The Mind
From an immortal soul to a network of neurons — the long effort of the mind to understand itself.
Each star is a thinker or work; solid lines draw the constellation of a school, dashed threads the passage of ideas between eras.
Select any point on the timeline to read about it.
All entries by era
The Mind 400 BCE – 2030 CE
From an immortal soul to a network of neurons — the long effort of the mind to understand itself.
- 380 BCE
Plato, Phaedo & Republic. Plato holds that the soul is immortal, distinct from the body, and divided into reason, spirit and appetite. Mind is a higher reality that merely inhabits the flesh — a dualist vision of the self that would echo through Western thought for two millennia.
- 350 BCE
Aristotle, De Anima. Aristotle rejects Plato's separable soul, defining it instead as the 'form' or organising principle of a living body — inseparable from it as sight is from the eye. His naturalistic account makes the study of mind part of the study of life.
- 1637 CE
René Descartes, Discourse on Method. Descartes makes the thinking self the one indubitable certainty and splits reality into mind and matter — a thinking substance and an extended one. His dualism sets the modern agenda: how can an immaterial mind interact with a physical body?
- 1689 CE
John Locke, Essay Concerning Human Understanding. Locke argues the mind begins as a tabula rasa, with all ideas arriving through experience rather than innate at birth. Empiricism turns the study of mind toward how sensation and reflection assemble knowledge, and grounds it in observation.
- 1890 CE
William James, Principles of Psychology. James describes consciousness not as a chain of discrete ideas but as a continuous, flowing 'stream'. Blending philosophy and the new experimental psychology, he makes the felt texture of mental life a serious object of scientific study.
- 1900 CE
Sigmund Freud, The Interpretation of Dreams. Freud argues that much of mental life is unconscious, driven by hidden desires and conflicts that surface in dreams and slips. However contested his methods, he permanently expanded the mind beyond what we are aware of and reshaped how the modern West sees the self.
- 1913 CE
John B. Watson, behaviorism. Watson declares that psychology should abandon introspection and study only observable behavior, stimulus and response. Behaviorism brings scientific rigour but treats the mind as a black box, banishing consciousness from the laboratory for decades.
- 1949 CE
Donald Hebb, The Organization of Behavior. Hebb proposes that learning strengthens the connections between co-active neurons — 'cells that fire together wire together'. He offers a concrete bridge from brain cells to thought and memory, laying a foundation for both neuroscience and neural networks.
- 1950 CE
Alan Turing, 'Computing Machinery and Intelligence'. Turing reframes the question of mind in terms of computation, proposing his imitation game as a test of machine intelligence. He raises the possibility that thought is a kind of information processing — a claim that would drive both cognitive science and artificial intelligence.
- 1956 CE
The cognitive revolution. At a landmark 1956 meeting, work by Chomsky, Miller and Newell reopens the black box, modelling the mind as a system that represents and processes information. Cognitive science overturns behaviorism and makes internal mental states scientifically respectable again.
- 1990 CE
Functional MRI & the 'hard problem'. Functional MRI lets scientists watch the working brain in action, mapping thoughts and feelings to neural activity. Yet as David Chalmers argues in 1995, explaining why any of this is accompanied by subjective experience remains the 'hard problem' of consciousness.
- 2012 CE
Deep learning & artificial minds. The deep-learning breakthrough of the 2010s produces artificial neural networks that recognise images, translate languages and hold conversations. As machines display ever more mind-like behaviour, the ancient question returns transformed: what, if anything, is it like to be one?
The milestones
c. 380 BCE
Plato, Phaedo & Republic
The immortal, tripartite soul
Plato holds that the soul is immortal, distinct from the body, and divided into reason, spirit and appetite. Mind is a higher reality that merely inhabits the flesh — a dualist vision of the self that would echo through Western thought for two millennia.
c. 350 BCE
Aristotle, De Anima
Soul as the form of the body
Aristotle rejects Plato's separable soul, defining it instead as the 'form' or organising principle of a living body — inseparable from it as sight is from the eye. His naturalistic account makes the study of mind part of the study of life.
1637
René Descartes, Discourse on Method
'I think, therefore I am'
Descartes makes the thinking self the one indubitable certainty and splits reality into mind and matter — a thinking substance and an extended one. His dualism sets the modern agenda: how can an immaterial mind interact with a physical body?
1689
John Locke, Essay Concerning Human Understanding
The mind as blank slate
Locke argues the mind begins as a tabula rasa, with all ideas arriving through experience rather than innate at birth. Empiricism turns the study of mind toward how sensation and reflection assemble knowledge, and grounds it in observation.
1890
William James, Principles of Psychology
The stream of consciousness
James describes consciousness not as a chain of discrete ideas but as a continuous, flowing 'stream'. Blending philosophy and the new experimental psychology, he makes the felt texture of mental life a serious object of scientific study.
1900
Sigmund Freud, The Interpretation of Dreams
The unconscious mind
Freud argues that much of mental life is unconscious, driven by hidden desires and conflicts that surface in dreams and slips. However contested his methods, he permanently expanded the mind beyond what we are aware of and reshaped how the modern West sees the self.
1913
John B. Watson, behaviorism
Only behavior counts
Watson declares that psychology should abandon introspection and study only observable behavior, stimulus and response. Behaviorism brings scientific rigour but treats the mind as a black box, banishing consciousness from the laboratory for decades.
1949
Donald Hebb, The Organization of Behavior
Mind rooted in neurons
Hebb proposes that learning strengthens the connections between co-active neurons — 'cells that fire together wire together'. He offers a concrete bridge from brain cells to thought and memory, laying a foundation for both neuroscience and neural networks.
1950
Alan Turing, 'Computing Machinery and Intelligence'
Can machines think?
Turing reframes the question of mind in terms of computation, proposing his imitation game as a test of machine intelligence. He raises the possibility that thought is a kind of information processing — a claim that would drive both cognitive science and artificial intelligence.
1956
The cognitive revolution
The mind as an information processor
At a landmark 1956 meeting, work by Chomsky, Miller and Newell reopens the black box, modelling the mind as a system that represents and processes information. Cognitive science overturns behaviorism and makes internal mental states scientifically respectable again.
1990
Functional MRI & the 'hard problem'
Watching the living brain
Functional MRI lets scientists watch the working brain in action, mapping thoughts and feelings to neural activity. Yet as David Chalmers argues in 1995, explaining why any of this is accompanied by subjective experience remains the 'hard problem' of consciousness.
2012 →
Deep learning & artificial minds
Machines that seem to think
The deep-learning breakthrough of the 2010s produces artificial neural networks that recognise images, translate languages and hold conversations. As machines display ever more mind-like behaviour, the ancient question returns transformed: what, if anything, is it like to be one?