AI HISTORY/PRIMARY SOURCES × PYTHON

All History of AI

From the dream of thinking machines to AI that writes. Nearly 400 years of challenges, to touch, run and check for yourself

We went back to the original sources on AI, such as papers, books and articles from the time, and opened 667 of them one by one. Then we implemented how the ideas work in 146 programs.

Behind the one line in a textbook lies a real story that is thrilling. For the famous stories, we went back to the speaker's own book, paper or article from the time and checked.
You can check how things work with your own hands: move the figures and run Python. Start from any chapter.

01Chapter 01 · Overview

Waves of Booms and How They Got Numbered

Who numbered the “first to fourth AI booms”, and when?

AI has gone through periods of rising hopes (booms) and falling hopes (winters) many times. But the size of a boom cannot be seen. So this site counted, year by year, how often certain words were used in English books, in the titles of papers worldwide and of Japanese books, and in remarks in Japan's National Diet, and looked at the shape of the waves.

The figure on the right shows that real data. Diet remarks that use “AI” to mean AI formed a peak in 2019, dropped, and in 2023 rose above the earlier peak. But the shape changes with how you count. Searching for the two letters “AI” also catches words likeAIDSandAIG. So we looked at the hits one by one, made a standard, and counted again.

The numbering “first to fourth” is the way of counting commonly used in Japan. In English books, it is not the booms but the that gets numbered. In the Diet in 1985, it was explained as (translated).

What you think you knowThe popular story:The was a term Minsky and Schank warned of
The original source says:In the record of the 1984 panel, Minsky is not among the panelists. The words appeared as the name of the worst outcome that might be coming.
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What the figure shows:The shape and size of a boom change with the way it is counted. Numbering booms from 1 to 4 is mainly a Japanese practice; English accounts tend to number the winters instead.

02Chapter 02 · Up to 1955

Thinking Machines, Computing Machines

Since when has been asked in earnest?

In 1637, Descartes described two ways to tell a human-like machine from a real person. The “chess-playing machine” of 1770 had a person hidden inside. In 1843, Ada Lovelace wrote notes on the Analytical Engine. In Edo-period Japan, mechanical karakuri dolls were built.

In 1936, Alan Turing presented the idea of a machine that computes with just a tape and a table of rules. Open the lid of the 1936 box in the figure on the right to see that machine adding 1 to a binary number. The head reads a symbol on the tape, looks it up in the table, rewrites it, and moves one step left or right. He argued that any computation can be written as a combination of these simple moves.

In 1943, Warren McCulloch and Walter Pitts described the brain's nerve cells (neurons) as switches. A neuron adds up its inputs and fires once the total reaches or exceeds a set value. This is the starting point of neural networks. Then in 1950, Turing replaced the question with an imitation game.

What you think you knowThe popular story:Pass if you fool 30% of the judges
The original source says:That standard is not in Turing's paper. What he wrote was a forecast about 50 years ahead.
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What the figure shows:The question “Can machines think?” did not suddenly appear in 1950: for over 300 years after Descartes wrote in 1637 about ways to tell human-like machines from people, people built and imagined machines that seemed to think, using dolls, gears, cards, tapes, and switches, but inside were hidden people or fixed procedures such as tables, gears, cards, rule tables, and switches. In 1950, Turing stopped asking about their inner workings and proposed the imitation game: could a machine be identified through written exchanges alone?

03Chapter 03 · 1955–1960

Gets Its Name

A machine that corrects itself when it errs: what did it learn?

In 1955, the proposal for a summer workshop used the name . What the proposal held was not a plan to finish the job in one summer but an expectation that significant progress could be made on one or more problems.

In 1958, the US Navy showed Frank Rosenblatt's perceptron to reporters. After about 50 trials, it could tell whether a mark on a card was on the right or the left. Try showing it cards in the figure on the right. Only when it errs does it correct the weights of the squares where the mark was. Look at the weight pattern at the end, and you can see that the machine knows no words like “right” or “left”; it only learned which squares vote for which side.

Around the same time, Herbert Simon and Allen Newell made predictions such as “a digital computer will be the world's chess champion within 10 years” (translated), and even wrote down the day the answers would be checked.

What you think you knowThe popular story:The Dartmouth people meant to finish AI in a single summer
The original source says:What the proposal held was an expectation of significant progress on one or more problems.
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What the figure shows:Without knowing the words “right” and “left,” the perceptron only adjusted its weights when it was wrong, learning which side each square should vote for. Even after about 50 cards, its weight board contains only the combined effect of the cards it got wrong.

Errors per 5 cards
04Chapter 04 · The 1960s

Search, Reasoning and a Big Prediction

How should we search a maze to find the exit fast?

The first AI was good at solving problems with clear rules, like mazes and puzzles, by searching. A* (1968) picks the next place to check by adding the estimated distance to the goal to the distance traveled so far. In the figure on the right, compare searches with no estimate, with A*, and with the estimate tripled. With a good estimate, the shortest route is found with little searching. If the estimate is made too large, the search is fast but no longer finds the shortest route.

ELIZA (1966) only spotted keywords and rearranged sentences by rules, yet it seemed to be talking with a person. In 1968 in Japan, a machine that read postal codes was shown to the public.

Big predictions came too. In 1965, Simon wrote that a person can do.

What you think you knowThe popular story:Simon predicted that in 20 years machines would take all human jobs
The original source says:The original paper went on to say this was a forecast of technical ability and said nothing about how machines would be used.
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What the figure shows:Adding an estimate of the remaining distance to the goal finds the shortest route while checking fewer squares, but an estimate that is too large checks even fewer squares at the cost of the shortest route. Moving just 1 estimate slider lets readers feel where that gain turns into a loss.

05Chapter 05 · 1966–1980

The Winter After the First Boom

Did the come in the same year in the US, the UK and Japan?

This is the time said to have brought an , when results fell short of hopes and research funding shrank. The 1966 US report on machine translation, the 1969 book and the 1973 Lighthill report in the UK followed one another.

But line up the events of the three countries in the figure on the right, and the winter did not arrive in step. In Japan, the national project “Pattern Information Processing System” began in 1971. Neural network research that leads to today's AI was also born: the Associatron in 1972 (recalling the whole from a part), the Neocognitron in 1979 (recognizing shapes even when shifted in position), and more. Move “Current year”, and even for the same year, sources give different answers: , or “there was no winter”.

This chapter runs 19 mechanisms, including the wall a single straight line cannot cross (XOR), the combinatorial explosion, beam search for spoken language, DP matching that evens out the speed of a voice, and a way to find the parts of a face.

What you think you knowThe popular story:1974–1980 was an AI winter, and research stopped
The original source says:The membership of ACM's AI special interest group nearly tripled from 1973 to 1978. Whether it was an depends on what you use as the yardstick.
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What the figure shows:The dates of an AI winter vary greatly depending on which source is used as a guide. In Japan, major projects and neural network research were starting around the same time.

06Chapter 06 · 1975–1990

Writing In the Knowledge of Experts

Line up rules: what can they do, and what can't they?

The second boom began with AI that writes experts' knowledge in as rules (expert systems). MYCIN, from 1972, was research on advising which drug to choose for an infection. It combined rules with certainty factors (how likely something is), and when asked “Why?”, it answered by showing the rules it had used.

The figure on the right runs the same mechanism on a bicycle's condition (it gives no medical advice). Press the known facts to switch them, and usable rules fire one after another, changing the conclusion and its certainty. For a symptom with no rule, it can answer nothing. The effort of writing in more knowledge became the limit of this method.

In 1987 in Japan, the Sendai subway began running with fuzzy control, which mixes in vague rules.

What you think you knowThe popular story:The second boom went too far because of researchers' big promises
The original source says:A 1984 article said most researchers came to talk about small steps of progress, and it was some of the companies with exhibits that acted as if the dream had already come true.
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What the figure shows:Rules work one after another from known facts to reach a conclusion and can explain their reasons. But they cannot answer anything their rules do not cover.

07Chapter 07 · 1979–1995

Japan's Fifth Generation Computer

What did the national project aim at, and what did it leave behind?

In 1982, Japan began a plan for a new kind of computer centered on reasoning and knowledge processing. It was named , coming after the generations of parts (vacuum tubes, transistors, ICs and LSIs). The world reacted, and the UK and the US also began big projects.

The central tool was Prolog, a logic programming language. You line up facts and rules, and it answers questions by reasoning. In the figure on the right, find “grandparent” and “cousin” from family facts. The number of fact lookups is the effort of reasoning. In 1992, the parallel inference machine PIM/p could make 156 million inferences per second.

In the final evaluation, the target for reasoning speed was beaten, but a mechanism for conversing with people was never built. Whether it was a depends on what you take as the goal.

What you think you knowThe popular story:The Fifth Generation failed
The original source says:The final evaluation wrote that it (translated). Judgments differ depending on what you take as the goal.
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What the figure shows:With facts and rules in place, reasoning can answer questions. But the more distant the relatives, the more work it takes to check the facts.

08Chapter 08 · 1987–2005

Winter, and Sprouts Growing Quietly

How does a network with stacked layers learn?

The expert-system business slowed, and the second AI winter came. Meanwhile, technology that learns from data was quietly growing. In 1986, Nature published a paper on training multilayer neural networks with backpropagation.

The figure on the right shows a network with a hidden layer learning XOR. The error at the output is passed from the back layers to the front ones, and the weights are corrected little by little. XOR, which one layer could not learn, can be solved by stacking layers. In the graph below, the error goes down.

Around the same time came the network that can remember a long context (LSTM, 1997), the support vector machine that draws the widest road between groups of data (1995), and backgammon that learns by playing itself (1992).

What you think you knowThe popular story:Hinton invented backpropagation
The original source says:Other researchers had independently discovered it before the 1986 paper. In Japan, Shun'ichi Amari also published a theory in 1967 of learning by correcting errors little by little.
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What the figure shows:A boundary for XOR that 1 layer could not draw gradually becomes possible by adding layers and passing errors backward to adjust the network.

Size of the error
09Chapter 09 · 2006–2012

Learning From Data By Itself

Can new data be sorted just by memorizing lots of examples?

Thanks to huge amounts of data and GPUs, AI built from many stacked layers of neural networks (deep learning) suddenly became strong. It won by a wide margin at the 2012 image contest. Many of its tools had been growing for a long time. This chapter runs machine learning methods one by one: least squares (1805), Bayes, principal component analysis, k-nearest neighbors, k-means, decision trees, SVM, random forests, singular value decomposition, reinforcement learning, and more. It also takes up Chikio Hayashi's quantification methods, Hirotugu Akaike's AIC and Nobuyuki Otsu's binarization from Japan.

The figure on the right shows one of them, k-nearest neighbors. It remembers points with known answers, and decides the class of a new point by majority vote among its k nearest points. With k set to 1, every training point is classified correctly, but it memorizes even the noise and tends to miss on new points (overfitting). Checking by splitting the data into training and test sets is the heart of thinking in this era.

What you think you knowThe popular story:Hinton invented a new idea in 2006
The original source says:The paper from that year itself wrote that it had been clear since the 1980s that deep networks should be useful.
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What the figure shows:With k set to 1, every memorized point is classified correctly, but noise is memorized too, making errors on new points more likely. That is why data is split into training and test sets.

10Chapter 10 · 2012–2019

Go, Shogi and Predictions About Jobs

Why does playing out randomly to the end show which moves are good?

AI beat top professionals at Go and shogi, and predictions that “jobs will disappear” were talked about around the world. An AI boom also arose in Japan, and the name “third” (boom) spread. This chapter also runs deep-learning tools one by one: autoencoders, GANs, word2vec, object detection, transfer learning, ResNet and more.

One key to strong Go play was Monte Carlo tree search (2006). After trying a move, play randomly to the very end many times, and compare moves by the share of wins. The figure on the right is tic-tac-toe. As you raise the number of trial plays, the winning chances of the good moves become clear. AlphaGo (2016) combined this with neural networks trained on human games and with self-play.

In Japan, in 2015 the Information Processing Society of Japan declared that computer shogi was (translated) with top professional players.

What you think you knowThe popular story:AlphaGo became strong by learning on its own
The original source says:Even the version that beat Lee Sedol in 2016 first learned from human games as models, and then grew stronger through self-play.
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What the figure shows:Even random play, repeated many times, clearly reveals which good moves are more likely to win.

11Chapter 11 · 2017–2022

AI That Makes Text and Images

Which words does a text-writing AI “pay attention” to?

From the mechanism shown in a 2017 paper (the transformer), AI that makes text and images developed, and in 2022 it arrived in a form anyone could use.

One core part of the mechanism is . It decides with numbers how much one word in a sentence looks at each of the other words. In the figure on the right, switch the word you ask about. “Ate” looks hard at who ate (the cat) and at what was eaten (the fish). The numbers are a small example made by this site, not values from a real AI.

An AI that writes text uses this mechanism to work out the probability of the next word and pick words one at a time.

What you think you knowThe popular story:ChatGPT reached 100 million people in 2 months
The original source says:That was not the company's announcement but an estimate by a bank's analysts, worked out from web visits.
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What the figure shows:Numbers determine which other words in a sentence a word pays attention to, and how much. The word “ate” pays attention to who did it (the cat) and what was eaten (the fish).

12Chapter 12 · 2023 and After

Predictions Waiting to Be Checked

If you extend a straight line, do you know the future?

Many of today's predictions rest on the assumption that the link between bigger AI and better performance will keep going. The figure on the right lines up the amount of computation used to train AI (data from Epoch AI) on a scale that grows by 10 times at each step. Draw a line through the points up to some year and extend it, and you have a prediction of the future. Move the year where the line is drawn, and the pace of the prediction changes.

Predictions do not only miss. In 2022, two researchers forecast whether by 2025 an AI would score at gold-medal level in the International Mathematical Olympiad, and in July 2025 it happened. On the other hand, an international report writes that even the people who built today's big AI can barely read what goes on inside it.

Whether a winter will follow the fourth boom is still unknown. This chapter lays out the material without giving an answer.

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What the figure shows:The predicted future pace changes greatly with the last year of data used to draw a straight line. Extending that line into the future assumes that its conditions will continue.

13Chapter 13 · Overview

Waves, Prediction Map, and Unknowns

How many years ahead have AI predictions looked?

Finally, we study this site's own records as data. The figure on the right is a map of predictions. The horizontal axis is the year of the prediction, and the vertical axis is the year in which it said “by this year”. Nearby points are shifted slightly to make them easier to tell apart, and thin lines connect them to their original year positions. If the original year position is above the line for the current year, the prediction's year has not yet come.

A well-known study (2012) found that AI predictions are mostly 15 to 25 years ahead. But on the first page of that paper there is now a note: . The answer changes with how you count and how you collect.

Some predictions in national teaching materials also changed shape when traced to their source. (translated) was originally a figure in a 2005 book about forecasts of computing speed.

What you think you knowThe popular story:Every new technology follows “peak of hope
The original source says:valley of disappointment → settling down” → When researchers checked whether things happen as in the research firm's chart, even the firm's own records did not match. The same pattern each time is a story that looks that way when you line things up, not a fixed law.
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What the figure shows:A study reported that AI predictions often looked 15–25 years ahead, but the study itself later received a note about errors. The answer changes with how predictions are collected and counted.

Closing

The Next Page Is Yours to Write

The history of AI is a record of nearly 400 years of challenges by people who dreamed of thinking machines. There were days when the goal came sooner than expected, and days when it was farther than expected. Each time, someone built a new tool, and the next person used it to take one more step ahead.

On this site, we went back to the speaker's own book or paper to check the famous stories. If you touch the figures and rewrite the Python code, you can run the same mechanisms with your own hands. Read freely, starting from whatever chapter caught your interest.

On the map of predictions, many predictions are waiting to be checked. 2030, 2045 and so on. The people who will see those answers come in are you, the high-school students of today. And the people who write the next prediction or the next invention will surely be some of you, too.