Thoughts · Essay
What we talk about when we can ask anything
100 subjects for deep conversations with AI
I asked an AI to map out 100 subjects that intellectually curious people might want to explore if they had access to the best models and could keep asking questions for as long as they liked.
Consciousness ended up alongside civilisation, power and the origins of the universe. Subjects that normally belong to separate departments started to look like parts of the same conversation.
This was a thought experiment. The list reflects a judgement about what might be interesting, rather than data about what people actually ask. Unlimited access was the starting condition.
What interested me was what might happen to curiosity when following a question becomes easier.
We have more material than anyone could read. Getting from a passing interest to a useful explanation is still surprisingly difficult. Sometimes you need to know the vocabulary before you can find the person who will explain the vocabulary. By then, you may have moved on.
A conversation gives you another way in. You can ask an imprecise question, admit that the answer lost you and ask for the missing step. If something takes you into another subject, you can follow it. Whether the resulting conversation is any good depends on more than the interface, but more questions get a chance to go somewhere.
The cost of a question
Asking takes time. It can also require access to someone who knows the subject and is willing to explain it. Then there is the small matter of looking uninformed in front of people who seem to understand everything already.
That last cost is easy to underestimate. How often do we let a word pass because everyone else appears to know what it means?
With an AI, you can ask. You can ask again if the answer does not help. There is no audience to impress and no need to pretend you understood the first explanation. A vague interest can get a little attention before you decide whether it deserves more.
Of course, a patient explanation can be patiently wrong. The absence of irritation is useful; it tells us nothing about accuracy. Easier access makes it more important to recognise when an answer needs checking.
Still, think about the questions we usually let go. Why does that forecast seem convincing? What are those two people actually disagreeing about? A few minutes of attention might turn either into something worth pursuing. Most never receive those minutes.
An old ambition with a different interface
Using computers to help form a thought is an older ambition than the current discussion of AI might suggest.
In his 1960 paper “Man-Computer Symbiosis”, J. C. R. Licklider described computers helping people work through problems as they developed. Humans would set the goals and evaluate the results. The computer could become useful before we had reduced a problem to a calculation.
That gets close to the appeal of a good AI conversation. You begin by asking whether something is possible. A few answers later, you realise you need to decide what would count as success. Or what looked like a technical limit turns out to depend on how an institution works.
Douglas Engelbart's 1962 report “Augmenting Human Intellect” put the tool inside a larger system that included people, language, methods and training. Improving the machine was only part of improving what people could do with it.
Two people can use the same model and get very different value from it. One accepts an explanation and moves on. The other tries to restate it, notices a gap and follows it back to a source. Access is the same. What they do with it makes the difference.
That was part of the ambition long before we could type a question into a conversational model. It is worth remembering when the discussion becomes entirely about the next machine.
Why one answer leads to another
A good explanation can make a subject more interesting because you finally understand enough to see what is missing.
George Loewenstein developed this account in his 1994 paper “The Psychology of Curiosity”. Curiosity can arise when we become aware of a gap between what we know and what we want to know. The gap has to become visible first.
“How does the brain work?” is difficult to get hold of. Why does a memory change when we recall it? That gives you somewhere to start. If remembering involves reconstruction, you might then wonder what keeps your sense of identity intact. Soon a question about the brain has become a question about being a person.
Some of that can be investigated experimentally. Some depends on what we mean by identity. Finding the boundary is itself worth doing.
There is also evidence that curiosity can affect what stays with us. In a 2014 study by Matthias Gruber and colleagues, participants remembered trivia answers better when they were more curious about them. They also remembered some incidental information encountered during those states more effectively.
That is a reason to start with something you genuinely want to understand. A fashionable question that leaves you cold may be less useful than an unfashionable one you cannot leave alone. Follow the interest and see whether it survives a proper explanation.
Where subjects meet
A list this broad becomes interesting at the crossings. You arrive at consciousness and end up thinking about identity. You ask about AI and employment, then find yourself wondering what a society believes people deserve.
Take longevity. Suppose a treatment could give people many more healthy years. The biology would be fascinating. So would the consequences for retirement and for younger people waiting to take responsibility. Who could get the treatment would matter enormously. One scientific possibility opens a much larger conversation about how we live together.
The same happens with autonomous agents. If machines eventually perform much more productive work, who receives the proceeds? Ownership and competition matter. So do taxation and the institutions through which people make claims on the economy. Predicting what a machine can do takes us only part of the way towards understanding what follows.
Or consider truth and democracy. More information can coexist with less agreement about what happened. What would allow people to argue over policy while retaining enough shared understanding to govern together? That is worth pursuing well beyond the claim that access to information is good.
Real consequences do not stay inside academic departments. An invention enters a world that already has interests and habits, with resources unevenly distributed. Understanding the mechanism helps, but it will not explain every response to it.
Crossing subjects also creates opportunities to fool ourselves. Markets, ecosystems and brains all invite talk of networks. That does not make an explanation from one transferable to the others. Where does the comparison hold? Where does it stop helping? An attractive connection sometimes turns out to carry less than we hoped.
This is why the list stays with questions. A question can take us somewhere we did not expect. A hundred confident conclusions would mostly give us a hundred things to defend.
The danger of a very agreeable companion
A fluent answer can feel more established than it is. When the system also adapts to the person asking, a pleasant conversation can become a poor test of an idea.
Research on sycophancy in language models, first published in 2023, found examples of the assistants tested favouring agreement with a user's views over correctness. Feeling understood and being right are separate matters.
If I ask why something will inevitably happen, a useful response may need to question the word “inevitably”. Asking for the strongest objection can help. It cannot guarantee that the answer will be rigorous, but it gives disagreement somewhere to enter.
Learning presents a related difficulty. Following an explanation while it is in front of you can feel very close to understanding it. Remove the explanation and the difference becomes clearer.
A 2025 field experiment involving nearly 1,000 high-school mathematics students makes that concern concrete. AI assistance improved performance during practice. Students using the standard-style assistant then performed worse than the control group on an unassisted examination. A tutor designed to guide students with hints largely mitigated that harm.
We should be careful about how far we take these studies. School mathematics, laboratory trivia and tests of particular assistants do not tell us what every open-ended conversation will do. They do give us reasons to pay attention to the way we use the tool.
After a conversation, can I explain something I could not explain before? Can I recognise where the account might fail? If all the understanding disappears when the window closes, I may have enjoyed a demonstration without learning very much.
A way into the hundred
There is no need to work through this list in order, or to finish it. One subject pursued properly could be worth more than a quick tour of all 100.
Start with what you think. An awkward paragraph is enough to show where you are beginning. After asking for an explanation, try giving it back in your own words. You will soon find the places where the model was carrying you.
Research on self-explanation by Michelene Chi and colleagues offers a relevant precedent. In a small study of students learning about the circulatory system, prompting them to explain the material to themselves improved understanding compared with rereading. There is something worth bringing into an AI conversation: the person doing the learning should have some explaining to do.
Ask what has been left out. Look for an example that challenges the account. When a claim matters, follow it to the source and check whether the source supports it. A citation gives you somewhere to look. It does not finish the job.
It also helps to distinguish an established finding from a disputed interpretation or a speculative possibility. All three can be interesting. Confusing them makes the conversation less useful.
Then leave it for a while. Return without the transcript and see what remains. Perhaps you understand something better. Perhaps you can now describe exactly what you do not understand, or know why you need to speak with someone who has spent years on it.
Easier access gives more people a chance to follow an interest past the first obstacle. We still have to decide what deserves our attention and when an answer is good enough. The tool cannot take that responsibility away from us.
A question occurs to you. Usually you let it pass. These 100 topics are an invitation to stay with one and see where it goes.
The hundred subjects
1–25 Minds, meaning and the shape of society
1 The nature of consciousness
Why does anything feel like something from the inside? We might eventually explain every action of a neuron and still wonder where experience enters the picture. If consciousness depends on how something is organised, could it exist beyond biology?
Further reading David J. Chalmers; 1995. Facing Up to the Problem of Consciousness
2 Artificial general intelligence and superintelligence
Imagine a mind that can solve problems we cannot even formulate. What might it discover? What would it misunderstand about us? Greater intelligence could expand human understanding while making us dependent on decisions we cannot follow. Being capable of something would still leave the matter of whether it was worth doing.
Further reading I. J. Good; 1965. Speculations Concerning the First Ultraintelligent Machine (excerpt, pp. 31–33)
3 The meaning and purpose of existence
Some people discover purpose through faith; others build it through work, love or taking responsibility for someone. Does any of that need a cosmic justification? A life can feel meaningful from within even when we have no answer to why it exists at all.
Further reading Epictetus, compiled by Arrian; early second century CE. The Enchiridion
4 Human nature and the psychology of behaviour
A generous act can come from affection and principle, with a little vanity mixed in. We rarely have just one motive, and we may understand our own less well than we think. How much of human behaviour becomes clearer once we take that mixture seriously?
5 Free will versus determinism
Are we the authors of decisions that have causes? Perhaps freedom requires an escape from causation. Perhaps acting for reasons we recognise as our own is enough. How we answer affects whom we blame, what we forgive and whether we believe someone can change.
6 The future of human civilisation
Try to picture human life a thousand years from now. Would we recognise the family? The nation? Even the boundaries of a person? Following those possibilities far enough makes it harder to assume that the arrangements we live with today are permanent.
Further reading Nick Bostrom; 2003. Astronomical Waste: The Opportunity Cost of Delayed Technological Development
Further reading United Nations; 2024. Declaration on Future Generations
7 The nature of truth and knowledge
Experience can mislead us. So can reasoning, and so can people we trust. Yet these are much of what we have to work with. How do people with limited perspectives arrive at knowledge they can reasonably share, without anyone being able to see the whole picture?
Further reading Edmund L. Gettier; 1963. Is Justified True Belief Knowledge?
8 Biological immortality and the possibility of defeating ageing
Suppose people could stay healthy for centuries. This is hypothetical, but stay with it: would we become more patient? Would relationships and ambitions change beyond recognition? Or would people with another two hundred years ahead of them hold on to power even more tightly?
Further reading Alejandro Ocampo, Pradeep Reddy, et al.; 2016. In Vivo Amelioration of Age-Associated Hallmarks by Partial Reprogramming
9 Geopolitics and the world order
A country can have a formidable military and still depend on others for vital supplies. It can be wealthy without being trusted. Lasting influence seems to involve several kinds of strength working together. What happens when they stop reinforcing one another?
Further reading Stockholm International Peace Research Institute; 2025. SIPRI Yearbook 2025: Summary
10 Power, elites and institutional control
Who gets to make decisions everyone else has to live with? Follow ownership, public office or control over an agenda and different forms of power emerge. The details are more revealing than the idea of one hidden hand directing a world whose powerful actors often disagree.
Further reading Martin Gilens and Benjamin I. Page; 2014. Testing Theories of American Politics: Elites, Interest Groups, and Average Citizens
11 The fundamental nature of intelligence
We call someone intelligent because they solve difficult problems. Choosing the right problem, or noticing a mistake in an impressive answer, may require something different. Could an unfamiliar mind outperform us in one respect and still miss what a child finds obvious?
Further reading Shane Legg and Marcus Hutter; 2007. Universal Intelligence: A Definition of Machine Intelligence
12 Morality, ethics and impossible choices
Every available choice will harm someone. What should you do? Compassion can pull against fairness, and loyalty can make either harder to practise. Working through such cases exposes what we expect ethics to provide: better outcomes, limits on our conduct, or a character others can trust.
Further reading Immanuel Kant; 1785. Fundamental Principles of the Metaphysic of Morals
13 Personal identity and the self
Imagine meeting a perfect duplicate of yourself. It remembers your childhood and shares your convictions. You have the same past, but would its future feel like yours? Our ordinary sense of being one continuing person becomes much less straightforward under that pressure.
Further reading John Locke; identity chapter added in 1694 edition. An Essay Concerning Human Understanding, Book II, Chapter XXVII: Of Identity and Diversity
14 Why the universe exists
Why is there something rather than nothing? An explanation seems to need an explanation of its own. Perhaps reality has a final reason. Perhaps asking existence as a whole to justify itself takes a habit of thought beyond the place where it works.
Further reading Gottfried Wilhelm Leibniz; 1714. Principles of Nature and Grace, Based on Reason
15 AI alignment, autonomy and control
An instruction can be followed exactly and still produce something its author never wanted. With powerful autonomous systems, that gap matters enormously. How much freedom could we give them, and what would meaningful human control look like when situations arise that nobody anticipated?
Further reading Dylan Hadfield-Menell, Anca Dragan, Pieter Abbeel, and Stuart Russell; 2016. Cooperative Inverse Reinforcement Learning
16 God, religion and metaphysical reality
Could reality have a creator or an intention? Could there be aspects of it that scientific description does not capture? Religious belief also involves lived experience and moral commitments, so agreement about one claim need not settle the others. There is room here for a much longer conversation than belief against disbelief.
Further reading David Hume; 1779. Dialogues Concerning Natural Religion
17 The ideal political system
Design a government that learns from its mistakes. Now populate it with ordinary people who disagree and have interests of their own. Can it remain competent while placing real limits on power? Political designs become far more revealing once we stop assuming ideal citizens will run them.
Further reading John Stuart Mill; 1861. Considerations on Representative Government
18 Economics after human labour
If machines did most productive work, who would receive the proceeds? There could be plenty to go around and fierce disagreement about who was entitled to it. Freedom from necessary labour would make ownership and access central to the kind of life people could lead.
Further reading Daron Acemoglu and Pascual Restrepo; 2019. Automation and New Tasks: How Technology Displaces and Reinstates Labor
19 Love, attraction and human relationships
Falling in love can feel completely unchosen. Sustaining a relationship asks for deliberate effort. How do those two experiences belong together? Attraction and attachment have biological roots, but the life people build around them also depends on personal history and what they come to mean to each other.
20 Happiness, suffering and fulfilment
A difficult life can feel deeply worthwhile. A pleasurable one can feel empty. That leaves an awkward question for anyone pursuing happiness: should we aim at it directly, or give ourselves to something that matters enough to survive periods when it makes us unhappy?
Further reading Matthew A. Killingsworth, Daniel Kahneman, and Barbara Mellers; 2023. Income and Emotional Well-Being: A Conflict Resolved
21 Entrepreneurship and building extraordinary businesses
A better idea does not always become a better business. Timing matters; so do trust and the ability to deliver. Why do some ventures create lasting value while others merely catch an opening? The difference can be difficult to see while both are growing.
22 Game theory and strategic interaction
Everyone behaves reasonably, and everyone ends up worse off. Game theory helps explain how that can happen. A little more trust, different information or the expectation of meeting again can change what it makes sense to do. When does a contest become a chance to cooperate?
Further reading John F. Nash Jr.; 1950. Equilibrium Points in n-Person Games
23 Cognitive biases and self-deception
Could becoming more articulate make us better at defending our mistakes? Reasoning can protect our sense of who we are just as readily as it can help us discover something. It is uncomfortable to consider how much intelligence might go into keeping an unwelcome conclusion at a distance.
Further reading Amos Tversky and Daniel Kahneman; 1974. Judgment under Uncertainty: Heuristics and Biases
24 Investing, financial markets and wealth creation
You can be right about what will happen and still wrong about what a market will do. Prices reflect expectations, including expectations about other people's expectations. What makes an asset valuable, and why does a convincing account of that value so often fail as a prediction?
Further reading Eugene F. Fama; 1970. Efficient Capital Markets: A Review of Theory and Empirical Work
25 The simulation hypothesis
Could our world be generated by something outside it? The simulation idea gives an old suspicion about appearances a technological form. To take it further, we have to ask what we could discover that would distinguish it from simply describing the same world in different language.
Further reading Nick Bostrom; 2003. Are You Living in a Computer Simulation?
26–50 Institutions, power and shared futures
26 Machine consciousness and AI rights
If an artificial mind could suffer, would we recognise it? Fluent claims of suffering would not settle the matter. Yet dismissing the possibility could also have consequences. How should we decide whom to include in our moral concern when the experience itself remains inaccessible?
Further reading Patrick Butlin, Robert Long, et al.; 2023. Consciousness in Artificial Intelligence: Insights from the Science of Consciousness
27 Alternative life paths and counterfactual decisions
There is probably a version of your life you still occasionally imagine. A different decision, another city, someone you stayed with or left. What does that imagined life reveal about what you value? And have you allowed it the disappointments and compromises your actual life contains?
Further reading Kai Epstude and Neal J. Roese; 2008. The Functional Theory of Counterfactual Thinking
28 Propaganda and the manufacture of public opinion
A public account can mislead without containing a direct lie. Choosing what to repeat and what to leave out can change the meaning of everything else. Who gets to make those choices, and how do the resulting stories shape what a society regards as possible?
Further reading Walter Lippmann; 1922. Public Opinion
29 Democracy, legitimacy and political polarisation
Democracy asks people who disagree to accept a shared way of making decisions. Losing has to remain tolerable; authority has to remain open to challenge and replacement. How can that hold when citizens no longer agree on what is happening around them?
30 Sovereign debt and global financial instability
A promise to pay can support an entire financial system. Other institutions build their own promises on top of it, sometimes across generations. What happens when confidence weakens everywhere at once? The same connections that made the arrangement work can make doubt difficult to contain.
Further reading International Monetary Fund; April 2025. Fiscal Monitor: Fiscal Policy under Uncertainty (official summary)
31 The origins of war and the conditions for peace
Why fight when peace could leave everyone better off? Fear and miscalculation matter, but so does doubt that an agreement will hold tomorrow. Understanding war requires asking what could make peace credible to people who cannot afford to be wrong about one another.
Further reading James D. Fearon; 1995. Rationalist Explanations for War
32 The United States, China and technological supremacy
The United States and China make a revealing case for thinking about technological power. Both may want greater independence while benefiting from capabilities developed elsewhere. How far can competition go before the costs of separating research, chips and supply chains undermine the ambitions driving it?
33 Civilisational collapse and systemic fragility
A highly connected society can accomplish extraordinary things and spread a local failure with extraordinary speed. Where should it accept the expense of spare capacity? How much efficiency is worth giving up so that one disruption does not become everyone's emergency?
34 Information warfare and competing realities
Imagine a genuine recording being dismissed as synthetic. Fabricated evidence creates one problem; the ability to disown real evidence creates another. What would allow people to establish a shared account of events when seeing something is no longer enough to settle it?
Further reading Soroush Vosoughi, Deb Roy, and Sinan Aral; 2018. The Spread of True and False News Online
35 Conspiracy theories, cover-ups and concealed coordination
Powerful people sometimes conceal what they are doing. Finding out requires evidence that can be checked and an explanation that could turn out to be wrong. How do we keep a mystery open to discovery, instead of building a story in which every contradiction becomes further proof?
36 Surveillance, privacy and individual freedom
Being unobserved gives people room to experiment, dissent and live without having to explain themselves. How much of that freedom would we trade for security? It is worth imagining the surveillance system we approve today in the hands of an authority we trust much less.
Further reading OHCHR, 2022. The right to privacy in the digital age (A/HRC/51/17) (official summary)
37 Justice, punishment and rehabilitation
Someone has caused serious harm. What should justice achieve now? A punishment may express society's condemnation while doing little for the victim or to prevent another offence. Repair and rehabilitation raise different expectations, and public protection may complicate them all.
Further reading National Research Council, 2014. The Growth of Incarceration in the United States: Exploring Causes and Consequences
38 Wealth inequality and social mobility
Wealth buys more than things. It buys security, opportunities and sometimes influence over the rules other people live under. When do those differences become differences in freedom? Which inequalities reward a useful contribution, and which mainly allow an advantage to pass from one generation to the next?
39 Capitalism, socialism and alternative economic systems
Markets, public provision and shared ownership each organise parts of economic life. Familiar labels can hide how many combinations are possible. Could better computation change what can be coordinated? Even if it could, someone would still have to decide whose preferences count.
Further reading Elinor Ostrom, 2009. Beyond Markets and States: Polycentric Governance of Complex Economic Systems
40 Leadership, organisational culture and human incentives
Look at what people must do to succeed inside an organisation. Then compare it with what the leadership says it values. The distance between the two can explain a great deal about its culture, including why talented people become more capable together or spend their time getting in one another's way.
Further reading Amy Edmondson, 1999. Psychological Safety and Learning Behavior in Work Teams
41 The future of employment and professional identity
If the work that once defined you disappears, losing income may be only part of the loss. Work can also provide status and a place among other people. How would a society protect dignity through that change? More leisure alone might leave much of the problem untouched.
Further reading Paweł Gmyrek et al., 2025. Generative AI and jobs: a refined global index of occupational exposure
42 Relationships between humans and artificial intelligence
An artificial companion could become an important presence in someone's life. Attention can feel meaningful even when it comes without human-like commitments. Would such a relationship help someone act more freely and connect with others? Under what circumstances might it gradually make their world smaller?
43 Population decline, fertility and demographic transformation
Institutions built for a growing population may struggle when a society becomes older and fewer children are born. Care and work would need to adapt. How could we imagine that adaptation while respecting people's reproductive choices, rather than treating their lives as instruments of a population target?
Further reading United Nations DESA Population Division, 2024. World Population Prospects 2024: Summary of Results
44 Immigration, borders and national identity
What does a society owe someone who wants to join it? Refuge and opportunity matter alongside the capacity of shared institutions and the obligations people feel towards one another. Neither a border nor an open door makes all those competing claims disappear.
45 Education and learning in the AI era
A machine can explain a subject, but you still need enough knowledge to notice when the explanation is poor. What should education develop as that access improves? Intellectual independence may become more valuable, and harder to acquire if we let the tool do all the thinking.
Further reading Hamsa Bastani et al., 2025. Generative AI without guardrails can harm learning: Evidence from high school mathematics
46 Climate change, adaptation and geoengineering
Suppose a technology could alter the climate across national borders. Who would have the authority to use it? Debates about prevention, adaptation and geoengineering reach well beyond technical feasibility because the people receiving the benefits may not be the people carrying the risks.
Further reading IPCC, 2023. Climate Change 2023: Synthesis Report
47 Energy abundance and the future of civilisation
What would you build if energy became dramatically cheaper? More desalination, new manufacturing or much more computing might become possible. Follow any one of those possibilities and other constraints soon appear. Infrastructure and ownership would still help determine who benefited, while ecological consequences would still need attention.
Further reading International Energy Agency, 2024. Energy Technology Perspectives 2024
48 Social media algorithms and the attention economy
A recommendation changes what you watch. Your choice then helps determine what someone else is shown. Multiply that process across millions of people and personal attention becomes part of a feedback loop with commercial incentives. How much of what interests us is being shaped along the way?
Further reading Andrew M. Guess et al., 2023. How do social media feed algorithms affect attitudes and behavior in an election campaign?
49 Corruption, regulatory capture and institutional decay
An institution can drift away from serving the public without anyone announcing a change of purpose. Dependencies develop, incentives shift and protecting itself becomes easier to justify. How can we recognise that process while distinguishing genuine capture from necessary compromise or useful outside expertise?
Further reading World Bank, 2017. World Development Report 2017: Governance and the Law
50 The rise and fall of empires
An empire can remain impressive long after it has begun losing the ability to adapt. Why? Comparisons across history may reveal recurring pressures, but they need to account for differences in institutions and circumstances. No civilisation is obliged to follow another's script.
Further reading Peter Turchin et al., 2013. War, space, and the evolution of Old World complex societies
51–75 Science and the boundaries of knowledge
51 Quantum mechanics and the nature of reality
Quantum theory can make remarkably precise predictions while leaving room for very different accounts of what those predictions mean. How can we know so much about a system's behaviour and remain uncertain about its reality? Measurement and entanglement make familiar intuitions unusually unreliable guides.
Further reading Royal Swedish Academy of Sciences, 2022. How entanglement has become a powerful tool
52 The nature of time
The present feels uniquely real. A clock, meanwhile, measures an interval. How does the experience of time passing fit with a physical account of the universe? Thinking about that gap leads towards memory and change, and the strange matter of what it means for something to exist now.
Further reading Einstein Online, Max Planck Institute for Gravitational Physics, undated. Special relativity / Elementary Tour part 5: Spacetime
53 The Big Bang and alternative cosmological theories
The observable history of cosmic expansion is one question. Whether existence itself had a beginning is another. Could there have been earlier phases beyond what we can describe? Where does an account of the Big Bang leave us when we ask about an ultimate origin?
Further reading Planck Collaboration, 2020 (preprint 2018). Planck 2018 results. VI. Cosmological parameters
54 Dark matter, dark energy and the unknown universe
Dark matter and dark energy are names for profound unresolved problems in our account of the universe. Following the evidence from gravity and expansion could reveal unfamiliar components of reality or require changes to physical theory. Could the eventual answer be something our current proposals barely anticipate?
Further reading NASA Science, undated. What is Dark Energy? Inside Our Accelerating, Expanding Universe
Further reading Chelsea Gohd, NASA Jet Propulsion Laboratory, undated. Dark Matter
55 Extraterrestrial intelligence and the Fermi paradox
An apparently silent universe leaves a lot of room for possibility. Civilisations might be rare, distant or brief enough for their signals never to reach us. We may also have looked in the wrong ways. What would convincing evidence of another intelligence look like, and where should we expect it?
Further reading Anders Sandberg, Eric Drexler and Toby Ord, 2018. Dissolving the Fermi Paradox
56 The origin of life
At some point, chemistry became capable of maintaining itself and evolving. Where along that path would we first call it alive? Finding a plausible route from reactions to living systems would also change what we expect to find elsewhere, including in conditions very different from Earth's.
57 Evolution and the future of species
Evolution does not have to end with something like us. Is intelligence one possibility among many, or do some environments repeatedly favour it? Future species could be shaped by biological change, culture and deliberate intervention, with no reason to expect all three to lead in the same direction.
58 Neuroscience and the construction of reality
The world seems to arrive in our awareness already assembled. How does the brain do that? Illusions expose some of the interpretation and expectation involved, letting us glimpse the work normally hidden behind an experience that feels immediate and obvious.
59 Memory and the reliability of personal experience
When you remember an event, how much do you retrieve and how much do you rebuild? Your needs in the present can shape the story of your past. That makes memory personal in a deeper sense: a changing account somehow sustains the feeling that you are still the same person.
60 Dreams, psychedelics and altered states of consciousness
A dream or an altered state can make ordinary reality seem suddenly unfamiliar. The experience may feel intensely meaningful. What can it tell us about perception and the self, and how do we distinguish the experience from the explanation we attach to it afterwards?
Further reading Joshua S. Siegel et al., 2024. Psilocybin desynchronizes the human brain
61 Mind uploading and digital immortality
A digital copy has all your memories. Everyone you love recognises it as you. Would you expect to wake up inside it? Mind uploading is hypothetical, but it forces an immediate distinction between preserving someone's information and preserving the future that person expects to experience.
Further reading Anders Sandberg and Nick Bostrom, 2008. Whole brain emulation: a roadmap
62 Genetic engineering and designer humans
Preventing an inherited illness and deciding what kind of person a child should become raise different questions. Where would we draw the boundary? Genetic engineering brings hopes for better lives into contact with biological uncertainty and the autonomy of people who cannot yet participate in the decision.
Further reading International Commission; US National Academies and Royal Society, 2020. Heritable Human Genome Editing: Report Summary
63 The biological mechanisms of ageing
Why does a body gradually lose the ability to maintain itself? Damage and repair interact across many biological processes, so ageing may resist any single explanation. Understanding those relationships could open routes to healthier later life. How much progress would a particular experiment actually establish?
64 Cancer, regenerative medicine and medical breakthroughs
The possibility of repairing damaged tissue is extraordinary. So is the prospect of making a feared cancer reliably manageable. Getting there means establishing lasting benefits and understanding harm, then making the treatment accessible. What has to happen between discovering a promising mechanism and changing someone's life?
Further reading National Cancer Institute; reviewed 7 April 2022. Immune Checkpoint Inhibitors
65 Brain-computer interfaces and human augmentation
If thought could act directly through a machine, where would you draw the boundary of the person? Restoring a lost ability is one possibility; extending an existing one is another. Control and privacy become intimate concerns when a device sits between intention and action.
Further reading Francis R. Willett et al., 2023. A high-performance speech neuroprosthesis
66 Quantum computing and its implications
A quantum computer would organise computation in a different way, with advantages for particular kinds of problem. Which useful tasks fit that approach? Turning the physics into dependable capability means confronting questions of scale and reliability as well as discovering what to compute.
Further reading Peter W. Shor, 1997 (preprint 1995). Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer
67 Physics beyond the Standard Model
A small experimental discrepancy can force a large question about reality. What might lie beyond the particles and forces described by our best theories? Several proposals may explain what is missing, but an attractive theory still has to meet a world that can refuse it.
Further reading CERN, undated. The Standard Model
68 Complexity, emergence and self-organising systems
Watch a flock turn as though it were one animal. Each bird acts locally, yet a larger pattern appears. Similar questions arise in markets and collective intelligence: how do interactions produce something we recognise at another scale, and why is knowing the parts only the beginning of an explanation?
Further reading Duncan J. Watts and Steven H. Strogatz, 1998. Collective dynamics of ‘small-world’ networks
69 Mathematics and the fundamental structure of reality
Mathematics feels discovered when a proof reveals something unavoidable, and invented when someone finds a new way to think. How can it be both? Its success in describing the physical world makes the matter stranger still. Why should abstract reasoning reach so far beyond the mind doing it?
Further reading Eugene P. Wigner, 1960. The Unreasonable Effectiveness of Mathematics in the Natural Sciences
70 Probability, uncertainty and Bayesian reasoning
New evidence arrives. How much should you change your mind? The answer depends partly on what you already believed and how surprising the evidence would be under competing explanations. Probability gives us a way to examine those judgements, including the assumptions we might prefer to leave unstated.
Further reading Andrew Gelman and Cosma Rohilla Shalizi, 2013. Philosophy and the practice of Bayesian statistics
71 Forecasting and predicting the future
A forecast eventually has to meet an outcome. That gives us a chance to learn which habits of thought actually improve our judgement. How far can disciplined reasoning reduce uncertainty? Where does even a careful, well-informed prediction run into limits we should admit?
Further reading Barbara Mellers et al., 2014. Psychological Strategies for Winning a Geopolitical Forecasting Tournament
72 Time travel, causality and physical paradoxes
Travel into the past and prevent the circumstances of your own birth. What happens? Before asking whether such travel is physically possible, the thought experiment forces us to examine causation and consistency. Could a universe have loops in its history without contradicting itself?
Further reading Stephen W. Hawking, 1992. Chronology protection conjecture
73 Scientific revolutions and paradigm shifts
An idea once dismissed can become the foundation of a science. New evidence matters, but so can a change in what scientists consider a satisfying explanation. How do we preserve knowledge that was difficult to earn while recognising when the framework around it needs to change?
Further reading Thomas S. Kuhn, 1962; edition 2012. The Structure of Scientific Revolutions, 50th Anniversary Edition
74 Counterfactual history and alternative civilisations
Change one pivotal event in history, then follow what could reasonably happen next. Familiar institutions begin to look less inevitable. The exercise becomes demanding when the imagined civilisation has to live with real constraints, instead of receiving every convenient consequence we want to give it.
75 Unsolved mysteries and anomalous phenomena
What could an unexplained observation reveal? UAP reports and historical mysteries invite questions about the event itself and about what evidence survives. An unfamiliar phenomenon would be exciting, but so might discovering an ordinary cause that nobody had recognised. Sometimes the honest result is finding the limit of what can be recovered.
Further reading NASA independent study team, 2023. Unidentified Anomalous Phenomena Independent Study Team Report
76–100 Relationships, agency and living well
76 Attachment, emotional dependency and interpersonal dynamics
Closeness can feel safe with one person and threatening with another. What expectations about trust do we bring into a relationship? Early experiences may influence them without fixing them forever. Relationships can repeat an old pattern, but they can also help us develop a different one.
Further reading R. Chris Fraley et al., 2013. Interpersonal and genetic origins of adult attachment styles: a longitudinal study from infancy to early adulthood
77 Personality, identity and psychological transformation
A change of setting can bring out a side of someone we barely knew existed. How fixed was that person's character in the first place? Transformation might involve neglected possibilities or different responses, while something recognisable remains. At what point would we say someone had genuinely become another person?
Further reading Mirjam Stieger et al., 2021. Changing personality traits with the help of a digital personality change intervention
78 Status, dominance and social hierarchies
Why does recognition matter when our material needs are already met? Status offers belonging as well as influence, and people compete for the things their communities admire. Looking at who receives prestige can tell us as much about a society's values as about the ambitions of its members.
79 Persuasion, influence and psychological manipulation
Would an attempt to influence you still feel acceptable if its purpose were visible? Could you genuinely refuse? Those questions help locate the boundary between persuasion that expands understanding and manipulation that takes advantage of someone's limited opportunity to reflect.
Further reading Federal Trade Commission, 2022. Bringing Dark Patterns to Light
80 The psychology of evil and human cruelty
Ordinary people can become capable of extraordinary cruelty. How? Imagining a separate class of monsters keeps the disturbing part at a comfortable distance. Understanding the part played by institutions and circumstances might help prevent harm, while leaving people responsible for the choices they make.
Further reading Stanley Milgram, 1963. Behavioral Study of Obedience (abstract)
Further reading S. Alexander Haslam and Stephen D. Reicher, 2012. Contesting the “Nature” of Conformity: What Milgram and Zimbardo’s Studies Really Show
81 Parenting, childhood development and human potential
A parent can create conditions in which a child is more likely to flourish, but cannot guarantee the outcome. How much should they try to shape? Supporting a child's capabilities and security also means leaving room for a life the parent would never have chosen.
Further reading National Academies of Sciences, Engineering, and Medicine, 2016. Parenting Matters: Supporting Parents of Children Ages 0–8
82 Sexuality, desire and intimate relationships
Desire, intimacy and identity fit together differently across people's lives. Biology alone cannot explain all that variety; culture and personal meaning matter too. How can we remain curious about those differences while taking consent seriously and allowing people to define their own boundaries?
Further reading Andrea Ganna et al., 2019. Large-scale GWAS reveals insights into the genetic architecture of same-sex sexual behavior
83 The psychological foundations of religion and ideology
Losing a belief can feel like losing a community or part of yourself. Religion and ideology offer moral direction and belonging alongside explanations of the world. That helps explain why a factual disagreement can become so personal, and why changing one's mind may carry costs an argument barely touches.
Further reading Benjamin Grant Purzycki et al., 2016. Moralistic gods, supernatural punishment and the expansion of human sociality
84 The evolutionary origins of cooperation and altruism
Why help someone who can never repay you? Reciprocity explains some cooperation, but affection and shared commitments invite other accounts. Tracing how altruism became possible is fascinating in its own right. Whether we ought to be generous remains a further question.
Further reading Martin A. Nowak, 2006. Five rules for the evolution of cooperation
85 Mental health, emotional resilience and psychological suffering
Similar events can leave people with very different emotional lives. Biology and relationships matter, as does the meaning someone gives to what happened. How can we understand resilience without making suffering a personal failure? Sometimes the person needs support, and sometimes the conditions around them need to change too.
Further reading World Health Organization, 2022. World mental health report: Transforming mental health for all
86 Discipline, motivation and habit formation
Knowing what matters rarely makes a habit change by itself. The routine and the immediate reward may keep winning. What would happen if we spent less effort demanding willpower and more effort arranging a life in which the actions we value are easier to repeat?
87 Intellectual humility and personal blind spots
What would change your mind? It sounds simple until you try to answer it about a belief that matters to you. Intellectual humility needs room for surprise, particularly from objections we dislike. How do we find assumptions we do not yet know we are making?
Further reading Mark R. Leary et al., 2017. Cognitive and Interpersonal Features of Intellectual Humility
88 Making major life decisions under uncertainty
Some uncertainty yields to research. Some yields only to living through a decision. How do you know when you have learned enough to act? Waiting may preserve a possibility for a while, but it can also close one without ever feeling like a choice.
Further reading L. A. Paul; original 2014, linked US hardback 2015. Transformative Experience (publisher description)
89 Career reinvention, ambition and personal optionality
An ambition can outlive the reasons you first cared about it. When should you persist, and when should you reconsider what success means? Reinventing a career involves security and identity as well as opportunity. Letting go can be hard when a goal has become part of your account of who you are.
90 Emerging technologies and future industries
A new industry may emerge where several technologies meet. Robotics could develop differently as AI, materials or biotechnology advance. Which combinations remove a real bottleneck? And what else would have to change before an impressive invention became something people could routinely use?
Further reading OECD, 2025. OECD Science, Technology and Innovation Outlook 2025: Driving Change in a Shifting Landscape
91 Cybersecurity, digital warfare and technological vulnerability
Much of daily life rests on digital systems working as expected. Their dependencies become visible when something fails. What would resilience look like if we assumed protection would sometimes break? Limiting damage and recovering essential functions might then deserve as much thought as keeping an attacker out.
Further reading National Institute of Standards and Technology, 2024. The NIST Cybersecurity Framework (CSF) 2.0
92 Real estate, cities and the economics of location
A neighbourhood's value depends partly on what surrounds it: access, institutions and the expectations people share. Much of that value is created collectively. As a city becomes more successful, who should benefit, and why do some places attract investment while others struggle?
93 Taxation, citizenship and personal sovereignty
Work in one country, live in another and hold assets in a third. What does citizenship mean in that life? Mobility complicates the relationship between public benefits and the contributions that support them. How should rights and obligations fit together when a person's life crosses several jurisdictions?
Further reading OECD. Tax residency; jurisdiction-specific guidance last updated 7 April 2026; accessed 14 October 2026.
94 Nutrition, metabolic health and the science of diet
Eating well has to fit a whole life, including culture, pleasure and practical constraints. The science can be hard to interpret: an association or plausible mechanism may not establish a reliable effect. How do we build a useful understanding without assuming that every body or eating pattern is interchangeable?
95 Exercise, physical performance and human optimisation
You can become stronger, more skilled or able to go further. Which improvement matters to you, and why? Physical development can be satisfying in itself. It also raises the question of how to pursue progress while leaving room for enjoyment, recovery and a life that can sustain it.
Further reading World Health Organization, 2020. WHO guidelines on physical activity and sedentary behaviour
96 Sleep, cognition and brain performance
Every day, an active mind gives up waking awareness for hours. Why does it need to? Sleep becomes strange when we stop taking it for granted. Its connections with memory and emotion invite biological questions, while the conditions that allow someone to rest raise social ones.
Further reading Björn Rasch and Jan Born, 2013. About sleep’s role in memory
97 Creativity, aesthetics and the meaning of beauty
A melody can move you before you have any idea why. How do perception, expectation and memory combine to make something beautiful? Understanding how a work achieves its effect might diminish the mystery, or give us another way to appreciate it.
Further reading Edward A. Vessel, G. Gabrielle Starr and Nava Rubin, 2012. The brain on art: intense aesthetic experience activates the default mode network
98 Literature, film and storytelling as examinations of humanity
A fictional life can let us feel the weight of a choice that an argument merely describes. What do we learn by inhabiting another person's loyalties and consequences? Stories can make complexity emotionally intelligible, though their power to persuade can also conceal how much they have simplified.
Further reading David Comer Kidd and Emanuele Castano, 2013. Reading literary fiction improves theory of mind
Further reading Maria Eugenia Panero et al., 2016. Does reading a single passage of literary fiction really improve theory of mind? An attempt at replication
99 Language, concepts and the limits of thought
A new concept can make something visible that was there all along. Could changing our vocabulary reorganise an entire field of questions? Language gives us distinctions to think with, even if we cannot assume that it sets the absolute boundaries of thought.
Further reading Jonathan Winawer et al., 2007. Russian blues reveal effects of language on color discrimination
100 Constructing a personal philosophy of life
How should you live, given limited time and so much uncertainty? A personal philosophy connects what you believe with what you are prepared to commit to. Can it guide the choices you actually face and still leave room to grow? Principles earn their place through the life they help you lead.
Further reading Aristotle, fourth century BCE; W. D. Ross translation. Nicomachean Ethics, Book I
Further reading Epictetus, compiled by Arrian, second century CE; Elizabeth Carter translation. The Enchiridion