your topics and the tentative date of each presentation (those dates may be pushed back):
During our section on fallacies, groups of 4-5 students will present short lessons on two specific fallacies that their members have researched on their own.
Groups are free to choose how to present their topic to the rest of the class. Be creative! Think about puppets, posters, cartoons, songs, skits, handouts, whatever. Part of your grade will be based on how creative your presentation is. Remember, though, that you are expected to teach these fallacies to the rest of the class. Although they will have read about your fallacies in our textbook, the rest of class will probably not be as familiar with the material you are presenting as your group is. Here are some helpful suggestions of things to include in your presentation:
The presentation is worth 150 points (15% of your overall grade). Except in unusual circumstances, each group member shall receive the same grade. There will not be any time set aside in class for groups to research and prepare for their presentation, so you should meet outside class to work on this presentation.
- Ad Hominem & Appeal to Force (February 28th): Brandon, Christie, Felix, John
- Appeal to Pity & Popular Appeal (February 28th): Ashley, Ryan, Stephanie, Tevin
- Appeal to Ignorance & Begging the Question (March 1st): Evan, Jim, Joshani, Katie
- Straw Man & Red Herring (March 1st): Kayla, Leanne, Michael, Nicole, Victoria
- Appeal to Authority & False Dilemma (March 20th): Ericca, Jordan, Luke, Sheena
- Slippery Slope & The Naturalistic Fallacy (March 20th): Alberto, Frank, Ileana, Kristin
During our section on fallacies, groups of 4-5 students will present short lessons on two specific fallacies that their members have researched on their own.
Groups are free to choose how to present their topic to the rest of the class. Be creative! Think about puppets, posters, cartoons, songs, skits, handouts, whatever. Part of your grade will be based on how creative your presentation is. Remember, though, that you are expected to teach these fallacies to the rest of the class. Although they will have read about your fallacies in our textbook, the rest of class will probably not be as familiar with the material you are presenting as your group is. Here are some helpful suggestions of things to include in your presentation:
- DEFINITION: A formal definition of each fallacy
- A slow, clear explanation in plain English of what those definitions mean
- EXAMPLES: Lots of specific examples of arguments that commit each fallacy
- Explanations of how it is that these example arguments commit the fallacy
- WHY BAD?: An explanation of why each fallacy is a mistake in reasoning
The presentation is worth 150 points (15% of your overall grade). Except in unusual circumstances, each group member shall receive the same grade. There will not be any time set aside in class for groups to research and prepare for their presentation, so you should meet outside class to work on this presentation.
Sunday, February 5, 2012
An Argument's Support
One of the trickier concepts to understand in this course is the structure (or support) of an argument. This is a more detailed explanation of the term. If you've been struggling to understand this term, the following might help you.
An argument's structure is its underlying logic; the way the premises and conclusion logically relate to one another. The structure of an argument is entirely separate from the actual meaning of the premises. For instance, the following three arguments, even though they're talking about different things, have the exact same structure:
1) All tigers have stripes.
Tony is a tiger.
Tony has stripes.
2) All humans have wings.
Sean is a human.
Sean has wings.
3) All blurgles have glorps.
Xerxon is a blurgle.
Xerxon has glorps.
There are, of course, other, non-structural differences in these three arguments. For instance, the tiger argument is overall good, since it has a good structure AND true premises. The human/wings argument is overall bad, since it has a false premise. And the blurgles argument is just crazy, since it uses made up words. Still, all three arguments have the same underlying structure (a good structure):
All A's have B's.
x is an A.
x has B's.
Evaluating the structure of an argument is tricky. Here's the main idea regarding what counts as a good structure: the premises provide us with enough information for us to figure out the conclusion from them. In other words, the premises, if they were true, would logically show us that the conclusion is true. So, if you believed the premises, they would convince you that the conclusion is worth believing, too.
Note I did NOT say that the premises are actually true in a good-structured argument. Structure is only about truth-preservation, not about whether the premises are actually true or false. What's "truth preservation" mean? Well, truth-preserving arguments are those whose structures are such that if you stick in true premises, you get a true conclusion.
The premises you've actually stuck into this particular structure could be good (true) or bad (false). That's what makes evaluating an arg's structure so weird. To check the structure, you have to ignore what you actually know about the premises being true or false.
Good Structured Arguments (Valid)
If we assume that all the premises are true, then the conclusion will also be true for an argument to have a good structure. Notice we are only assuming truth, not guaranteeing it. Again, this makes sense, because we’re truth-preservers: if the premises are true, the conclusion that follows will be true.
EXAMPLES:
1) All humans are mammals.
All mammals have hair.
All humans have hair.
2) If it snows, then it’s below 32 degrees.
It is snowing right now.
It’s below 32 degrees right now.
3) All humans are mammals.
All mammals have wings.All humans have wings.
4) Either Yao is tall or Spud is tall.
Yao is not tall.
Therefore, Spud is tall.
Even though arguments 3 and 4 are ultimately bad, they still have good structure (their underlying form is good). The second premise of argument 3 is false—not all mammals have wings—but it has the same exact structure of argument 1—a good structure. Same with argument 4: the second premise is false (Yao Ming is about 7 feet tall), but the structure is good (it’s either this or that; it’s not this; therefore, it’s that).
To evaluate the structure, then, assume that all the premises are true. Imagine a world in which all the premises are true. In that world, are you able to figure out from the premises that the conclusion is also true? Or can you imagine a scenario in that world in which the premises are true, but the conclusion is still false? If you can imagine this situation, then the argument's structure is bad. If you cannot, then the argument is truth-preserving (inputting truths gives you a true output), and thus the structure is good.
Bad Structured Arguments (Invalid)
In an argument with a bad structure, you can’t draw the conclusion from the premises – the premises don’t give you enough information. Bad structured arguments do not preserve truth.
EXAMPLES:
1) All humans are mammals.
All whales are mammals.
All humans are whales.
2) If it snows, then it’s below 32 degrees.
It doesn’t snow.
It’s not below 32 degrees.
3) All humans are mammals.
All students in our class are mammals.
All students in our class are humans.
4) Either Yao is tall or Spud is short.
Yao is tall.
Spud is short.
Even though arguments 3 and 4 have all true premises and a true conclusion, they are still have a bad structure, because their form is bad. Argument 3 has the same exact structure as argument 1—a bad structure (it doesn’t preserve truth).
Even though in the real world the premises and conclusion of argument 3 are true, we can imagine a world in which all the premises of argument 3 are true, yet the conclusion is false. For instance, imagine that our school starts letting dogs take classes. The second premise would still be true, but the conclusion would then be false.
The same goes for argument 4: even though Spud is short (Spud Webb is around 5 feet tall), this argument doesn’t guarantee this. The structure is bad (it’s either this or that; it’s this; therefore, it’s that, too.). We can imagine a world in which Yao is tall, the first premise is true, and yet Spud is tall, too.
An argument's structure is its underlying logic; the way the premises and conclusion logically relate to one another. The structure of an argument is entirely separate from the actual meaning of the premises. For instance, the following three arguments, even though they're talking about different things, have the exact same structure:
1) All tigers have stripes.
Tony is a tiger.
Tony has stripes.
2) All humans have wings.
Sean is a human.
Sean has wings.
3) All blurgles have glorps.
Xerxon is a blurgle.
Xerxon has glorps.
There are, of course, other, non-structural differences in these three arguments. For instance, the tiger argument is overall good, since it has a good structure AND true premises. The human/wings argument is overall bad, since it has a false premise. And the blurgles argument is just crazy, since it uses made up words. Still, all three arguments have the same underlying structure (a good structure):
All A's have B's.
x is an A.
x has B's.
Evaluating the structure of an argument is tricky. Here's the main idea regarding what counts as a good structure: the premises provide us with enough information for us to figure out the conclusion from them. In other words, the premises, if they were true, would logically show us that the conclusion is true. So, if you believed the premises, they would convince you that the conclusion is worth believing, too.
Note I did NOT say that the premises are actually true in a good-structured argument. Structure is only about truth-preservation, not about whether the premises are actually true or false. What's "truth preservation" mean? Well, truth-preserving arguments are those whose structures are such that if you stick in true premises, you get a true conclusion.
The premises you've actually stuck into this particular structure could be good (true) or bad (false). That's what makes evaluating an arg's structure so weird. To check the structure, you have to ignore what you actually know about the premises being true or false.
Good Structured Arguments (Valid)
If we assume that all the premises are true, then the conclusion will also be true for an argument to have a good structure. Notice we are only assuming truth, not guaranteeing it. Again, this makes sense, because we’re truth-preservers: if the premises are true, the conclusion that follows will be true.
EXAMPLES:
1) All humans are mammals.
All mammals have hair.
All humans have hair.
2) If it snows, then it’s below 32 degrees.
It is snowing right now.
It’s below 32 degrees right now.
3) All humans are mammals.
All mammals have wings.All humans have wings.
4) Either Yao is tall or Spud is tall.
Yao is not tall.
Therefore, Spud is tall.
Even though arguments 3 and 4 are ultimately bad, they still have good structure (their underlying form is good). The second premise of argument 3 is false—not all mammals have wings—but it has the same exact structure of argument 1—a good structure. Same with argument 4: the second premise is false (Yao Ming is about 7 feet tall), but the structure is good (it’s either this or that; it’s not this; therefore, it’s that).
To evaluate the structure, then, assume that all the premises are true. Imagine a world in which all the premises are true. In that world, are you able to figure out from the premises that the conclusion is also true? Or can you imagine a scenario in that world in which the premises are true, but the conclusion is still false? If you can imagine this situation, then the argument's structure is bad. If you cannot, then the argument is truth-preserving (inputting truths gives you a true output), and thus the structure is good.
Bad Structured Arguments (Invalid)
In an argument with a bad structure, you can’t draw the conclusion from the premises – the premises don’t give you enough information. Bad structured arguments do not preserve truth.
EXAMPLES:
1) All humans are mammals.
All whales are mammals.
All humans are whales.
2) If it snows, then it’s below 32 degrees.
It doesn’t snow.
It’s not below 32 degrees.
3) All humans are mammals.
All students in our class are mammals.
All students in our class are humans.
4) Either Yao is tall or Spud is short.
Yao is tall.
Spud is short.
Even though arguments 3 and 4 have all true premises and a true conclusion, they are still have a bad structure, because their form is bad. Argument 3 has the same exact structure as argument 1—a bad structure (it doesn’t preserve truth).
Even though in the real world the premises and conclusion of argument 3 are true, we can imagine a world in which all the premises of argument 3 are true, yet the conclusion is false. For instance, imagine that our school starts letting dogs take classes. The second premise would still be true, but the conclusion would then be false.
The same goes for argument 4: even though Spud is short (Spud Webb is around 5 feet tall), this argument doesn’t guarantee this. The structure is bad (it’s either this or that; it’s this; therefore, it’s that, too.). We can imagine a world in which Yao is tall, the first premise is true, and yet Spud is tall, too.
Friday, February 3, 2012
Evaluating Deductive Arguments
Here are the answers to the handout on evaluating deductive arguments that we did as group work in class.
1) All bats are mammals.
All mamammals live on earth.
All bats live on earth.
All frogs are amphibians.
No frogs are humans.
All bats have wings.
All mammals have wings.
All bearded people are mean.
Some dads are mean.
Some people ate tacos yesterday.
Oprah Winfrey ate tacos yesterday.
All humans are mammals.
All students in here are humans.
9) All hornets are wasps.
All wasps are insects.
All insects are scary.
All hornets are scary.
Sean is singing right now.
Students are cringing right now.
Sean isn't singing right now.
Students aren't cringing right now.
Most humans are shorter than 7 feet tall.
Most students in here are shorter than 7 feet tall.
Bush was either a great prez or the greatest prez.
Bush wasn’t the greatest prez.
Bush was a great prez.
Students are cringing right now.
Sean is singing right now.
Students aren't cringing right now.
Sean isn't singing right now.
Life isn't meaningless.
There is a God.
1) All bats are mammals.
All mamammals live on earth.
All bats live on earth.
P1- true
P2- true
support- valid
overall- sound
2) All email forwards are annoying.
Some email forwards are false.
Some annoying things are false.
All females in this class are humans.
All males in this class are females.
Some email forwards are false.
Some annoying things are false.
P1- questionable ("annoying" is subjective)3) All males in this class are humans.
P2- true
support- valid (the premises establish that some email forwards are both annoying and false; so some annoying things [those forwards] are false)
overall- unsound (bad first premise)
All females in this class are humans.
All males in this class are females.
P1- true4) No humans are amphibians.
P2- true
support- invalid (the premises only tell us that males and females both belong to the humans group; we don't know enough about the relationship between males and females from this)
overall- unsound (bad support)
All frogs are amphibians.
No frogs are humans.
P1- true5) All bats are mammals.
P2- true
support- valid (the premises say that frogs belong to a group that humans can't belong to, so it follows that no frogs are humans)
overall- sound
All bats have wings.
All mammals have wings.
P1- true6) Some dads have beards.
P2- true (if interpreted to mean "All bats are the sorts of creatures who have wings.") or false (if interpreted to mean "Each and every living bat has wings," since some bats are born without wings)
support- invalid (we don't know anything about the relationship between mammals and winged creatures just from the fact that bats belong to each group)
overall- unsound (bad support)
All bearded people are mean.
Some dads are mean.
P1- true7) Oprah Winfrey is a person.
P2- questionable ("mean" is subjective)
support- valid (if all the people with beards were mean, then the dads with beards would be mean, so some dads would be mean)
overall- unsound (bad 2nd premise)
Some people ate tacos yesterday.
Oprah Winfrey ate tacos yesterday.
P1- true8) All students in here are mammals.
P2- true (you might not have directly seen anyone eat tacos, but you have a lot of indirect evidence... with all the Taco Bells, Don Pablos, etc., surely lots of people ate tacos yesterday)
support- invalid (the 2nd premise only says some ate tacos; Oprah could be one of the people who didn't)
overall- unsound (bad support)
All humans are mammals.
All students in here are humans.
P1- true
P2- true
support- invalid (the premises only tell us that students and humans both belong to the mammals group; we don't know enough about the relationship between students and humans from this; for instance, what if a dog were a student in our class?)
overall- unsound (bad structure)
9) All hornets are wasps.All wasps are insects.
All insects are scary.
All hornets are scary.
P1- true!10) If Sean sings, then students cringe.
P2- true
P3- questionable ("scary" is subjective)
support- valid (same structure as in argument #1, just with an extra premise)
overall- unsound (bad 3rd premise)
Sean is singing right now.
Students are cringing right now.
P1- questionable (since you haven't heard me sing, you don't know whether it's true or false)11) If Sean sings, then students cringe.
P2- false
support- valid
overall- unsound (bad premises)
Sean isn't singing right now.
Students aren't cringing right now.
P1- questionable (again, you don't know)12) All students in here are humans.
P2- true
support- invalid (from premise 1, we only know what happens when Sean is singing, not when he isn't singing; students could cringe for a different reason)
overall- unsound (bad 1st premise and structure)
Most humans are shorter than 7 feet tall.
Most students in here are shorter than 7 feet tall.
P1- true13) (from Stephen Colbert)
P2- true!
support- invalid (the premises state a strong statistical generalization over a large population, and the conclusion claims that this generalization holds for a much smaller portion of that population; even though it's likely that most students in here are, in fact, shorter than 7 feet tall, it nevertheless could be true that the humans in here are a statistical anomaly)
overall- unsound (bad support)
Bush was either a great prez or the greatest prez.
Bush wasn’t the greatest prez.
Bush was a great prez.
P1- questionable ("great" is subjective)14) If Sean sings, then students cringe.
P2- questionable ("great" is subjective)
support- valid (it's either A or B; it's not A; so it's B)
overall- unsound (bad premises)
Students are cringing right now.
Sean is singing right now.
P1- questionable (again, you don't know)15) If Sean sings, then students cringe.
P2- false
support- invalid (from premise 1, we only know that Sean singing is one way to guarantee that students cringe; just because they're cringing doesn't mean Sean's the one who caused it; again, students could cringe for a different reason)
overall- unsound (bad premises and structure)
Students aren't cringing right now.
Sean isn't singing right now.
P1- questionable (again, you don't know)16) If there is no God, then life is meaningless.
P2- true
support- valid
overall- unsound (bad 1st premise)
Life isn't meaningless.
There is a God.
P1- questionable (that's not an obvious claim to prove or disprove)
P2- questionable (again, that's not an obvious claim to prove or disprove)
support- valid (the same structure as argument #15)
overall- unsound (bad premises)
Thursday, February 2, 2012
Wednesday, February 1, 2012
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