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C The Rise of Worse Is Better By Richard P. Gabriel The key problem with Lisp today stems from the tension between two opposing software philosophies. The two philosophies are called “The Right Thing” and “Worse Is Better.”1 I, and just about every designer of Common Lisp and CLOS, have had extreme exposure to the MIT/Stanford style of design. The essence of this style can be captured by the phrase “the right thing.” To such a designer it is important to get all of the following characteristics right: • Simplicity—the design must be simple, both in implementation and interface. It is more important for the interface to be simple than that the implementation be simple. • Correctness—the design must be correct in all observable aspects. Incorrectness is simply not allowed. • Consistency—the design must not be inconsistent. A design is allowed to be slightly less simple and less complete to avoid incon- sistency. Consistency is as important as correctness. 1This is an excerpt from a much larger article, “Lisp: Good News, Bad News, How to Win Big,” by Richard P. Gabriel, which originally appeared in the April 1991 issue of AI Expert magazine. © 1991 Richard P. Gabriel. Permission to reprint granted by the author and AI Expert.