# The Art of Logic in an Illogical World

**How both logical and emotional reasoning can help us live better in our post-truth world**

In a world where fake news stories change election outcomes, has rationality become futile? In

*The Art of Logic in an Illogical World,*Eugenia Cheng throws a lifeline to readers drowning in the illogic of contemporary life. Cheng is a mathematician, so she knows how to make an airtight argument. But even for her, logic sometimes falls prey to emotion, which is why she still fears flying and eats more cookies than she should. If a mathematician can’t be logical, what are we to do? In

*this book*

*,*Cheng reveals the inner workings and limitations of logic, and explains why alogic–for example, emotion–is vital to how we think and communicate. Cheng shows us how to use logic and alogic together to navigate a world awash in bigotry, mansplaining, and manipulative memes. Insightful, useful, and funny, this

*essential book is for anyone who wants to think more clearly.*

## Praise

**PRAISE FOR BEYOND**

INFINITY:

"Ms. Cheng's chatty tone keeps things fresh. She has a

knack for folksy analogies, and at different points in the book she illuminates

different properties of infinity by discussing Legos, the iPod Shuffle,

snorkeling, Battenberg cakes and Winnie-the-Pooh... she does a great service by

showing us non-mathematician schlubs how real mathematical creativity works."—*Wall Street Journal*

"Our minds cannot truly grasp the concept of infinity, but Eugenia

Chang takes us on a wild journey to help us in our search for it. It's a small,

unassuming symbol-8-but it holds a giant idea. Cheng helps us understand the

basics of infinity and then takes us on a ride to see its most lofty

applications. From the practical to the entirely theoretical, this is a book to

watch for."—*Paste Magazine
*

"Unique to this text is the friendly and conversational style with

which the author communicates her passion for mathematics. Cheng succeeds in

offering a taste of creativity in mathematics research, reminding the reader

that mathematics is fun because 'you can have anything that you can think of.

The only caveat is that you have to take all the logical consequences of your

new toy as well'. Her passion for research is unassuming and adds a humanistic

sensitivity to the book's central quest."—*Mathematics Teacher
*

"[A] superb study of the mathematics of infinity... Acknowledging the

difficulties the proofs present, Cheng wisely provides readers with reasonably

accessible equations, useful graphics, and entertaining and straightforward

explanations... [Her] enthusiasm for mathematics is infectious and readers

curious about the mathematics of infinity will find her to be a worthy guide."—*Publishers Weekly*

"*Beyond Infinity *is witty, charming, and crystal clear. . Eugenia Cheng's enthusiasm and carefully chosen metaphors and analogies carry us effortlessly through the mathematical landscape of the infinite. A brilliant book."—*Ian Stewart, author of Calculating the Cosmos*

"The idea of infinity is one of the most perplexing things in mathematics, and the most fun. Eugenia Cheng's *Beyond Infinity* is a spirited and friendly guide--appealingly down to earth about math that's extremely far out."

—*Jordan Ellenberg, author of How Not to Be Wrong and professor of mathematics at University of Wisconsin-Madison*

**PRAISE FOR HOW TO BAKE**

PI:

"Cheng never quite overeggs her metaphor of the mathematician as

chef...and her tone is clear, clever and friendly. Even at her most whimsical

she is rigorous and insightful. Potentially confusing ideas are expressed with

a matter-of-fact simplicity.... *How to Bake Pi*

is a welcome addition to the popular-math shelf, unusual not only because of

its quirky premise but also because Cheng is a woman, a lucid and nimble

expositor, and unashamedly proud of her domestic obsessions.... It would be

wonderful if this book attracted a new audience to the field. And there's no

better ambassador (or dinner-party host, I'd wager) than Eugenia Cheng."—*Alex Bellos, New York Times Book Review*

"Invoking plenty of examples from cooking and baking, as well as other

everyday-life situations such as calculating a taxi fare, searching for love

through online dating services and training for a marathon, [Cheng] explains

abstract mathematical ideas-including topology and logic-in understandable

ways.... Her lively, accessible book demonstrates how important and intriguing

such a pursuit can be."—*Scientific American*

"[A] funny and engaging new book."—*Simon Worrall, National Geographic News*

"[Cheng's] book, a very gentle introduction to the main ideas of

mathematics in general and category theory in particular, exudes enthusiasm for

mathematics, teaching, and creative recipes. Category theory is dangerously

abstract, but Cheng's writing is down-to-earth and friendly. She's the kind of

person you'd want to talk to at a party, whether about math, food, music, or

just the weather.... Cheng's cheerful, accessible writing and colorful examples

make *How to Bake Pi *an

entertaining introduction to the fundamentals of abstract mathematical

thinking."—*Evelyn Lamb, Scientific American's "Roots of Unity" blog*

"[A] slyly illuminating dispatch on the deep meaning of mathematics....

Cheng manages to do for us what the mathematician Keith Devlin has said

mathematicians do for themselves: she compels us to see numbers and symbols as

vivid characters in an ongoing drama, a narrative in which we are alternately

observers and participants."—*Natalie Angier, The American Scholar*

"[Cheng] masterfully describes what

mathematics is. This includes careful and motivated descriptions of the ideas

and methods of abstractions, generalization, logic, and axiomatization.... This

book is entertaining, insightful, deep and accessible."—*Mathematical Reviews*

"Why go to all the trouble to write a book

to help people understand mathematics? Because, as Cheng observes,

'understanding is power, and if you help someone understand something, you're

giving them power.' Read *How to Bake Pi*

and you will, indeed, go away feeling empowered."—*Marc Merlin, Medium*

"[O]ften entertaining...frequently illuminating.... [*How to Bake Pi*] offers enough nourishment for the brain to

chew on for a long time."—*Columbus Dispatch*

"This is the best book imaginable to introduce someone who doesn't

think they are interested in mathematics at all to some of the deep ideas of

category theory, especially if they like to bake."—*MAA Reviews*

"In her new book, *How to Bake Pi*,

mathematician/baker Eugenia Cheng offers a novel, mathematical approach to

cooking.... *How to Bake Pi* is more than a

mathematically-minded cookbook. It is just as much a book about mathematical

theory and how we learn it. The premise at the heart of the book is that the

problem that stops a cookbook from teaching us how to cook is the same problem

that makes math classes so bad at actually teaching us to do math."—*Ria Misra, io9*

"Through an enthusiasm for cooking and zest for life, the author, a

math professor, provides a new way to think about a field we thought we knew."—*Chemical Engineering Progress*

"Combined with infectious enthusiasm for cooking and a zest for life,

Cheng's perspective on math becomes this singular book: a funny, lively, and

clear journey no popular book on math has explored before. *How to Bake
Pi*...will dazzle, amuse, and enlighten."—

*Gambit Weekly*"Beginning each

chapter with a recipe, Cheng converts the making of lasagna, pudding, cookies,

and other comestibles into analogies illuminating the mathematical enterprise.

Though these culinary analogies teach readers about particular mathematical

principles and processes, they ultimately point toward the fundamental

character of mathematics as a system of logic, a system presenting daunting

difficulties yet offering rare power to make life easier. Despite her zeal for

mathematical logic, Cheng recognizes that such logic begins in faith -

irrational faith - and ultimately requires poetry and art to complement its

findings. A singular humanization of the mathematical project."—*Booklist*, starred review

"Cheng is exceptional at translating the

abstract concepts of mathematics into ordinary language, a strength aided by a

writing style that showcases the workings of her curious, sometimes whimsical

mind. This combination allows her to demystify how mathematicians think and

work, and makes her love for mathematics contagious."—*Publishers Weekly*, starred review

"An original book using recipes to explain sophisticated math concepts

to students and even the math-phobic.... [Cheng] is a gifted teacher... A

sharp, witty book to press on students and even the teachers of math teachers."—*Kirkus Reviews*

"[A] well-written,

easy-to-read book."—*Library Journal*

"Quirky recipes, personal anecdotes and a large dollop of equations are

the key ingredients in this alternative guide to maths and the scientific

process. You should find it as easy as cooking a pie."

—*The Observer, Tech Monthly *(UK)

"[D]eliciously lively.... It is Cheng's delightful descriptions of her

gastronomic adventures that bring the mathematics to life.... If [the book]

doesn't succeed in exciting you about mathematics, it will certainly change the

way you approach baking."—*Times Higher Education *(UK)

"Many consider maths a difficult and dry subject. But the baking-based

analogies and fun tangents used to demonstrate the various ideas in the book

are entertaining and diminish the mental gymnastics that abstract maths can

require."—*BBC Focus *(UK)

"Eugenia Cheng offers an entertaining introduction to the beauty of

mathematics by drawing on insights from the kitchen. She explains why baking a

flourless cake is like geometry and offers puzzles to whet the appetites of

maths fans."—*Times Educational Supplement *(UK)

"A curious cookbook for

the mathematical omnivore."—*The Irish Times *(Ireland)

—*The Aperiodical *(UK)

—*Leila Schneps, Professor of Mathematics at the Institut de Mathématiques de Jussieu of Pierre and Marie Curie University, and author of Math on Trial*

*How to Bake Pi*, you might be, too."

—*Jordan Ellenberg, Professor of Mathematics, University of Wisconsin-Madison, and author of How Not to Be Wrong*

*How to Bake Pi*is a real treat."

—*Steven Strogatz, Professor of Mathematics, Cornell University and author of The Joy of x*

*How to Bake Pi*, you won't look at math (nor porridge!) in the same way ever again."

—*Roberto Trotta, Astrophysicist, Imperial College London and author of The Edge of the Sky*

—*Melissa A. Wilson Sayres, Assistant Professor in the School of Life Sciences and the Biodesign Institute, Arizona State University and writer of the mathbionerd.blogspot.com blog*

—*John Baez, Professor of Mathematics at the University of California, Riverside*

—*Ian Stewart, Emeritus Professor of Mathematics at the University of Warwick, and author of Visions of Infinity and Professor Stewart's Incredible Numbers*