7. SPEED—5000 ADDITIONS A SECOND: Moore School’s ENIAC (Electronic Numerical Integrator and Calculator) 113 8. RELIABILITY—NO WRONG RESULTS: Bell Laboratories’ General-Purpose Relay Calculator 128 9. REASONING: The Kalin-Burkhart Logical-Truth Calculator 144 10. AN EXCURSION: The Future Design of Machines That Think 167 11. THE FUTURE: Machines That Think, and What They Might Do for Men 180 12. SOCIAL CONTROL: Machines That Think, and How Society May Control Them 196 SUPPLEMENTS 1. Words and Ideas 209 2. Mathematics 214 3. References 228 INDEX 257 Chapter 1 CAN MACHINES THINK? WHAT IS A MECHANICAL BRAIN? Recently there has been a good deal of news about strange giant machines that can handle information with vast speed and skill. They calculate and they reason. Some of them are cleverer than others—able to do more kinds of problems. Some are extremely fast: one of them does 5000 additions a second for hours or days, as may be needed. Where they apply, they find answers to problems much faster and more accurately than human beings can; and so they can solve problems that a man’s life is far too short to permit him to do. That is why they were built. These machines are similar to what a brain would be if it were made of hardware and wire instead of flesh and nerves. It is therefore natural to call these machines _mechanical brains_. Also, since their powers are like those of a giant, we may call them _giant brains_. Several giant mechanical brains are now at work finding out answers never before known. Two are in Cambridge, Mass.; one is at Massachusetts Institute of Technology, and one at Harvard University. Two are in Aberdeen, Md., at the Army’s Ballistic Research Laboratories. These four machines were finished in the period 1942 to 1946 and are described in later chapters of this book. More giant brains are being constructed. Can we say that these machines really think? What do we mean by thinking, and how does the human brain think? HUMAN THINKING We do not know very much about the physical process of thinking in the human brain. If you ask a scientist how flesh and blood in a human brain can think, he will talk to you a little about nerves and about electrical and chemical changes, but he will not be able to tell you very much about how we add 2 and 3 and make 5. What men know about the way in which a human brain thinks can be put down in a few pages, and what men do not know would fill many libraries.