simon_baron_cohen's picture
Professor of Developmental Psychopathology, University of Cambridge; Fellow, Trinity College, Cambridge; Director, Autism Research Centre, Cambridge; Author, The Pattern Seekers
Boolean Logic

George Boole, the son of a shoemaker, left school at sixteen, and ended up a Professor of Mathematics at Queens College in Cork in Ireland. As the only breadwinner in his family, he became a teacher at age sixteen, opened his own school in Lincoln in England by age nineteen, and fifteen years later was a mathematician and philosopher of logic. Why did Google celebrate his 200th birthday on the 2nd November 2015? And why should we remember his contributions?

In 1854 he wrote a book called An Investigation of the Laws of Thought which distilled the essence of logical thought down to terms like AND (e.g., x AND y), OR (e.g., x OR y), and NOT (e.g., NOT x), or combinations of these. This took Aristotelian logic (the syllogism, expressed in words) and insisted these be formulated as equations, which was a revolutionary step. Equally important, Boolean logic is today seen as the foundations of the "information age," or what we also call the "computer age." This is because each "value" in these logical statements or equations reduces down to either being true or false, with zero ambiguity. The logic is binary. No wonder they could be applied, more than a century later, in the design of electronic circuits in computers.

For me, the importance of Boolean logic even goes beyond its contribution to the logic of computers. Each of his terms is an "operation," like the familiar mathematical ones of addition and multiplication. These terms describe what happens if you take something as input, and perform an operation on it. You end up with an output. This is at the core of what I call "systemizing": take input, perform an operation, and observe the output. Boole, without realizing it, was describing how the human mind systemizes. In this way, he anticipated how to describe a uniquely human aspect of cognition, one that enables humans to do engineering (designing a system) and to innovate (changing a system).

Consider a much discussed example: Vinton Cerf, co-inventor of the Internet, was pouring peppercorns into a funnel and found if he dropped handfuls of peppercorns into it, the funnel got blocked or congested. Nothing came out. But if he poured the peppercorns in one a time, they didn’t get stuck, they flowed out smoothly. In system 1, the input is a handful of peppercorns, the operation is pouring them into a funnel, and the output is disappointingly nothing! In system 2, the input is one-peppercorn-at-a-time, the operation remains the same, but now the output is a pleasing flow of peppercorns. There are lessons here for how we as humans design not just pepper grinders, but also traffic systems (that either cause or avoid congestion), or how we design the post office, to cope with a volume of letters. Indeed, Boolean logic allows us to describe not just how an engineer designs any system, but how we humans systemize.

Here’s just one more legacy of Boolean logic. We know that people with autism have very logical minds, and have a strong drive to systemize. If we can generalize, they have a preference for information that can be systemized (such as factual information, or repeating, lawful patterns of information that doesn’t change unlawfully). They don’t cope well with information that is hard to systemize, because it contains ambiguity, or because it changes unexpectedly (such as social interaction, where what people do or say is rarely the same, except in highly ritualized contexts). Our modern understanding of autism as a hyper-systemizing mind owes a huge debt to Boolean logic that enables us to characterize the beauty and the extraordinary power of binary thinking, and also where such thinking is best used.