Natural Science: Scope | Quomodo Scimus : IBTOK

areas of knowledge - natural science

Scope of Natural Science

What does natural science claim to know - and where does that claim stop?

Thirteen point eight billion years

THE PROVOCATION

The James Webb Space Telescope was proposed in 1996, built over twenty-five years by thousands of engineers and scientists across fourteen countries, launched on Christmas Day 2021, and deployed one million miles from Earth at a point in space called L2, where it cannot be serviced if anything goes wrong. In early 2023, it returned images of light that left its source 13.8 billion years ago - from the first few hundred million years after the Big Bang, a period astronomers call cosmic dawn. Watch the short film below, made by the team who documented the telescope's creation.

Cosmic Dawn - NASA

Filmed over twenty-five years, this documentary follows the James Webb Space Telescope from conception to the moment its first images arrived. You see the engineering failures, the near-cancellations, the blizzards and hurricanes during testing, and finally the engineers watching in silence as light from 13.8 billion years ago appeared on their screens. Two lines from the film are important to this page - "science is a process" and "we have always been surprised by what we see in the sky."

The trailer contains a line worth pausing on: "We have always been surprised by what we see in the sky." This is a description of how natural science works. The instruments are precise, the predictions are mathematical, and the data comes back in ways no one fully anticipated. Carl Sagan called this the method's great strength - it corrects itself, even when the corrections are unwelcome.

But the trailer also shows something the telescope cannot detect. The engineers cry when the first images arrive. They sit in silence. Something happens in those moments - the experience of being a small creature confronted with something 13.8 billion years old. Natural science can tell you the age of that light to within a few million years, the temperature of the plasma it passed through, the rate at which the universe was expanding when it left its source. It cannot tell you what it is like to look at it. That gap - between measuring the universe and experiencing it - is where this page begins.

Big idea 1 - Natural science is not one thing.

The phrase "natural science" suggests a single method applied to a single object. In practice it covers physics, chemistry, biology, ecology, geology, astronomy, and more - disciplines that share some commitments (empirical evidence, peer review, reproducibility) but differ in almost everything else.

Physics looks for universal laws. F = ma applies everywhere in the universe, at all times, without exception. A physicist who found an exception to Newton's third law would not revise the law for that region - they would conclude something had gone wrong with the measurement. The laws are supposed to be exceptionless.

Biology works differently. Evolution explains the history of life on Earth, but it does not generate the kind of universal predictions that physics does. Different populations adapt in different directions; contingency matters; what happened in the past shapes what comes next. When a biologist explains why an organism is built the way it is, the answer is always historical: because of what happened to its ancestors. That is a different kind of explanation from F = ma, and both count as natural science.

Richard Feynman argued that what unifies science is not its conclusions but its attitude: a commitment to doubt, to testing, to revising even well-established claims when the evidence requires it. That description fits physics and biology equally. But the methods those practices use, and the kinds of knowledge they produce, are not the same. A map of what natural science covers needs to show that variation, not flatten it.

Science is unusual among ways of knowing because its claims are not made by individuals - they are made by communities. A result published by one laboratory means little until other laboratories have attempted to replicate it, peer reviewers have interrogated the method, and the finding has survived long enough to be built upon. This is what separates a scientific claim from a personal observation, however careful. The individual scientist can be mistaken, biased, or fraudulent; the community, over time, is designed to catch that. What science produces is not the knowledge of any one knower but knowledge that has passed through a social process of collective scrutiny. That process is slow, contentious, and sometimes wrong - but it is the source of whatever authority scientific claims carry.

Big idea 2 - Science earns its authority by admitting it can be wrong.

The subtitle of Carl Sagan's 1995 book tells you his argument before you open it: Science as a Candle in the Dark. His claim was that the world is full of forces - superstition, motivated reasoning, the pull of believing what we want to believe - that make clear thinking hard, and that science is the best method humans have developed for seeing through them. The method itself builds in error correction, independent of the qualities of the individual scientists using it.

That method rests on a few core commitments. Scientific claims are empirical: grounded in evidence from the observable world, not in authority or revelation. They are intersubjective: open to scrutiny by anyone with the right training and instruments, not dependent on who makes them. And they are provisional: held as the best current account of the evidence, not as final truths. You've already encountered this in your lab work: when you designed an experimental protocol in chemistry, you weren't proving a claim - you were setting up conditions under which a claim could fail. Maths hypothesis testing is the same logic made mathematically precise: a significant result doesn't prove a claim; it shows the data would be surprising if the claim were false. The logic is provisional by design.

The provisional character of scientific knowledge is the hardest to hold on to. It can look like unreliability - if science keeps revising its conclusions, why trust it? Sagan's answer, and Feynman's, was that provisionality is the source of its reliability. A method that cannot revise itself when evidence demands is less trustworthy, not more. The history of science is largely a history of corrections, and the corrections mostly move in one direction: greater precision, wider scope, fewer exceptions. The JWST images in the provocation are a product of provisional knowledge, not a triumph despite it.

Carl Sagan 1996

This is one of Sagan's last major interviews, recorded months before his death in December 1996. He has just been handed a New York Times headline - "Americans Flunk Science" - and what follows is an eight-minute argument about why scientific literacy matters, what science actually is, and what happens to democracies that lose the habit of skeptical thinking. The passage that matters most for this page begins at 2:36. The final thirty seconds are worth waiting for.

Big idea 3 - Objectivity has a blind spot

Science achieves its power partly by adopting what Thomas Nagel calls "the view from nowhere": describing the world as it would appear from no particular standpoint. This is enormously powerful. The law of gravity works the same whether you are in Geneva or on Mars; the laws of thermodynamics do not change depending on who applies them. By removing the perspective of the observer, science makes its findings available to everyone.

But something goes with it. As we saw in Core Lesson 3, Nagel's most discussed argument asks a deceptively simple question: what is it like to be a bat? A bat navigates by echolocation - emitting high-frequency sounds and interpreting the echoes. We can describe this completely in physical terms: the frequency of the sounds, the structure of the bat's auditory system, the neural processes that turn echo patterns into spatial maps. What we cannot describe, Nagel argues, is what it feels like to navigate that way - the subjective, first-person character of that experience.

This is an important weakness. The method that removes perspective cannot, by that removal, capture what it is like to have a perspective. Neuroscience can map the neural correlates of pain, or of recognising a familiar face - but the map is not the experience. Knowing which neurons fire when you see red does not tell you what red looks like from the inside.

This is the point we were making at the top of this page. The JWST can detect light from 13.8 billion years ago and calculate the temperature of the plasma it passed through. What happened in mission control when those images arrived - the silence, the tears - is real, it matters, and it lies outside what the instruments can reach. Whether that is a limitation of current science or a structural feature of what the scientific method is, is the question worth reflecting on when considering the power and limitations of science.

The scope of natural science compared

A knowledge that must answer to the world

Natural science and mathematics share a claim to universality - the laws of thermodynamics hold everywhere, and so does the Pythagorean theorem. But they arrive at that universality differently. Mathematics is a priori: its truths are established by proof alone, without needing to check against the world. Natural science is empirical: however elegant the theory, it answers to experiment. Einstein's general relativity made predictions that had to be tested at the 1919 solar eclipse before the physics community accepted them. A mathematical proof requires no eclipse.

The comparison with history points in a different direction. Both work with evidence and aim at knowledge of what actually exists or occurred. But the kind of explanation they seek is different. Natural science looks for general laws that hold across all instances - the same equations govern a falling feather in Lausanne and a satellite in orbit. History explains particular events in their specific context: why this revolution, in this country, at this moment. The causes of the French Revolution are not a special case of a general law of revolutions. When natural scientists treat human behaviour as data, as epidemiologists did during COVID, they apply scientific logic to material that historians would approach differently - and the two accounts do not always agree on what they found.

Human science sits between the two. Like natural science, it uses empirical methods - surveys, experiments, statistical analysis. Like history, its subject matter is human beings, whose behaviour is shaped by meaning, culture, and conscious intention. When psychology uses controlled trials or economics builds predictive models, they import the methods of natural science into a domain where the objects of study can read the findings and change their behaviour in response. That is a constraint no physicist faces.

The Arts sit furthest from Natural Science’s empirical commitment. Scope of the Arts treats a work as something that does not answer to a prior event or an external test the way an experiment does. A scientific claim can be wrong about the world it describes. An artwork is not making that kind of claim in the first place, so being checked against the world is not the standard it is judged by.

Next: Perspectives in Science

Think further: questions and resources

Feynman argued that what unifies natural science is not a shared method but a shared attitude: organised doubt, including doubt directed at established scientific consensus. Kuhn showed that scientists resist revising well-established theories for decades even when anomalies accumulate. Do these two accounts contradict each other, or describe different phases of the same process?
Nagel argues that a complete physical account of bat echolocation - every neuron, every echo, every signal - still leaves out what it is like to navigate by sonar. Does this mean consciousness is permanently outside the scope of natural science, or does it show only that current neuroscience is incomplete?
Sagan argued that science's willingness to revise conclusions when evidence demands is what distinguishes it from pseudoscience. But the replication crisis of the 2010s revealed that large numbers of peer-reviewed, published findings in psychology and medicine failed to replicate. If the social process of science can be systematically wrong at scale, does this undermine Sagan's claim - or confirm it?
Feynman described science as unified by its attitude of doubt; yet physics explains by universal laws while biology explains by evolutionary history. Is natural science one enterprise with different methods, or several different enterprises that share a name?
Criado Perez showed in Lesson 4 that the absence of women from medical research trials produced findings that failed to apply to half the population. If who does the science shapes what science finds, does this challenge Nagel's "view from nowhere" as an aspiration, or does it simply describe a correctable bias?
The engineers in the Cosmic Dawn film cried when the first JWST images arrived. Sagan described science as being after the way the universe really is, not what makes us feel good. But the response in mission control suggests that scientific knowledge produces experiences - wonder, recognition, something close to grief at the scale of time - that the method itself has no account of. Is that a limitation of natural science's scope, or simply beside the point?

Films
For more see my 10 films for the TOK journey page.

🎬 WATCH — Cosmic Dawn (2023)

NASA.

Filmed over twenty-five years, this documentary follows the James Webb Space Telescope from conception to the moment its first images arrived. The film earns its subject: you see the engineering failures, the near-cancellations, the blizzards and hurricanes during testing, and finally the engineers watching in silence as light from 13.8 billion years ago appeared on their screens. Two lines carry the argument of this page - "science is a process" and "we have always been surprised by what we see in the sky." The full documentary belongs here; the trailer opened this page.

🎬 WATCH — Particle Fever (2013)

Mark Levinson

Six physicists - three theoretical, three experimental - are followed through the years leading to the 2012 announcement that the Higgs boson had been detected at the Large Hadron Collider at CERN. The film is the best available portrait of what science actually looks like from the inside: the years of waiting, the arguments about what the data means, the moment when a number appears on a screen and a room full of people who have spent their careers on a single question find out whether they were right. It connects directly to the social enterprise argument in this page - the Higgs was not discovered by one person but by thousands, and the film shows what that collective process of knowing costs. My students can watch the film here.

🎬 WATCH — My Octopus Teacher (2020)

Pippa Ehrlich & James Reed

A filmmaker spends a year diving daily in a South African kelp forest, returning to the same octopus until something that can only be called a relationship develops. The biology alone is remarkable: the octopus has no centralised brain, distributes its nervous system across eight semi-autonomous arms, and achieves colour vision through photoreceptors in its skin despite being conventionally colourblind. Everything measurable about it can be measured. What it is like to be one is exactly the question Thomas Nagel posed in Big Idea 3 - and the film makes that question impossible to dismiss. It won the Academy Award for Best Documentary Feature in 2021. My students can watch the film here.

🎬 WATCH — Contact (1997)

Robert Zemeckis

Carl Sagan wrote the novel this film is based on, which makes it the closest thing on this page to a primary source. Jodie Foster plays a radio astronomer who receives signals from deep space, decodes them, and eventually travels through a machine she cannot fully explain to a destination she cannot prove she reached. The Senate hearing scene that follows is the film's real subject: what happens when a scientist has a profound experience that meets none of the criteria she has spent her career defending? Contact asks whether the standards of evidence that make science reliable can also make it blind.