Friends of Rogers Park Library

Continue discussing Steven Pinker’s Rationality: What It Is, Why It Seems Scarce, Why It Matters, June 27, 2026, from 2:00 PM to 4:00 PM Central Standard Time using Google Meet.
On May 30, 2026, our group of four continued exploring Steven Pinker’s Rationality and delved deeply into the utility curve and its profound economic and psychological implications. First, we examined a famous wager made by the philosopher and mathematician Blaise Pascal, who reframed the existence of God as a probability problem. His sure bet is that God exists: If He exists, you gain everything; if He does not, you lose nothing.
Taking this expected-value framework to a casino, how do different games of chance compare? Shooting craps is a dice game where players bet on the outcome of a roll using two six-sided dice. The casino may require $1 to play the game, and will give $4 for a roll of 7. What’s the utility of playing this game? There is a ⅙ chance to win $4 and ⅚ chance of losing $1, the utility is (⅙)($4) + (⅚)(-$1), giving you a -$0.17 loss over the course of many throws of the dice. In a game of roulette, it takes $1 to play, and the winning choice will give $35. There is a 1/37 chance of spinning a 7 and a 36/37 chance of losing, giving the utility of (1/37)($35) + (36/37)(-$1), giving you -$0.027 loss over many spins. The odds favor the casino with either game, but for the gambler, roulette can be less aggravating.
Utility is not reserved solely for games of chance; it serves as a framework to align our actions with our values outside the casino. We often discover our true values simply by observing how we act—measuring how much we care about everything from providing for our children to returning a lost wallet. But is this truly rational decision-making?
Assumptions are made in the study of making rational choices and used in the same manner Euclid used axioms to construct geometric theorems. Commensurability is the ability to compare disparate things using a common standard to determine if their values are "in the same ballpark". Transitivity is if $A > $B and $B > $C, then $A > $C. Closure is the property where an operation applied to members of a group always yields another member of that same group. Consolidation unifies disparate data into a cohesive, single entity. Independence is the principle that separate events do not influence one another (e.g., a coin flip has no memory of the previous flip). Consistency is the absence of internal contradictions; truth cannot contradict other truths.
To build a smooth, traditional utility curve—where utility sits on the y-axis and wealth/money sits on the x-axis—a person's behavior must strictly adhere to these pillars. The resulting concave graph rises steeply at first but flattens out at higher wealth levels, demonstrating diminishing marginal utility or diminishing returns.
However, psychologists Daniel Kahneman and Amos Tversky did not just use the traditional economic utility curve—they changed it to include losses in the financial deliberations. They found that different income levels do not share the same utility curve; while these curves all possess the general mathematical property of flattening as wealth increases, the steepness and the exact point of flattening shift dramatically depends on whether a person is low-, middle-, or high-income, with the implications that $100 inherently means much more to a low-income individual than to a high-income one.
To model actual human behavior, they replaced the smooth concave curve with an asymmetrical, S-shaped curve re-centered around a subjective reference point. While a traditional symmetric curve implies the joy of gaining $100 matches the sadness of losing it, Kahneman and Tversky proved that the pain of a loss is roughly twice as intense as the pleasure of an equivalent gain on the steepest part of the curve for low-income individuals, but becomes less pronounced for those with high incomes, implying low-income individuals are more risk-adverse and those with higher incomes are more risk-seeking.
The utility curve successfully sells commercial insurance, enticing us to pay a small premium today to avoid catastrophic financial ruin tomorrow. But can this mathematical curve scale to the ethical weight of treating a child with cancer? Can it resolve the polarizing debates surrounding the economic costs of climate change or the implementation of nuclear power? It is unlikely, as proponents and opponents operate from fundamentally mismatched utility curves. Is there a way to merge these conflicting curves to end societal disputes?
We invite you to find out more about the bell-shaped distribution and signal-to-noise ratios in Steven Pinker’s Rationality: What It Is, Why It Seems Scarce, Why It Matters, BF441.P56 2021 on June 27, 2026, from 2:00 PM to 4:00 PM. Send a request for the meeting link, and I will send it to you. I create a new Google Meet link for each discussion. Captions are available on Google Meet. Anyone can enable closed captioning for their screen, and I will show how to turn on captions for each meeting.
I hope to see you on June 27, 2026,
Kang

A post-Memorial Day documentary screening featuring the producer of the film and war veterans will be present at the Rogers Park Library this Saturday, May 30th, Noon - 1:30 pm. Don't miss this special event! More information available at this link! https://chipublib.bibliocommons.com/events/69d40e4bf29b90618efd8be6

Origami Airplane Workshop: Fold, Fly, and Discover the Art of Paper Aviation Saturday, Sunday, May 31, at 1:30-2:30 pm
2nd Floor, Community Room, Rogers Park Library, 6907 N. Clark Street, Chicago, IL 60626
Join us for a fun and engaging Origami Airplane Workshop, where creativity meets simple engineering and takes flight! In this hands-on workshop, participants will learn how to transform a single sheet of paper into beautifully crafted airplanes while exploring the principles of flight. Try to make a paper airplane that stays aloft longer, hit a target or fly the longest distance.
Whether you're a beginner or a paper-folding enthusiast, this workshop offers something for everyone. Come ready to fold, experiment, and watch your creations soar!
Ages 7 and above. Registration is full but use the link below to get on the wait list:
https://chipublib.bibliocommons.com/events/69e8fb6cbd5c392c7645d856

Clothing Drive at the Bezazian Library
1226 W. Ainslie Street
May 30, 2026, 2 PM to 4:30 PM

Now is a good time to check your closets and donate good clothing you no longer need to someone who will welcome it! Please check the list in the poster above to see what is most needed by 19th District Mutual Aid.
Co-sponsored with the Friends of Bezazian Library.

Talk With Michelle Cox

Saturday, May 30, 10:00AM - 12:00PM
Logan Square Branch Library
3030 West Fullerton
Sponsored by Friends Of The Logan Square Library

Come hear Cox discuss her inspiration for the novels, the setting, the characters, and what she loves most about the Jane Austen connection. There will be plenty of time for Q and A, so come with questions!

Michelle Cox has always been obsessed with stories of the past and has spent a lifetime collecting them. She is the award-winning author of historical fiction, including the Henrietta and Inspector Howard series, The Fallen Woman's Daughter, and now The Merriweather series, which charmingly reimagines Jane Austen’s novels in the
fictional town of Merriweather, Wisconsin in the 1930s.

Rescued Me: My Life with Four-Legged Friends
Saturday, May 30, 10:30-11:30 a.m.
Edgewater Branch
6000 N. Broadway
312-742-1945 [email protected]
Master storyteller Nestor Gomez will share personal tales about the healing power of rescued animals. Nestor's new book, Rescued Me, is a collection of stories about his journey in building a new life through relationships, which includes four-legged friends. His poignant, sometimes humorous stories will resonate as they express how he found the courage to love again. His stories also reflect his experiences as an immigrant from Guatemala.
Nestor won The Moth StorySLAM, an open-mic storytelling competition, more than 90 times and is the founder of “80 Minutes Around the World, Immigration Stories.”
Copies of Rescued Me will be available for sale. A portion of each sale is donated to animal charities.
This free program is sponsored by Friends of the Edgewater Library in partnership with the Edgewater Branch

Join the Friends of the Edgewater Library and Alliance
For the Great Lakes Clean Up of Foster Beach Clean-Up

Friends of the Edgewater Library is proud to support one of our community partners, Alliance for the Great Lakes, in a beach clean-up at Foster Beach on Sunday, May 17, from 9 to 11:30 a.m.

The Great Lakes are a source of drinking water for around 40 million people, so what ends up on our beaches doesn’t just stay there. It affects marine wildlife and us Chicagoans.

All are invited to join the clean-up festivities at Foster Beach. A registration table will be at Lakeside Café Concession & Lakefront Trail.

Parking is available; entrance on Foster Avenue.
registration link: https://bit.ly/3QOS87E

National Paper Airplane Day is an unofficial observance, celebrated on May 26 each year in the United States to commemorate the simple aeronautical toy. Starting early, the Rogers Park Library on May 9, 2026, celebrated this day by folding paper airplanes to fly or to decorate with the help of Robert C. Smith, our resident Origami Master. The students made small folds on the paper airplanes to make them pitch, roll, yaw, and glide further. If you missed the May 9th session, join us on May 31, 2026, from 1:30 pm to 2:30 pm to make a sheet of paper take flight across a room or in your imagination.

Register at this link
https://chipublib.bibliocommons.com/events/69e8fb6cbd5c392c7645d856

On May 9, 2026, the Chinese Mutual Aid Association’s Youth Dance Troupe celebrated Asian American and Pacific Islander (AAPI) Heritage Month at the Rogers Park Library. We celebrate the history, culture, and contributions of people from across the Asian continent and the Pacific Islands of Melanesia, Micronesia, and Polynesia. The Lion Dance is a traditional Chinese performance. The performers mimic a lion's movements in a costume to bring good luck, prosperity, and ward off evil spirits. The Lotus Dance is a traditional, graceful performance art, notably in Vietnam and China, symbolizing purity, spiritual awakening, and beauty. With flowing costumes, the dancers depict the blossoming of a lotus flower, emerging from muddy waters to represent divine beauty.

Continue discussing Steven Pinker’s Rationality: What It Is, Why It Seems Scarce, Why It Matters, May 30, 2026, from 2:30 PM to 4:30 PM Central Standard Time using Google Meet.

On May 2, 2026, our group of four continued exploring Steven Pinker’s Rationality, and we delved into probability. We can calculate the chances of an event occurring. Suppose two black and two white marbles are mixed in an urn, and two marbles are blindly taken one at a time. There are four outcomes for any two marbles picked from the urn: A. black then black, B. black then white, C. white then black, and D. white then white. Each combination has a 25% chance of occurring. If a black marble is the first, this event eliminates combinations C and D, leaving a 50% chance for the remaining combinations A or B. If a black marble were either the first or second picked, this would eliminate combination D, leaving combinations A, B, or C, each with a ⅓ chance.

Probabilities can also be calculated for any set of events, such as being attacked by a Great White Shark or struck by lightning. We can increase the odds of these happening by changing the circumstances, such as swimming in shark-infested waters or playing golf during a lightning storm. Would choosing to swim in shark-infested waters or to play golf during a lightning storm be a rational decision?

We can further refine the odds using Bayes' theorem, a formula for calculating conditional probabilities by finding the likelihood of an event occurring based on prior knowledge related to that event. For example, what is the chance that a patient has cancer if he gets a positive test that has a 90% True Positive Rate, finding cancer in 9 out of 10 cancer patients, and if this cancer occurs at a rate of 1% in a population?

Let’s see how Bayes’ Theorem works out using a population of 1,000 people. The Population Base Rate is 1% with cancer, which gives us 10 people with cancer and leaves us with 990 people who do not have it. Since the test gives 90% True Positive results for people with cancer, which is 0.90 times 10 people with cancer, only 9 have a positive result. Out of the 990 people without cancer, the test mistakenly gives a False Positive test for 10%, which is 990 times 0.10, giving 99 healthy people a scary test result. Adding the 9 with a True Positive test with the 99 with a False Positive result, gives us a total of 108 people who get a positive test. The probability for a patient with a True Positive test result to have cancer is found by dividing 9, the number of True Positive test results, by 108, all who tested positively, giving the patient an 8.3% chance of having cancer.

Bayes’ Theorem calculates the base rate of a hypothesis with additional consideration given to prior conditions. When this problem is given to doctors, they overestimate the chances of a patient having the cancer, increasing the likelihood of unnecessary surgery, radiation, and chemotherapy. What would be a prudent next step to take?

Auto and life insurance premiums are also examples of using Base Rate logic. Actuaries calculate insurance risks using demographics to set a starting price, which makes auto insurance expensive for teenagers, but their life insurance premiums are much cheaper. Is this fair? Would it be fairer to apply the same premium for everyone?
Probability Theory goes back to the philosopher and mathematician, Blaise Pascal, who proposed a wager as an argument, treating the existence of God as a probability problem. A wise decision is to bet that God exists, since if God exists, you gain all; if God does not exist, you lose nothing. Is this the ultimate insurance policy? Is Pascal’s Wager less about the existence of God and more about Risk Management?

For that matter, is this a logical way to place a bet? Is this the way to make rational decisions? We invite you to find out more about Expected Utility in Steven Pinker’s Rationality: What It Is, Why It Seems Scarce, Why It Matters, BF441.P56 2021 on May 30, 2026, from 2:30 PM to 4:30 PM. Send a request for the meeting link, and I will send it to you. I create a new Google Meet link for each discussion. Captions are available on Google Meet. Anyone can enable closed captioning for their screen, and I will show how to turn on captions for each meeting.
I hope to see you on May 30, 2026,
Kang