QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL Qual. Reliab. Engng. Int. 2009; 25:759–769 Published online 6 May 2009 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/qre.1028 Research The Cheshire Cat on Engineering Design ‡ George A. Hazelrigg ∗, † National Science Foundation, Arlington, VA, U.S.A. In Lewis Carroll’s Alice in Wonderland, the Cheshire Cat provides to Alice the underlying tenets of modern normative decision theory. These tenets are clear and simple. Yet few engineers have grasped their significance, and many design methods in common practice violate them with potentially devastating conse- quences. This paper reviews the advice given to Alice by the Cheshire Cat and places it in the context of engineering design. It goes on to discuss the contri- butions of von Neumann and Morgenstern as they add to the Cat’s advice. Published in 2009 by John Wiley & Sons, Ltd. KEY WORDS: engineering design; decision theory INTRODUCTION C harles Lutwidge Dodgson was born the son of a clergyman in Daresbury, England, on January 27, 1832. He attended Rugby School and graduated from Christ Church College Oxford in 1854, where he remained lecturing on mathematics until 1881. Dodgson is the author of several mathematics books, including A Syllabus of Plane Algebraical Geometry (1860) and Euclid and His Modern Rivals (1879). He is best known, however, for the books that he wrote under the pen name Lewis Carroll, Alice’s Adventures in Wonderland (1865) and Through the Looking Glass (1872). He clearly had a passion for logic, and this shows not only in his technical works, but in his fictional writings as well. A notable quote may be found in Through the Looking Glass: ‘Contrariwise’ said Tweedledee, ‘If it was so, it might be; and if it were so, it would be, but as it isn’t, it ain’t. That’s logic.’ In Alice’s Adventures in Wonderland, commonly referred to as Alice in Wonderland 1 , Dodgson presents the fundamental principles of modern, normative decision theory. Alice, walking a path through the Wonderland forest, comes to a fork. Not knowing which way to go, she stands pondering about the decision she must make when the Cheshire Cat appears in the tree above her. Alice asks the Cat which alternative she should choose. But rather than answer her question, the Cat instead provides Alice with advice applicable to decision making in all decision situations. The advice is provided with a precision typical of an accomplished mathematician (Figure 1). ∗ Correspondence to: George A. Hazelrigg, National Science Foundation, Arlington, VA, U.S.A. † E-mail: ghazelri@nsf.gov ‡ The views expressed in this article are strictly those of the author and do not necessarily reflect the views of the National Science Foundation or the Federal Government. This article is a U.S. Government work and is in the public domain in the U.S.A. Published in 2009 by John Wiley & Sons, Ltd.