Walter Harry Pitts, Jr. (April 23, 1923 – May 14, 1969) was an American logician who worked in the field of computational neuroscience.Smalheiser, Neil R
"Walter Pitts"
, ''Perspectives in Biology and Medicine'', Volume 43, Number 2, Winter 2000, pp. 217–226, The Johns Hopkins University Press He proposed landmark theoretical formulations of neural activity and generative processes that influenced diverse fields such as

cognitive sciences Cognitive science is the interdisciplinary, scientific study of the mind and its processes. It examines the nature, the tasks, and the functions of cognition (in a broad sense). Mental faculties of concern to cognitive scientists include percep ...

and

psychology Psychology is the scientific study of mind and behavior. Its subject matter includes the behavior of humans and nonhumans, both consciousness, conscious and Unconscious mind, unconscious phenomena, and mental processes such as thoughts, feel ...

philosophy Philosophy ('love of wisdom' in Ancient Greek) is a systematic study of general and fundamental questions concerning topics like existence, reason, knowledge, Value (ethics and social sciences), value, mind, and language. It is a rational an ...

neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions, and its disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, ...

computer science Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, ...

artificial neural network In machine learning, a neural network (also artificial neural network or neural net, abbreviated ANN or NN) is a computational model inspired by the structure and functions of biological neural networks. A neural network consists of connected ...

s, cybernetics and

artificial intelligence Artificial intelligence (AI) is the capability of computer, computational systems to perform tasks typically associated with human intelligence, such as learning, reasoning, problem-solving, perception, and decision-making. It is a field of re ...

, together with what has come to be known as the generative sciences. He is best remembered for having written along with Warren Sturgis McCulloch, a seminal paper in scientific history, titled '' A Logical Calculus of Ideas Immanent in Nervous Activity'' (1943). This paper proposed the first mathematical model of a

neural network A neural network is a group of interconnected units called neurons that send signals to one another. Neurons can be either biological cells or signal pathways. While individual neurons are simple, many of them together in a network can perfor ...

. The unit of this model, a simple formalized neuron, is still the standard of reference in the field of neural networks. It is often called a McCulloch–Pitts neuron. Prior to that paper, he formalized his ideas regarding the fundamental steps to building a

Turing machine A Turing machine is a mathematical model of computation describing an abstract machine that manipulates symbols on a strip of tape according to a table of rules. Despite the model's simplicity, it is capable of implementing any computer algori ...

in "The Bulletin of Mathematical Biophysics" in an essay titled "Some observations on the simple neuron circuit".

Early life

Walter Pitts was born in

Detroit Detroit ( , ) is the List of municipalities in Michigan, most populous city in the U.S. state of Michigan. It is situated on the bank of the Detroit River across from Windsor, Ontario. It had a population of 639,111 at the 2020 United State ...

Michigan Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...

on April 23, 1923, the son of Walter and Marie (née Welsia). An autodidact, he taught himself

logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the study of deductively valid inferences or logical truths. It examines how conclusions follow from premises based on the structure o ...

and

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

as a child and became a proficient reader in several languages, including Greek and

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

. He is widely remembered for having spent three days in a library, at the age of 12, reading ''

Principia Mathematica The ''Principia Mathematica'' (often abbreviated ''PM'') is a three-volume work on the foundations of mathematics written by the mathematician–philosophers Alfred North Whitehead and Bertrand Russell and published in 1910, 1912, and 1 ...

'' and sent a letter to

Bertrand Russell Bertrand Arthur William Russell, 3rd Earl Russell, (18 May 1872 – 2 February 1970) was a British philosopher, logician, mathematician, and public intellectual. He had influence on mathematics, logic, set theory, and various areas of analytic ...

pointing out what he considered serious problems with the first half of the first volume. Russell was appreciative and invited him to study at

Cambridge University The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...

at age 12. The offer was not taken up; however, Pitts did decide to become a logician. At age 15 he left home to study.

Academic career

Pitts probably continued to correspond with Bertrand Russell; and at the age of 15 he attended Russell's lectures at the

University of Chicago The University of Chicago (UChicago, Chicago, or UChi) is a Private university, private research university in Chicago, Illinois, United States. Its main campus is in the Hyde Park, Chicago, Hyde Park neighborhood on Chicago's South Side, Chic ...

.Cf. Anderson (1998
p.218
conversation with Michael A. Arbib He stayed there, without registering as a student. While there, in 1938 he met Jerome Lettvin, a pre-medical student, and the two became close friends.Cf. Conway, Flo; Siegelman, Jim (2005)
p.138
/ref> Russell was a visiting professor at the University of Chicago in the fall of 1938, and he directed Pitts to study with the logician

Rudolf Carnap Rudolf Carnap (; ; 18 May 1891 – 14 September 1970) was a German-language philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism. ...

. Pitts met Carnap at Chicago by walking into his office during office hours, and presenting him with an annotated version of Carnap's recent book on logic, ''The Logical Syntax of Language''. Since Pitts did not introduce himself, Carnap spent months searching for him, and, when he found him, he obtained for him a menial job at the university and had Pitts study with him. Pitts at the time was homeless and without income. He mastered Carnap's abstract logic, then met with and was intrigued by the work of the Ukrainian mathematical physicist Nicolas Rashevsky, who was also at Chicago and was the founder of mathematical biophysics, remodeling biology on the structure of the physical sciences and

mathematical logic Mathematical logic is the study of Logic#Formal logic, formal logic within mathematics. Major subareas include model theory, proof theory, set theory, and recursion theory (also known as computability theory). Research in mathematical logic com ...

.Cf. Conway, Flo; Siegelman, Jim (2005)
p.139
/ref> Pitts also worked closely with the mathematician Alston Scott Householder, who was a member of Rashevsky's group. During his studies under Carnap, Pitts was also a regular attendant at Nicolas Rashevsky’s seminars in theoretical biology, which included Frank Offner, Herbert Landahl, Alston Householder, and the neuroanatomist Gerhardt von Bonin from the University of Illinois at Chicago. In 1940, Von Bonin introduced Lettvin to Warren McCulloch, who would become a professor of psychiatry at Illinois. In 1941 Warren McCulloch took a position as professor of psychiatry at the University of Illinois at Chicago, and in early 1942 he invited Pitts, who was still homeless, together with Lettvin to live with his family. In the evenings, McCulloch and Pitts collaborated. Pitts was familiar with the work of

Gottfried Leibniz Gottfried Wilhelm Leibniz (or Leibnitz; – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat who is credited, alongside Isaac Newton, Sir Isaac Newton, with the creation of calculus in ad ...

on computing and they considered the question of whether the nervous system could be considered a kind of universal computing device as described by Leibniz. This led to their seminal

s paper "A Logical Calculus of Ideas Immanent in Nervous Activity". After five years of unofficial studies, the University of Chicago awarded Pitts an

Associate of Arts An associate degree or associate's degree is an undergraduate degree awarded after a course of post-secondary study lasting two to three years. It is a level of academic qualification above a high school diploma and below a bachelor's degree ...

(his only earned degree) for his work on the paper. In 1943, Lettvin introduced Pitts to

Norbert Wiener Norbert Wiener (November 26, 1894 – March 18, 1964) was an American computer scientist, mathematician, and philosopher. He became a professor of mathematics at the Massachusetts Institute of Technology ( MIT). A child prodigy, Wiener late ...

at the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...

. Their first meeting, where they discussed Wiener's proof of the ergodic theorem, went so well that Pitts moved to

Greater Boston Greater Boston is the metropolitan region of New England encompassing the municipality of Boston, the capital of the U.S. state of Massachusetts and the most populous city in New England, and its surrounding areas, home to 4,941,632. The most s ...

to work with Wiener. While Pitts was an unofficial student under the aegis of Wiener at MIT until their acrimonious parting in 1952, he formally enrolled as a graduate student in the

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

department during the 1943–1944 academic year and in the

electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the l ...

department from 1956–1958. In 1944, Pitts was hired by Kellex Corporation (later acquired in 1950 by Vitro Corporation) in New York City, part of the Atomic Energy Project. From 1946, Pitts was a core member of the Macy conferences, whose principal purpose was to set the foundations for a general science of the workings of the human mind.

Personal life, emotional trauma and decline

In 1951, Wiener convinced Jerome Wiesner to hire some physiologists of the nervous system. A group was established with Pitts, Lettvin, McCulloch, and Pat Wall. Pitts wrote a large dissertation on the properties of neural nets connected in three dimensions. Lettvin described him as "in no uncertain sense the genius of the group … when you asked him a question, you would get back a whole textbook." Pitts never married. Pitts was also described as an eccentric, refusing to allow his name to be made publicly available. He continued to refuse all offers of advanced degrees or positions of authority at MIT, in part as he would have to sign his name. In 1952, Wiener suddenly turned against McCulloch—his wife, Margaret Wiener, hated McCulloch—and broke off relations with anyone connected to him, including Pitts. Although he remained employed as a research associate in the Research Laboratory of Electronics at MIT "as little more than a technicality" for the rest of his life, Pitts became increasingly socially isolated. In 1959, the paradigmatic "What the Frog’s Eye Tells the Frog’s Brain" (credited to Humberto Maturana, Lettvin, McCulloch and Pitts) conclusively demonstrated that "analog processes in the eye were doing at least part of the interpretive work" in image processing as opposed to "the brain computing information digital neuron by digital neuron using the exacting implement of mathematical logic", leading Pitts to burn his unpublished doctoral dissertation on probabilistic three-dimensional neural networks and years of unpublished research. He took little further interest in work, excepting only a collaboration with Lettvin and Robert Gesteland which produced a paper on

olfaction The sense of smell, or olfaction, is the special sense through which smells (or odors) are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste. In humans, ...

in 1965. Pitts died in 1969 of bleeding esophageal varices, a condition usually associated with

cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, chronic liver failure or chronic hepatic failure and end-stage liver disease, is a chronic condition of the liver in which the normal functioning tissue, or parenchyma, is replaced ...

and

alcoholism Alcoholism is the continued drinking of alcohol despite it causing problems. Some definitions require evidence of dependence and withdrawal. Problematic use of alcohol has been mentioned in the earliest historical records. The World He ...

Publications

* Walter Pitts
"Some observations on the simple neuron circuit"
'' Bulletin of Mathematical Biology'', Volume 4, Number 3, 121–129, 1942. * Warren McCulloch and Walter Pitts, "A Logical Calculus of Ideas Immanent in Nervous Activity", 1943, '' Bulletin of Mathematical Biophysics'' 5:115–133. Reprinted in ''Neurocomputing: Foundations of Research''. Edited by James A. Anderson and Edward Rosenfeld. MIT Press, 1988
pages 15–27
* Warren McCulloch and Walter Pitts, "On how we know universals: The perception of auditory and visual forms", 1947, ''Bulletin of Mathematical Biophysics'' 9:127–147. * R. Howland, Jerome Lettvin, Warren McCulloch, Walter Pitts, and P. D. Wall, "Reflex inhibition by dorsal root interaction", 1955, ''Journal of Neurophysiology'' 18:1–17. * P. D. Wall, Warren McCulloch, Jerome Lettvin and Walter Pitts, "Effects of strychnine with special reference to spinal afferent fibres", 1955, ''Epilepsia Series'' 3, 4:29–40. * Jerome Lettvin, Humberto Maturana, Warren McCulloch, and Walter Pitts, "What the Frog's Eye Tells the Frog's Brain", 1959, ''Proceedings of the Institute of Radio Engineers'' 47: 1940–1951. * Humberto Maturana, Jerome Lettvin, Warren McCulloch, and Walter Pitts, "Anatomy and physiology of vision in the frog", 1960, ''Journal of General Physiology'', 43:129—175. * Robert Gesteland, Jerome Lettvin and Walter Pitts, "Chemical Transmission in the Nose of the Frog", 1965, ''J.Physiol''. 181, 525–529.

References

External links

website of Professor Charles Wallis, Department of Cognitive Science, California State University at Long Beach, accessed 30 Jan. 2009 (archived 2009)
"The Man who Tried to Redeem the World with Logic"
''Nautilus Magazine'' issue 21, 5 February 2015 {{DEFAULTSORT:Pitts, Walter 1923 births 1969 deaths American logicians 20th-century American psychologists American cognitive neuroscientists Philosophers from Michigan Massachusetts Institute of Technology alumni University of Chicago alumni