CHAPTER 02/Up to 1955

Dream Machines: Thinking and Calculating

The history before the name existed (to 1955)

Can we tell a machine that looks like a person from a real one? Is thinking just calculation? A question more than 300 years old travels through gears, cards and switches, and arrives at the question of 1950,

011637 · Telling apart

Telling a machine from a person

If a machine moved just like a person, could we tell it apart from one?

In 1637, in Part 5 of the (Discours de la methode), Descartes wrote that even if there were machines built to look like a human body and imitate its actions, there would be (translated) of recognizing that they were not real human beings.

The first is language. Descartes admitted that a machine could be made that, touched in one spot, asks (translated), and touched in another, cries out (translated). But such a machine could not arrange words in many different ways (translated). The second is the breadth of situations it can handle. A machine needs a special arrangement of parts for each action, so it falls short of reason, which he called (translated) that works in any situation.

The figure on the right is a table machine that returns a fixed word to a fixed stimulus. It cannot answer a question that is not in its table. Even if you make the table bigger, the number of sentences you can build from words grows much faster than the table does.

number of arrangements=VL
V
number of words available
L
length of the sentence (in words)

What the figure shows:A machine that gives fixed replies to fixed prompts from a table cannot answer questions outside that table. Enlarging the table cannot keep up, because the number of sentences made by combining words grows much faster.

Sentence length and the share the table covers (the vertical axis goes up in steps of 10 times)
021651 · Thinking = calculating

Is thinking just adding and subtracting?

Can careful reasoning be written down as a calculation?

In 1651, in Chapter 5 of , , Hobbes wrote: . What is added is not numbers but names (words) that people have agreed on. Logicians, he wrote, add names to make statements, and add statements to make syllogisms. Just as people make mistakes in arithmetic, he said, even careful people make mistakes in reasoning.

The figure on the right draws names as circles (sets). The statement "all humans are animals" means emptying the part of the human circle that lies outside the animal circle. Cross out regions using the two premises, and you can read the conclusion from the regions that are left. If you check every case of crossing out and keeping, you can check mechanically whether an argument is valid.

In the introduction, he asks whether an automaton driven by springs and wheels might also be said to have , and goes on to say that human art creates even .

premise 1+premise 2 → conclusion (always true if it holds in every world where the premises are true)
world
which of the 8 regions made by 3 circles contain an element (2⁸=256 combinations)
What you think you knowThe popular story:Hobbes was the ancestor of AI and said thinking machines could be built
The original source says:In the introduction, is a metaphor for the state (the Leviathan). But Chapter 5 does define thinking itself as a calculation with words, so an idea that leads toward later AI is plainly there.

What the figure shows:A statement such as “All humans are animals” removes a region from a circle diagram. Removing regions according to the premises lets a machine check whether a conclusion is valid.

031662–1796 · Japan · Karakuri

The doll that walks with a teacup

How far can a doll go in making fixed movements with only gears and a spring?

In Edo-period Japan, karakuri (mechanical puppets) were a popular show. Around 1662, the first Takeda Omi started a theater devoted to karakuri in Dotonbori, Osaka, called “Takeda’s Theater”, which lasted about 100 years (some books give 1664 as the start).

In 1796, Hosokawa Hanzo Yorinao of Tosa explained, in the (Kikō Zui), with illustrations, the inner workings of 9 kinds of karakuri, including Japanese clocks and tea-serving dolls. The tea-serving doll moves forward when a teacup is set on the tray in its hands, stops when the cup is removed, and turns around and comes back when the cup is set on again. Its power comes from a spring (made of whalebone). The pictures show gears labeled "first wheel" and "second wheel".

In the figure on the right, set the cup on and take it off. The direction, whether it is moving, and whether a cup is present settle the next movement to exactly one choice, and in the same situation it always does the same thing.

next move=table(current state, cup present or absent)
state
a combination of direction (going or returning) and moving or stopped

The figure is a table of the order of movements, not a copy of the gears in the book. Tea-serving dolls themselves existed before the book, and appear in a haiku by Ihara Saikaku.

What the figure shows:A mechanical doll's direction, whether it is moving, and whether it holds a tea bowl determine exactly 1 next action, so the same situation always produces the same movement.

041768–1774 · Automata

A writing doll with swappable steps

How do you build a doll whose sentence can be changed?

From 1768 to 1774, the watchmaker Pierre Jaquet-Droz, his son Henri-Louis, and Jean-Frédéric Leschot built three automata: , “The Musician” and “The Draughtsman”. They write with a quill, draw pictures and play an organ, and they are still in the Neuchâtel Museum of Art and History in Switzerland.

writes short sentences of up to 40 characters. Which sentence it writes is said to be set by the arrangement of knobs that choose the cams (discs with bumps; as a disc turns, a rod moves with the bumps) that move the pen. The result changes with the order in which parts of fixed shape are used. It is the same idea as a later program.

In the figure on the right, press the knobs to rearrange the order, then press "Write". The shapes of the letters stay the same, and only the arrangement changes the sentence.

pen position (x, y)= (radius of cam x, radius of cam y)
cam
a disc that pushes a rod according to its radius as it turns
knob arrangement
which cam is used in which order

What the figure shows:Keeping the parts that form letters unchanged, but changing which parts are used and in what order, changes the sentence written. This is the same idea used in later programs.

051770–1836 · Spectacle

Inside the chess-playing doll's box

Was there really a chess-playing machine in the 18th century?

Around 1770, at the court in Vienna, Kempelen built and showed a machine for Empress Maria Theresa: a doll in Turkish dress that played chess on top of a box. The doll toured Europe and America, but a chess master was actually hidden inside the box. In 1784 a book appeared saying there was a person inside. A book of 1821 explained with a diagram how the person inside slid his body out of sight while the doors were opened one after another to show the interior.

In the figure on the right, open the doors. The person inside moves to the side that is closed. What happens if you open both at once?

In 1836, Poe argued that a pure machine would always win, yet this one sometimes lost, so a person must be moving it. His conclusion was right. But in 1950, Shannon called this reasoning , because a machine that follows fixed rules alone will lose if its rules are poor (you can check this with the Python program).

The machine was destroyed in a fire in Philadelphia in 1854. Some sources give 1769 as the year it was built.

What you think you knowThe popular story:In the 18th century there was a thinking machine that played chess
The original source says:In fact a person was hiding inside. According to the book by his friend Windisch (1784), Kempelen began from the start by hinting to the Empress that he could build a machine that fooled the eye even better, and he called this machine .

What the figure shows:A person hides inside the chess-playing doll's cabinet, moving to the closed side as the doors are opened one after another. Opening both doors at once reveals the person.

061822 · Difference Engine

Number tables without multiplying

Can we hand the toil of repeating the same calculation over to a machine?

In 1822, in an open letter to Davy, president of the Royal Society, the Englishman Charles Babbage described a plan for a machine that would automatically calculate, and even print, tables of numbers used for logarithms and astronomy. At the start of the letter he writes that, out of the great toil of repeating the same calculations, he conceived a machine to stand in for one of the lowest workings of the human intellect. This later came to be called the Difference Engine.

The key is the difference (the difference between neighboring numbers). The squares 1, 4, 9, 16 ... have differences 3, 5, 7 ..., and the difference of the differences is always 2. So if you repeat "add the second difference to the difference, add the difference to the number", you can keep producing the table without using multiplication. Turning the row of gears in the figure on the right once moves the table forward by one row. For a cubic formula, there is one more row of gears.

number(x+1)=number(x)+difference(x)、difference(x+1)=difference(x)+second difference
difference(x)
number(x+1) − number(x)
formula of degree n
the n-th difference is always the same value

The words Difference Engine do not appear in the title of the letter. It is a name that came into use later.

What the figure shows:The differences between the differences of square numbers are always 2. Repeatedly adding differences can therefore keep producing a number table without multiplication.

071843 · Analytical Engine

Bernoulli numbers by repeating steps

Can we write the steps of a calculation and hand them to a machine?

Babbage's next idea was the , which would be given its steps by punched cards and could do any calculation (it was never built). In 1843, Ada Lovelace translated a paper explaining this machine into English and added notes about three times as long as the original. She signed them only A.A.L.

In Note E she called a group of operations that is repeated many times a cycle, and also explained nesting, a repetition inside a repetition. In Note G she showed in detail, with a formula and a table, the steps by which the engine would calculate a sequence of numbers called Bernoulli numbers one after another. With n=1 for B₁, n=2 for B₃, n=3 for B₅, the same formula is repeated while n changes, and each earlier answer is used in the next calculation. It is an algorithm (clearly written steps for solving a problem) with what we now call a loop. In the figure on the right, press "Repeat once".

0= −½·(2n−1)/(2n+1)+B1·(2n/2)+B3·(2n(2n−1)(2n−2)/(2·3·4))+ … +B2n−1
n
number of repetitions
B1, B3 …
Bernoulli numbers (the numbering is as in the Notes)
What you think you knowThe popular story:Lovelace flatly said machines have no creativity
The original source says:In Note G, just before writing that the engine has , she wrote that new things tend to be overrated at first and then underrated in reaction, so we should be careful. She had already described the boom-and-winter pattern in 1843.

What the figure shows:Lovelace's Note G describes repeating the same formula while changing n and using each earlier answer in the next calculation. Today, this would be called an algorithm with a loop.

081854 · Algebra of logic

An algebra of only 0 and 1

Can "and", "or" and "not" be written as calculations with formulas?

In 1854, George Boole published . His aim was to express the laws of the mind's workings when people reason by means of calculation with symbols, like algebra, and to build a theory of logic and probability.

Boole noticed that the symbols of logic obey x×x=x (x² =x). Among numbers, only 0 and 1 satisfy this. So he considered an algebra in which symbols take only the values 0 and 1 (page 37). He wrote the collection of things that are not x as 1 − x, and showed that x(1 − x)=0 expresses the old rule that nothing can be x and not x at the same time (the law of non-contradiction) (pages 48–49).

In the figure on the right, move x. Only 0 and 1 give x² =x. If you make tables for "and", "or" and "not" with 0/1 switches, they match the logic circuit tables studied in Information I (Japan's required high-school informatics course).

x·y (and)、1 − x (not)、x+y − x·y (or)
x, y
values 0 or 1
x+y − x·y
“or” written in today's notation
What you think you knowThe popular story:Boole created 0-and-1 logic for computers
The original source says:The book's aim was to write the laws of the mind's workings in reasoning as symbols. Searching the text by characters, the word machine does not appear in the book. It was engineers about 80 years later who applied it to electric switching circuits (spread 10 of this chapter).

What the figure shows:Only 0 and 1 satisfy x² = x. Calculating with just 0 and 1 produces tables for AND, OR, and NOT that match logic circuit tables.

091920–1942 · Robots

The “robot” and Gakutensoku's drum

When, and as what kind of being, was the robot born?

In 1920, the Czech writer Karel Čapek published the play . The “robot” is an artificial person made from artificial materials, mass-produced to work, and the name is coined from a word for labor. In Karel's own account, when he was struggling to find a name, his brother Josef, a painter, suggested: .

In 1928, Makoto Nishimura, a biologist who was an editorial writer at the Osaka Mainichi newspaper, built an artificial human named “Gakutensoku”, meaning (translated), and showed it at an exposition in Kyoto. It was powered by compressed air. A shaft covered in many wart-like bumps turned, pressing particular rubber tubes for particular lengths of time to stop or let air through. Like the pins of a music-box drum, the order of the bumps is the program of its movements (research report of the Osaka Science Museum).

In the figure on the right, attach and remove the bumps on the drum. You can check the order in which the expression changes.

In 1942 the science fiction writer Asimov wrote the in his short story . In the story, the vagueness of the wording of the rules, and conflicts between the laws, drove the plot.

What you think you knowThe popular story:Gakutensoku was Japan's first robot
The original source says:The Osaka Science Museum's material says it is (translated). The original is said to have gone to Germany and been lost; what exists now is a reconstruction from 2008.

What the figure shows:Gakutensoku's actions are set by the order of bumps on a rotating shaft. Like pins in a music box, their arrangement acts as a program.

101936 · Japan · Circuit algebra

Calculating switch circuits

Can we work out whether a bulb lights without drawing the circuit?

In December 1936, Akira Nakashima and Masao Hanzawa of Nippon Electric (NEC) published in the journal of the Institute of Electrical Communication Engineers of Japan a theory for designing relay circuits (electrically operated switches), used in telephone exchanges and elsewhere, by calculating with symbolic formulas. They described a contact by how hard it is for electricity to pass: 0 if closed, infinity if open. Two contacts in series were written A+B, and in parallel A×B. Then+and × followed rules quite different from ordinary arithmetic. This was the same thing as Boolean algebra, but Nakashima did not know Boolean algebra at the time.

In the figure on the right, press the switches. In the modern notation (connected=1), series means "and" (×) and parallel means "or" (+). In the 1936 notation (connected=0), series becomes+and parallel becomes ×. Either way, the result of whether the bulb lights is the same.

today: series A·B, parallel A+B 1936: series A+B, parallel A × B
A, B, C
switches
+and ×
calculations done with 0 and 1 (1+1 is 1)
What you think you knowThe popular story:Shannon started the theory of designing circuits with Boolean algebra
The original source says:Akira Nakashima and Masao Hanzawa published a theory of calculating relay circuits with formulas in the December 1936 journal of the Institute of Electrical Communication Engineers. The museum of the Information Processing Society of Japan describes it as the same content, two years earlier than Shannon.

What the figure shows:Switch circuits can be calculated by expressing series and parallel connections with + and ×. Whether using the 1936 notation (connected = 0) or today's notation (connected = 1), the answer about whether the lamp lights is the same.

111936 · A model of computing

Calculating with just a tape and a table

What does it mean for something to be computable?

In 1936, Alan Turing published the paper . He reduced the steps a human follows when calculating with paper and pencil to a that runs on a tape divided into squares (in place of paper), a head that reads and writes one square at a time, and only a finite number of states. He defined the numbers this machine can write out as .

The figure on the right is that machine. The head reads one symbol on the tape, looks it up in the rule table, rewrites the symbol, moves one square left or right, and moves to the next state. This alone can add 1 to a binary number. You can also choose the first example from page 233 of the paper, a machine with four states that writes 0 and 1 alternately.

The paper went on to show that if a description of another machine is read from the tape, one machine (the universal machine) can carry out any calculation, and that no fixed procedure exists that always decides whether a logical formula is provable.

(state, symbol read) → (symbol to write, direction to move, next state)
state
one of a finite number of marks inside the machine
table
the list of action rules (the equivalent of today's program)
What you think you knowThe popular story:Turing designed the computer in 1936
The original source says:The paper's is a model in the head that simplifies the steps of a person doing calculations, and the “computer” in the paper meant a person who calculates. The name is not in the paper either; it was given in Church's review the next year.

What the figure shows:A simple machine that reads 1 tape square, rewrites it, and moves can calculate using only a table of rules. Turing called numbers that this machine could write out “computable.”

121943 · Formal neuron

Turning a nerve into a switch

What does a brain's nerve cell look like when written as a formula?

In December 1943, McCulloch and Pitts published the paper . Since the activity of a nerve cell (neuron) is (it fires or it does not), they reasoned that the workings of a network of nerve cells (a neural network) can be written in two-valued logic. It is regarded as the starting point of neural network research.

Their assumptions include that a neuron fires when a certain number of synapses are stimulated at the same time, that a single active inhibitory synapse stops it firing, and that the way the network is connected does not change. In today's words, this is a formal neuron that adds up its inputs and compares the sum with a threshold. Try it in the figure on the right. Threshold 2 gives AND, 1 gives OR, and an inhibiting input gives NOT. XOR (exactly one of the two) cannot be made with one neuron, but can be made by connecting three.

y=1 (when x₁ +x₂ + … ≧ θ and the inhibiting input is 0), otherwise 0
x
input (0 or 1)
θ
threshold
inhibiting input
if even one is 1, the output is always 0
What you think you knowThe popular story:The 1943 model had fixed connections, and learning only came with Hebb in 1949
The original source says:The 1943 paper also dealt with learning. It considered changes in which new synapses form, and wrote that such changes can be replaced by a network with loops (page 124).

What the figure shows:Even a switch that just adds inputs and compares them with a threshold can act as AND or OR by changing that threshold, and as NOT with an input that blocks firing. XOR cannot be made with 1 such switch, but can be made by connecting 3.

131943 · Time and memory

Something cold feels hot for a moment

Can a network of switches remember what came before?

Page 122 of the same paper has a strange example. If you touch something cold to the skin for a moment and take it away, it feels hot, but if you keep it there longer, you feel only cold. The paper wrote the connections between the neurons that receive input at the skin (heat, cold) and the neurons that produce the feeling (hot, cold) as formulas, and explained this illusion. A signal is delayed by one tick each time it passes through a connection. By stacking delays, a network can remember a little of what came just before.

In the figure on the right, change how long the cold touch lasts. For a moment, the "feels hot" side fires after the touch is gone; for a long touch, the "feels cold" side fires.

Page 124 says that if signals form a loop, activity can circle the loop forever. The neuron in the loop in the figure keeps firing once it fires, until a stop signal arrives. It is the simplest memory, one that can hold on to things from long ago.

hot(t)=heat(t−1) or (cold(t−3) and not cold(t−2)) cold-feeling(t)=cold(t−2) and cold(t−1)
t
time (1 tick=the delay of one connection)
heat, cold
firing of the receiving side at the skin
hot, cold-feeling
firing of the feeling side
What you think you knowThe popular story:McCulloch and Pitts showed that neural networks can do any calculation
The original source says:On page 129 of the paper they write that with a tape and a reading device added, the network can compute the same numbers as a Turing machine, and without the tape it can compute only some of them.

What the figure shows:A signal is delayed by 1 time step each time it passes through a connection, so stacking delays stores information from a short time ago. A loop can keep it stored indefinitely.

141946 · Electronic computer

Math robot or electronic brain?

What was the first electronic computer built for, and how was it presented?

In February 1946, the US War Department announced ENIAC, an electronic computer built at the University of Pennsylvania. It had about 18,000 vacuum tubes and weighed 30 tons. It was a machine for calculating firing tables (tables of how shells fly) for guns and bombs. According to the announcement, it could add in 1/5000 of a second and multiply two 10-digit numbers in 1/360 of a second. Its steps were set up by changing the connections of switches and cables.

A firing-table calculation repeats two steps: move the position forward by the speed over a very short time, then change the speed because of gravity and air resistance. In the figure on the right, the finer you make each step, the more accurate it gets, and the more calculation there is. In a 1974 lecture by Burks, who demonstrated it to the press, a shell flight of 30 seconds took a human calculator (the job was also called a computer then) 3 days, and ENIAC 20 seconds. The announcement called it and also wrote that .

x ← x+vxΔt、vx ← vx − k·v·vxΔt (the same for the vertical direction, with gravity g subtracted)
Δt
time of one step
v
speed
k
strength of air resistance (the numbers in the figure are examples chosen by this site)
What you think you knowThe popular story:ENIAC was announced as an electronic brain
The original source says:The War Department's announcement went out of its way to say that it . The words were a phrase made up by newspaper headlines, and in the same year Hartree in Britain also protested against a headline.

What the figure shows:ENIAC calculated tables of artillery shell paths. It repeatedly updated position and speed over short intervals; smaller steps improved accuracy but increased the number of calculations.

151949 · Learning rule

Used connections grow stronger

How does a neural circuit learn from experience?

In 1949, on page 62 of , the psychologist Donald Hebb set out a hypothesis. When cell A repeatedly or persistently takes part in firing cell B, some change takes place in one or both cells, so that A's influence in firing B increases. The idea is that the more a connection is used, the stronger it gets. On the same page he also wrote that there is no direct evidence for such a mechanism.

The figure on the right is the simplest example. B always fires when a food signal arrives. The connection from A (the sound of a bell) to B is weak at first. Each time A and B fire together, the connection gets stronger. Once it passes the threshold, the bell alone makes B fire. The bell and the food are this site's analogy.

This idea is called the , and it became one of the starting points both for research on how the brain works and for learning methods in artificial neural networks.

w ← w+η·xA·yB
w
strength of the connection from A to B
η
how fast the connection strengthens (learning rate)
xA, yB
1 when A or B fires
What you think you knowThe popular story:Hebb said cells that fire together wire together
The original source says:The book's wording is that A . The slogan fire together, wire together was spread in lectures by the neuroscientist Carla Shatz.

What the figure shows:Every time A and B fire together, the connection from A to B grows stronger. Once the threshold is crossed, the bell alone can make B fire.

Connection strength w at each round
161949–1954 · Machine translation

Nearby words fix the meaning

What is missing for a computer to translate language?

In 1949, Warren Weaver of the Rockefeller Foundation circulated to acquaintances a memorandum called , asking whether computers could translate language. If you read a book through a mask with a hole big enough for only one word, you cannot tell whether the word fast means quick or fixed in place. He presented the idea of context: if you widen the hole so that you can see N words on each side, the meaning is fixed.

In the figure on the right, change the width N of the hole. The example sentences and the table of clue words that fix the meaning are examples made for this site. When N is small, the clue falls outside the hole and the meaning comes out wrong.

In January 1954, IBM and Georgetown University held a public experiment translating Russian into English on the IBM 701 computer. It had 250 words and only 6 grammar rules. Dostert predicted that in five, perhaps three years, machine translation .

meaning=table(the nearest clue word within N words on each side)
N
width of the hole (how many words to look at on each side)
What you think you knowThe popular story:Machine translation would be solved in 3 to 5 years
The original source says:The original announcement had a condition. At the same event it also stressed that it was not yet possible to put in a Russian book and get out an English book. The results of the next 10 years fell short of expectations, leading to the 1966 ALPAC report (Chapter 5).

What the figure shows:‘Fast’ may mean ‘rapid’; or it may mean ‘motionless’, so the word alone is not enough to decide its meaning. Seeing the N words before and after it resolves the meaning, but if N is too small, the clue falls outside the window and the meaning is misread.

171864–1950 · Games

Looking ahead to pick a good move

How should a computer choose its moves to play a game?

In 1864, Babbage wrote in his memoir that he had thought .

In March 1950, Claude Shannon of Bell Labs showed a method in the paper . Chess has about 30 moves per turn, and a game of about 40 moves comes to 10 to the 120th power possible games, so you cannot read them all. So you look ahead a few moves and rate the resulting position with a score f(P). Assuming you pick the move with the highest score on your turn and the lowest on your opponent's turn, you carry the scores back to the current position (today called the minimax method).

The figure on the right is a tree of the same shape as Figure 2 of the paper. Change the scores and see which move gets chosen.

best move=maxi minj f(MijMiP)
P
current position
Mi
your move
Mij
opponent's reply
f
evaluation function of a position

What the figure shows:Minimax scores positions several moves ahead, then carries those scores back to the current position, assuming the opponent chooses the smaller score and the player chooses the larger one.

181950 · The imitation game

Replacing a question with a game

How should we answer the question of whether machines can think?

In October 1950, Turing wrote in a paper that the question was , and replaced it with the . The interrogator communicates only in writing with two people in other rooms. It started as a game of guessing which of two people is the man, and he considered how often the interrogator would be wrong if a machine took the man's part.

The paper includes sample questions and answers. Asked to write a poem about the Forth Bridge, the respondent declines, saying it cannot write poetry. Asked to add 34957 and 70764, it pauses for about 30 seconds and answers 105621 (the correct answer is 105721; this site's calculation). He also wrote that a human pretending to be a machine would soon be spotted through slowness and inaccuracy at arithmetic. In the figure on the right, try to guess which of X and Y is the machine.

The year before, the brain surgeon Jefferson said in a lecture that unless a machine could write a poem from feelings it had itself felt, and know that it had written it, we could not agree that machine equals brain. Turing took up this lecture in his paper and answered it. In fact, Jefferson's own words were .

What you think you knowThe popular story:Turing proposed the Turing test
The original source says:The paper calls it the , and the words do not appear in the paper. Nor is it a paper that answers whether machines can think. He replaced that question with a question about a game.

What the figure shows:Turing replaced “Can machines think?” with a game asking whether a machine could be identified through written exchanges alone.

191950–2025 · Checking the forecasts

The 70% yardstick

What happened to Turing's forecast?

In his 1950 paper Turing wrote that in about 50 years an average interrogator, after five minutes of questioning, would have no more than a 70% chance of identifying correctly. In the same paragraph he also wrote that this was a conjecture, and that there is no harm in keeping it separate from established fact. On the radio in 1951 he spoke of a time when, would come from a person or a machine, and in a 1952 discussion, for a format that allows any questions, he answered .

The figure on the right is a yardstick with the year across and the share of correct identification up. According to a 2000 summary paper, no program had yet won the grand prize in the contests with prize money, and machines were usually spotted right away. In March 2025, researchers at a US university announced the share of five-minute conversations judged to be human: 73% for GPT-4.5 and 56% for LLaMa-3.1-405B (an announcement by one research group). Since the format is a choice between two, the shares of correct identification are 27% and 44%.

What you think you knowThe popular story:Fooling 30% of the judges means passing
The original source says:The paper has no pass mark; it was his own conjecture about about 50 years later. A 2000 paper gives examples of it being retold backwards: by the , that is, computers fooling interrogators 70% of the time.

What the figure shows:Turing predicted that, about 50 years later, the chance of correctly identifying the machine would be no more than 70%. In 2025 experiments, the proportions of correct identifications were 27% and 44%.

201903–1956 · Japanese computers

Relays, vacuum tubes and phase

What kind of computers were being built in Japan at that time?

In 1952, the Electrotechnical Laboratory built a prototype of ETL Mark I, Japan's first digital automatic computer, using telephone-exchange relays. In March 1956, Bunji Okazaki of Fuji Photo Film completed, almost single-handedly, FUJIC, an electronic computer with about 1,700 vacuum tubes. It handled lens calculations about 2,000 times faster than calculating by hand.

In 1954, Eiichi Goto, a graduate student at the University of Tokyo, invented the parametron, a uniquely Japanese component. When a circuit of a coil and a capacitor is shaken at almost twice its resonant frequency, an oscillation starts, and its phase settles into one of two states, 0 or π. These stand for 0 and 1, and it was used as a majority-vote logic element. In the figure on the right, choose the three small inputs to start with, and let the oscillation grow. It settles into the phase of the majority.

x″ +ω²(1+h·sin 2ωt)x=0 (the shaking runs at 2ω)
x
oscillation of the circuit
ω
speed of the original oscillation
h
strength of the shaking

What the figure shows:Eiichi Goto's parametron used an oscillating circuit whose phase settled into 2 possibilities, 0 or π, and chose 0 or 1 by a majority vote of 3 inputs.

Closing

What this chapter still can't settle

What does it mean for a machine to produce something new (Lovelace's engine had ), and what does it mean to think? Lovelace in 1843, Jefferson in 1949 and Turing in 1950 argued about it, and it is still not settled. We also still do not know whether a machine being judged human in an experiment in 2025 means that it is thinking.

Some things also cannot yet be confirmed from sources: the manuscript of the 1952 radio discussion, the whereabouts of the original Gakutensoku, the episode where Atom's birthday was first drawn, how far the plans for Babbage's tic-tac-toe machine were actually built, and who first used the name .

What people of the time hoped for was machines that play chess, compose music and translate language (Poe 1836, Lovelace 1843, Shannon 1950). And the mechanisms in this chapter hold the seeds of the two later streams of AI: the stream that thinks with symbols and rules (Hobbes, Boole, Turing, Shannon) and the stream that learns with neural networks (McCulloch and Pitts, Hebb). In the next chapter, between 1955 and 1956, the name is born.