# How to Make a Human Being: A Body of Evidence

Christopher Potter

A startling investigation of what it means to be human.Human beings know how to make machines. But what kind of machine is a human being? And could we ever make one?In order to answer these questions, other questions get in the way:What is it like to be a human being?What is it like to be some other kind of animal?What is reality?What is consciousness?Is there a God?What is love?Why live?The questions proliferate.But all these questions can be viewed as facets of a single question:What is science?In ‘How To Make a Human Being’ Christopher Potter shows how, at every scale of description, human beings escape the net of scientific reductionism. What it is to be human can be glimpsed in the details: in the opening of a window, in a shared joke. But cannot be caught by any reductive scientific description.

## Copyright

Fourth Estate

An imprint of HarperCollinsPublishers 77–85 Fulham Palace Road, Hammersmith, London W6 8JB

www.4thestate.co.uk

First published in Great Britain by Fourth Estate in 2014

Copyright © Christopher Potter 2014

Christopher Potter asserts the moral right to be identified as the author of this work

A catalogue record for this book is available from the British Library

All rights reserved under International and Pan-American Copyright Conventions. By payment of the required fees, you have been granted the non-exclusive, non-transferable right to access and read the text of this e-book on screen. No part of this text may be reproduced, transmitted, down-loaded, decompiled, reverse engineered, or stored in or introduced into any information storage and retrieval system, in any form or by any means, whether electronic or mechanical, now known or hereinafter invented, without the express written permission of HarperCollins.

Source ISBN: 9780007447794

Ebook Edition © MARCH 2014 ISBN: 9780007447800

Version: 2015-02-02

For Peter

Contents

Cover

Title Page

Copyright

Dedication

PART ONE: Materials and Instructions

Section 1: Getting started

Section 2: What can the matter be?

Section 3: Taking sides

Section 4: Nothing → something → everything

Section 5: What is science?

Section 6: What is the universe?

Section 7: Evidence for the existence of an external world

Section 8: Evidence against the existence of an external world

Section 9: On time

Section 10: On things

Section 11: Starting again

PART TWO: Animating the Doll

Section 1: Matter → meat

Section 2: Making babies

Section 3: On consciousness

Section 4: On the self

Section 5: Meat → mind

Section 6: On perception

Section 7: On free will

Section 8: On behaviour

Section 9: There is always something missing

Section 10: When the gene is no longer enough

Section 11: On tools and human evolution

Section 12: Being rather than making

PART THREE: On Being Human

Section 1: On culture

Section 2: On the relationship between human beings and nature

Section 3: On the relationship between human beings and other animals

Section 4: On the relationship between human beings and other human beings

Section 5: On love

Section 6: On doing the right thing

Section 7: On the difficulty of being

Section 8: On dreams and doing nothing

Section 9: On memory

Section 10: On faith, belief and truth

Section 11: On God

Section 12: On eternity

Section 13: On death

Section 14: On humility

Footnotes

Select bibliography

Index of names

By the same author

About the Publisher

PART ONE

What’s the matter?

The opening words of Coriolanus

## SECTION 1. Getting started

1 | Clearly one way to make a human being is to start by making a universe of the right kind. But out of what material, and what conditions?

## SECTION 2. What can the matter be?

There is only one sort of stuff, namely matter – the physical stuff of physics, chemistry and physiology.

Daniel Dennett, philosopher

There is only one kind of stuff in the universe and it is physical. Out of this stuff come minds, beauty, emotions, moral values – in short the full gamut of phenomena that gives richness to human life.

Julian Baggini, philosopher

The laws of physics have conspired to make the collisions of atoms produce plants, kangaroos, insects and us.

Richard Dawkins, biologist

1 | All of reality is nothing more than an arrangement of particles. Our physical and mental life must be made out of particles because there is nothing else. Everything comes down to what the particles are. Work that out and you know all there is to know.

2 | Bishop Berkeley’s1 strongest claims to whatever fame is still attached to his name are his theory of immaterialism – that material objects exist only because there is a mind that perceives them – and his ‘proof’ that there is nothing the world can be made out of. If the world is material and made out of some type of smallest thing, some particle, then whatever that smallest particle is, it must extend into space, since it is in the nature of all material things that they take up room. Furthermore it must be possible in principle, even if we don’t know how to do it in practice, to divide these particles into smaller particles; because however small any particle might be, we can imagine some part of it taking up less space. And so the search to find the smallest particles out of which the fabric of the material world is woven must be endless. The argument does not necessarily claim the world as spirit, so much as point out that a material world must be some kind of an illusion: not that the world does not exist, but that it is not what it appears it be.

There is no there there.

Gertrude Stein (1874–1946), poet and novelist 2

I have followed the materialist story of our origin – nay, of my origin. But I have grave misgivings. As an act of faith it requires so much.

John Eccles (1903–97), neurophysiologist

I said that the latest advances in science seemed to have made materialism untenable, and that the most likely outcome was still the eternal life of the soul and reunion beyond the grave.

Marcel – Proust’s narrator – to his grandmother in Remembrance of Things Past

## SECTION 3. Taking sides

1 | Ever since Newton’s time, when billiards was in vogue, science has tried to reduce the world to balls hitting one another: billiard ball atoms, billiard ball planets, billiard ball stars. For those of us who have fought shy of games ever since schooldays, it is sometimes hard to accept that ball games really are the be all and end all of existence. Even on those days when I know – or is it fear? – that all that there is can be reduced to particles, I am dispirited. I feel as I did at school: I know that materialism is the manlier choice, but it just isn’t me.

There are days when the world seems to be split into two teams and I do not know which side to be on. Brian Greene, Richard Dawkins (captain), Daniel Dennett, Dr Johnson, Thomas Jefferson, Lucretius, Stephen Hawking, Aristotle, David Attenborough and Thomas Huxley are on one side.[1] Marcel Proust, Leo Tolstoy, William James (captain), Marilynne Robinson, John Keats, Rowan Williams, Karen Armstrong, Plato, William Blake and Emily Dickinson on the other. Dr Johnson and Rowan Williams sometimes play in goal. Proust and Keats invariably call in sick. Darwin and Descartes have been known to show up for either side. Einstein is a popular referee. Confusingly, there are times when it is hard to tell which team even Richard Dawkins or Brian Greene is playing for. But generally Richard Dawkins’s team terrifies me and wins. William James’s team invariably loses, but they don’t seem to care.

On the one side are the materialists: what you see is what you get. The world can be reduced to basic ingredients, and those ingredients are material: they exist, can be weighed and counted, measured and timed. Materialism, reductionism: words that shine with confidence.

On the other side are the idealists, who believe that the physical world is somehow a manifestation of something immaterial. We are the transcendentalists, they cry (‘Give us a T …’). Idealism, transcendentalism: words that sound airy-fairy.

2 | At school I remember games period, lining up, waiting to be chosen, down to the last four, the final humiliation of being the very last hardly averted by the gamesmaster: ‘The rest of you just divide up equally’; then the desperate rush to attach myself to what I hoped was to be the stronger side, wanting to be on the winning team but not wanting to take part, hoping that I might be in goal, left alone to sing hymns to myself while everyone else battled it out at the other end of the pitch.

3 | I remember, too, poring over a copy of the Ladybird book of Roundheads and Cavaliers, puzzled. Clearly, my heart told me, it was better to be a Cavalier: the clothes, the hair, the colours! And yet rationally I knew that to be a Roundhead was the right, the moral choice.[2]

4 | There are these days:

I am satisfied and sufficiently occupied with the things which are, without tormenting or troubling myself about those which may indeed be, but of which I have no evidence.

Thomas Jefferson (1743–1826), American founding father

There was no room for the mystical, the mysterious, the illusory in his temperament. Anything that did not stand the test of practical experience or the scrutiny of analysis he rejected as an optical illusion, some kind of interplay of light and colour on his retina, or else a phenomenon that still lay beyond the reach of experience. There was in him nothing of the dilettante who loves to delve into the realm of the fanciful and idle speculation about the wonders and marvels that lie a thousand years into the future. He took a firm stand on this side of the threshold of the mysterious, free equally of a childlike credulity and the doubts of the over-sophisticated, and patiently reserved judgment until the evidence came in and provided a key to the mystery.

Konstantin Levin in Tolstoy’s Anna Karenina

5 | There are also these days:

i Days when I feel like Fotherington-Thomas[3] – ‘who sa hello clouds hello sky’, and who ‘like all goody-goodies he believe in fairies father xmas peter pan etc and unlike most boys they are kind to their sisters’ – days when ‘I simply don’t care a row of buttons whether it was a goal or not nature alone is beautiful.’

ii Or like the evolutionary biologist Richard Lewontin when he writes that science is ‘filled with the violence, voyeurism, and tumescence of male adolescent fantasy. Scientists “wrestle” with an always female nature, to “wrest from her the truth”, or “to reveal her secrets”. They make “war” on diseases and “conquer” them. Good science is “hard” science; bad science (like the refuge of so many women, psychology) is “soft” science, and molecular biology, like physics, is characterised by “hard inference”. The method of science is largely reductionist, taking Descartes’s clock metaphor as a basis for tearing the complex world into small bits and pieces to understand it, much as the archetypal small boy takes apart the real clock to see what makes it tick.’

6 | But there are days, perhaps most days, when it is not clear which side to be on.

7 | When told of Bishop Berkeley’s fashionable new philosophy of immaterialism Dr Johnson[4] said, ‘I refute him thus,’ and kicked a rock. I’ve always had a soft spot for Dr Johnson. He preferred people to places, and loved his cats. When he first read Hamlet he was so frightened by the ghost of Hamlet’s father that he rushed outside in order to have living people about him. According to his friend Jonas Hanway, he was ‘a hardened and shameless tea-drinker’. He devoted himself to conversation. He was terrified of eternal damnation. As an entertainment to his guests, he pulled up his tailcoats to form a pouch and jumped about in imitation of a kangaroo. When he was four years old his mother called him a puppy and he said to her: ‘Do you know what they call a puppy’s mother?’ He rolled down a hill in Lincolnshire when he was in his fifties. He leapt a wall in his seventies. When William Hogarth met him he mistook him for an idiot, ‘shaking, twitching, pock-marked, half-blind and distinctly careless about his dress’. He compiled a dictionary of the English language from scratch, and although after two years he got stuck on the word ‘carry’, he persevered. In 1755, nine years after he had begun, the dictionary that made his name was published in two volumes, each volume weighing in at fourteen pounds. He said he had tried studying philosophy, ‘but cheerfulness was always breaking in’. In that unsubtle, if entertaining, gesture Johnson kicks more than a rock; he directs a kick in the general direction of all philosophical argument that goes against common sense. And it’s common sense, the gesture insists, that makes us human, and not some illusive philosophical argument. Dr Johnson kicked His Grace into the sidelines of history.

8 | And yet, if Dr Johnson has about him the no-nonsense mien of the Roundhead, it is surely as a shield to protect the heart of a Cavalier. Tolstoy’s Levin could hardly be less like Dr Johnson (for one thing he is fictional), but he too combines traits of both Cavalier and Roundhead, idealist and materialist. Levin wants to believe but cannot. Yet it is his unbelief that tortures him. As a child and adolescent he had turned to Christianity to try to address the questions of life: ‘whence it came, wherefore, why, and what it was’. Finding no answers there, he turned as a young man to science: ‘involuntarily, unconsciously, he now sought in every book, in every conversation, in every person, a connection with these questions and their resolutions’. By his mid-thirties he found that even scientific answers no longer satisfied him: ‘he became convinced that those who shared the same views with him simply dismissed the questions which he felt he could not live without answering … He was in painful discord with himself and strained all the forces of his soul to get out of it … He read and pondered, and the more he read and pondered, the further he felt himself from the goal he was pursuing … Convinced that he would not find an answer in the materialists, he reread, or read for the first time, Plato, and Spinoza, Kant, Schelling, Hegel and Schopenhauer – the philosophers who gave a non-materialistic explanation of life.’ But nor does philosophy bring consolation: ‘Following the given definition of vague words such as spirit, will, freedom, substance … he seemed to understand something. But he had only to forget the artificial train of thought and refer back to life itself … and suddenly the whole edifice would collapse like a house of cards.’

But Levin did not shoot himself or hang himself and went on living … not knowing and not seeing any possibility of knowing what he was and why he was living in the world, tormented by this ignorance … and at the same time firmly laying down his own particular, definite path in life.

Leo Tolstoy (1828–1910), Anna Karenina

## SECTION 4. Nothing → something → everything

1 | Physicists don’t pack up just because some philosopher or other points out that what they are doing is paradoxical. Particle physicists accept that elementary particles are not required to extend into space, nor to exist. If that means redefining what it means to exist, then so be it.

2 | In the main, scientists working at the coalface have little time for the fine distinctions made by philosophers. They are interested in what is in front of them. They are Dr Johnson not Bishop Berkeley, Romeo not Friar Laurence.

3 | Philosophy is adversity’s sweet milk, says Friar Laurence. Hang up philosophy! says Romeo in reply. Unless philosophy can make a Juliet, Displant a town, reverse a prince’s doom, It helps not, it prevails not: talk no more.

Philosophy is dead.

Stephen Hawking, on the first page of his book The Grand Design

Philosophy is to science what pornography is to sex.

Steve Jones, biologist

Philosophers keep out. Work in progress.

A notice pinned to the laboratory door of the physicist Niels Bohr (1885–1962)

If you ask in how many cases in the past has a philosopher successfully solved a problem, as far as we can say there are no cases.

Francis Crick (1916–2004), biologist

4 | In refutation of Zeno’s paradox,[1] Diogenes got up and walked across the room.

To study Metaphysics as they have always been studied appears to me to be like puzzling at astronomy without mechanics.

Charles Darwin (1809–82), in his notebook

Sometimes he thought sadly to himself, ‘Why?’ and sometimes he thought, ‘Wherefore?’ and sometimes he thought, ‘Inasmuch as which?’ – and sometimes he didn’t quite know what he was thinking about.

Eeyore the philosopher in A.A. Milne’s Winnie the Pooh

Philosophers have been profoundly wrong in almost every question under the sun over the last 2,000 years. You should never listen to the answers of philosophers, but you should listen to their questions.

Christof Koch, neuroscientist

Philosophers will tell you the whole idea of science is just a subset of philosophy.

David Rothenberg, philosopher

5 | Philosophy used to matter more. Of Plato’s five kinds of imagined regimes, the greatest – named Kallipolis – was ruled by philosopher kings.[2] Socrates had to die because philosophy was seen as a threat to society. These days philosophy matters only to philosophers.

Philosophy is the highest, the worthiest, of human endeavours.

Slavoj Žižek, philosopher

6 | Scientists have a habit of dismissing the questions they don’t want to answer. They call them philosophical. For many scientists, philosophy is a step too close to theology. Scientists eschew philosophy for logic or even for just plain common sense.

The whole of science is nothing more than a refinement of everyday thinking.

Albert Einstein (1879–1955)

It is generally thought that common sense is practical. It is practical only in a short-term view. Common sense declares that it is foolish to bite the hand that feeds you. But it is foolish only up to the moment when you realize that you might be fed very much better.

John Berger, writer and art critic

7 | If, as philosophers have concluded, there is nothing that the universe can be made out of, scientists have wondered what that nothing might be.

8 | Science, philosophy and religion have this in common: that they all must account for how nothing became something. Philosophers have worried for centuries about the nature of substance and of nothingness. Religions have their various creation myths. Science too tells its own creation story. The triumph of particle physics is that it so nearly explains how nothing became everything.

Why is there something rather than nothing?

Gottfried Leibniz (1646–1716), philosopher and mathematician

All things are born of nothing and are borne onwards to infinity.

Blaise Pascal (1623–62), philosopher and mathematician

9 | If only we knew exactly how the story began. If only we could say, ‘Once upon a time’ and know what follows.

10 | An ancient Greek cosmology has the world created out of a pre-existing condition called chaos. Kaos is not emptiness but formlessness. It was the world before there were things in it. The word nothing, like some fossil of ancient thought, still retains that original concept of no thing. The universe emerged when Logos, meaning variously form, knowledge and word, came into contact with Kaos. Out of their union comes Cosmos (beauty or order, as in cosmetics, which bring order to the face). The opening words of St John’s gospel repeat this ancient prescription: In the beginning was the Word. In the original Greek the word translated as ‘word’ is Logos. And in Genesis we find God creating nature by separating out from chaos what then become things with names. Naming is a process of separating out, and the first step in any scientific investigation of the world. Before explanation must come the naming of parts. The idea of nothing as emptiness came later. That the universe was created out of emptiness, ex nihilo, is a radical departure from how creation was envisaged by certain ancient Greek philosophers, and was an interpretation imposed on the Biblical story by medieval scholars.

11 | Our current best modern-day creation stories are variants of the Big Bang theory, a mathematical description of the universe coaxed out of the equations of general relativity. Even though they were his equations, Einstein at first denied the Big Bang. Later he changed his mind.

The most beautiful and satisfactory explanation of creation to which I have ever listened.

Einstein, of an exposition of the Big Bang given by its inventor (discoverer?) Georges Lemaître (1894–1966), priest and physicist

12 | All matter can ultimately be reduced to constituent particles – bosons and fermions – that are the excitations of various types of energetic field. At the Big Bang there may have been a single kind of energetic field which, in an expanding universe, evolved into other kinds of energetic field.

Within a trillionth of a trillionth of a trillionth of a second after the Big Bang the universe is a cascade of particles decaying into other particles. Whole eras of the universe passed before it was even a second old.

13 | We know what happened in the first trillionth of a trillionth of a trillionth of a second, but what happened in the beginning?

14 | In the beginning everything was in the same place at the same time. In the beginning the physical world is pure energy, whatever that is. In the beginning the universe is some condition of form, number and energy held in perfect symmetry. It cannot last. The symmetry breaks and becomes a world of asymmetries, imperfections and accidents. The world falls into existence.

The positive energy within matter can be counterbalanced by the negative sink of the all-pervading gravitational field such that the total energy of the universe is potentially nothing; when combined with quantum[3] uncertainty,[4] this allows the possibility that everything is … some quantum fluctuation living on borrowed time. Everything may thus be a quantum fluctuation of nothing.

Frank Close, particle physicist

Zero exists now, it has always existed, and it will always exist. It is the native state of existence. It is what the physicist David Bohm called implicate order. It is the timeless quantum superposition of all universes and all life in an infinite universe. As the most brilliant physicists have long held, a perfect zero is the most ordered state of all, it just isn’t found in the past where time begins. It exists in the future where time ends.

Gevin Giorbran, science writer

15 | Energy leaks out of the vacuum for no reason at all except randomness and the pressure exerted by a sink of infinite negative energy. Overall the universe is nothing at all.

16 | Take matter out of the universe and reality becomes unstable, liable to give birth randomly to new universes. The vacuum is the birthing ground of universes; like the silence of the mystics, a roiling place of visions and madness, of annihilating forces.

17 | In the outer reaches of the universe, as far away from here as it is possible to be, beyond time and space and meaning and matter, nothing was happening. And the nothing was without form, pure potential for becoming, an evanescent yet heaving sea of energy coming into and out of existence. For reasons not yet understood, a bubble of energy that should have burst back into non-existence breaks free with the rage of Achilles from the conditions of the quantum world and sweeps out a universe.

18 | The universe is just one of those things that happens from time to time. Everything that is exists only by happenstance, randomly, out of nothing.

19 | If less is more, is nothing too much?

20 | For now the most widely-agreed-on model that describes how the universe got going is the theory of eternal inflation. An infinite number of ‘bubbles’ arose in an eternally inflating quantum landscape. One of these bubbles became the island universe we call home. An infinite number of other island universes exist in all the possible forms determined by some constraining mathematical model, most popularly string theory.[5] The landscape out of which these island universes emerged is called the multiverse.

21 | Inflation is happening eternally, elsewhere. Our ‘island’ universe inflated briefly. It doubled in size every 10–34 seconds. After about a hundred such doublings it had grown to about the size of a grapefruit, at which point the period of inflation came to an end.[6] Why inflation came to an end locally is not yet known.

I could be bounded in a nutshell, and count myself king of infinite space.

Shakespeare (1564–1616), Hamlet

22 | i You do not need God in order to create a universe, says Stephen Hawking. All you need is gravity, quantum electrodynamics, special and general relativity, M-theory and a few other bits and pieces of physics. But where these ingredients come from remains, for the moment at least, an unanswered question.

ii M-theory (no one can remember what the M stands for) is a formulation of string theory, and a quantum theory of gravity – an abstract and mathematical theory, as yet without physical proof. M-theory describes a multiverse of eleven dimensions in which there may be many island universes like ours, adrift in four dimensions of time and space; and many other kinds of universes adrift in different numbers of dimensions of space, some perhaps with several dimensions of time (whatever that might look like). M-theory describes 10500 different universes.

Consider the most obvious question of all about the initial state of the universe. Why is there an initial state at all?

Lawrence Sklar, philosopher of physics

The desire to find a beginning comes from the idea that everything has the real, solid existence that our minds generally perceive.

Matthieu Ricard and Trinh Xuan Thuan, The Quantum and the Lotus

As far as I can see, such a theory [as the Big Bang] remains entirely outside any metaphysical or religious question. It leaves the materialist free to deny any transcendental Being … For the believer, it removes any attempt at familiarity with God. It is consonant with Isaiah speaking of the hidden God, hidden even in the beginning of the Universe.

Georges Lemaître

23 | In saying that the universe randomly evolved out of some initial energy condition that we don’t yet fully understand, we sweep everything we don’t know about the universe under the carpet. All the unanswered questions about the physical universe get pushed to its horizons, far away from where humans are. The horizons of the universe are the limits of what we can see and what we can understand. The universe disappears over its own horizon, taking with it the laws of nature, forever just out of our reach. For a while, the more we found out about the physical universe the larger it became. But largeness itself has become passé. The universe shows itself to be subtler than mere size. All our creative speculations, even when they harden into theories, merely push the mystery of what we are and where we come from to ever more distant regions of an ever more elusive universe.

## SECTION 5. What is science?

Science (a term in itself inoffensive and of indefinite meaning).

Joseph Conrad (1857–1924), The Secret Agent

That bright-eyed superstition known as infinite human progression.

Terry Eagleton, literary theorist and critic

1 | Life may be messy, but in the physical world there appears to be underlying order. Evidence of this order has encouraged scientists to believe in the existence of physical laws of nature. Why nature should have unifying features is a deep mystery. That physical laws of nature are ultimately reducible to mathematics is an even deeper mystery.[1]

2 | The difference between the ways of science and the ways of other truth-seeking enterprises is that science has a method.

First find what you think might be a solution to a problem, then express it as a mathematical model, then test it.

David Deutsch, physicist

3 | In science, to look is not enough, there needs also to be intervention in order to affirm what it is that is being looked at. A testable theory is required, not just mere description, though a description is a start. A theory is proven for as long as it is confirmed in that repeatable process of measurement called experiment. Sometimes we improve our ability to measure and theories are further confirmed, and sometimes theories fail when examined more closely.

If the explanation of physical phenomena were evident in their appearance, empiricism would be true and there would be no need for science as we know it.

David Deutsch

‘We admit the existence of electricity, which we know othing about, why can’t there be a new force, still unknown which …’

‘When electricity was found,’ Levin quietly interrupted, ‘it was merely the discovery of a phenomenon, and it was not known where it came from or what it could do, and centuries passed before people thought of using it. The spiritualists on the contrary, began by saying that tables write to them, and spirits come to them, and only afterwards started saying it was an unknown force.’

Vronsky listened attentively to Levin, as he always listened, evidently interested in his words.

‘Yes, but the spiritualists say: now we don’t know what this force is, but the force exists, and these are the conditions under which it acts. Let the scientist find out what constitutes this force. No, I don’t see why it can’t be a force, if it …’

‘Because,’ Levin interrupted again, ‘with electricity, each time you rub resin against wool, a certain phenomenon manifests itself, while here it’s not the same each time, and therefore it’s not a natural phenomenon.’

…

‘I think,’ he continued, ‘that this attempt by spiritualists to explain their wonder by some new force is a most unfortunate one. They speak directly about spiritual force and want to subject it to material experiment.’

They were all waiting for him to finish, and he felt it.

‘And I think that you’d make an excellent medium,’ said Countess Nordston, ‘there’s something ecstatic in you.’

Leo Tolstoy, Anna Karenina

4 | The astronomer Nicolaus Copernicus (1473–1543) wondered if there might be some sort of inclination in matter that causes matter to be drawn to itself. But his was a vague poetic notion; it didn’t have what elevates Newton’s description – of what was later named gravity – to the level of theory. Newton writes in mathematics how the force works even as he fails to tell us what it is. Since it acts at a distance without any visible means of action, Newton’s gravity has no material existence, for which lack the theory was criticised by followers of Descartes, who believed that physical actions must result only from physical causes. But in physics mathematics trumps material means. The theory works, and that is enough, particularly when the theory is as encompassing as this one: explaining as it does both why an apple falls to earth and why the earth falls perpetually towards the sun.

A force without materiality looks indistinguishable from magic, but mathematics is what makes the reality of gravity testable. The lack of visible means was first criticised, then overlooked, and finally forgotten about.

If they don’t depend on true evidence, scientists are no better than gossips.

Penelope Fitzgerald (1916–2000), The Gate of Angels

5 | Science is an attempt to make knowledge collective. Science separates out from the world what can be repeated. Scientific experiments are repeatable (in theory at least) by anyone, ideally not just any competent human but any competent alien. Art is collective evidence of shared experience too, but science goes further; its knowledge means to be universal, not ‘merely’ human.

6 | Science searches for evidence of stability in the world out there. At one time we saw stability in the so-called fixed stars, until it was discovered that they are not fixed, just moving very slowly relative to each other, and only appear fixed because they are so far away. We used to think space and time were immutable, until Einstein showed otherwise. Today we begin to wonder if even the speed of light is a constant.

7 | Science organises the meaning of the world into what it is hoped are irreducible statements called the laws of nature, but every seemingly irreducible statement is doomed ultimately to be replaced by another attempt at the irreducible; and so science makes progress. There are no truly fundamental theories in science. Something more fundamental always comes along, eventually. ‘Fundamental’ theories are the theories that are currently most effective, but they are never complete. And never being truly fundamental, we cannot know if they are ever truly universal. In science, to understand more deeply is to get under what it is that is currently being stood on. What science stands on is continually being replaced by lower floors.

8 | Science has this particular strength, that theories are only overthrown when a new theory encompasses more phenomena than the previous theory encompassed. In this sense, old theories do not die, a new theory reveals the limits within which the old theory was, and still is, effective; but crucially the new theory goes beyond those boundaries into territory in which the old theory fails. Some scientists say that Newtonian physics was shown to be incorrect by Einstein’s theories of relativity, others that Einstein showed the limits within which Newton is true.

9 | Truth in science is a comparative entity: there is always the possibility of truer, but what is truer may sometimes – not always, by any means – look completely different from what was almost as true. In order to encompass all that has gone before, a new theory may – occasionally – be forced to do so by completely refashioning the nature of reality.

10 | Einstein twice had to rearrange the material world in order to satisfy the demands of mathematics. In order to take James Clerk Maxwell’s equations seriously – they describe electric and magnetic fields and their relationship to each other – he showed that it was necessary to change our thinking about what motion is. The invariant nature of light, he asserted, sets a limit on how fast things can move. In our everyday world we assume that however fast we travel, someone or something might conceivably travel faster; but this is not how things are, only how they appear to be at the relatively slow speeds (compared to the speed of light) of everyday human life. The classical world of Newtonian mechanics is limited, and Einstein shows where and why. No doubt Einstein’s assumption about light will prove to be an approximation too, but we do not yet understand how. When we do we will call it progress.

Einstein’s assumption upheaved time and space into a conjunction that Nabokov called ‘that hideous hybrid whose very hyphen looks phoney’. ‘Space-time’ more accurately describes the nature of reality than space and time taken separately. And yet, puzzlingly, we do not experience the space-time continuum. We believe we experience space and time separately. But since we do not have sense organs devoted to experiencing either space or time, perhaps what we experience comes from habit or is a delusion. In any case, all our best measurements show that space-time is a better approximation to reality than Newton’s theatre set in space and time.

In 1900, Max Planck solved a seemingly intractable problem in physics by breaking light into small packets. He effected a revolution in science even though he did not personally believe that these small packets – later named quanta – were anything more than a mathematical trick. Einstein took quanta seriously, and effectively invented quantum physics (aka quantum mechanics).

11 | The magnetic moment of an electron has been measured to eleven decimal places, and is still in agreement with what quantum mechanics predicts it should be. There is no guarantee that in the twelfth decimal place some new theory might not be required.

Astronomers have been monitoring the orbits of one double neutron star system – known as PSR 1916+16 – for around forty years. The emission of Einstein’s predicted gravitational waves from this system has been confirmed through a very gradual shortening of the star’s orbital period, and there has been agreement between the signals received from space and the overall prediction of Einstein’s theory to an astonishing fourteen decimal places.

Roger Penrose, mathematical physicist and philosopher

In the fifteenth decimal place, who knows?

12 | Finer measurement requires the invention of finer measuring instruments. Finer measurements lead to better theories. Out of better theories come subtler experiments. Progress is what results from the positive feedback of theory, experiment, and tool-making.

Very little in nature is detectable by unaided human senses. Most of what happens is too fast or too slow, too big or too small, or too remote, or hidden behind opaque barriers, or operates on principles too different from anything that influenced our evolution. But in some cases we can arrange for such phenomena to become perceptible, via scientific instruments.

David Deutsch

13 | Science goes in search of what is truer. If that means science goes in search of the truth, it does not logically follow that the truth exists, nor, if it does exist, that the truth can ever be reached. Even if we did believe that some ultimate truth exists, we can have no idea what it might look like.

14 | When Copernicus first wondered if the sun, and not the earth, was at the centre of things, he stumbled on what was to become a powerful driving force of the scientific method: that human beings do not occupy any position of privilege in the universe. Scientific progress is the attempt – repeated over and over again – to remove human beings from the centre of things. We are not at the centre of anything, is what the scientific method continually reminds us.

15 | The centre is a place of privileged perspective. If science is to find universal laws, then by their very nature universal laws cannot be privileged, or they would not be universal; and if they are not universal – no matter how grand they are – they are provincial.

16 | In order to uphold its own central tenet that humans are not at the centre of anything, the scientific method itself must be universal. It must have been discovered elsewhere by other intelligences across the universe. Science needs aliens. The more aliens the better. That no aliens have so far stepped forward might be seen as a blow to materialism.

We can be sure that any intelligent beings inhabiting those planets will measure the same inverse square law.

John Gribbin, science writer

It will be a great day in the history of science if we sometime discover a damp shadow elsewhere in the universe where a fungus has sprouted. And here we are, a gaudy efflorescence of consciousness, staggeringly improbable in light of everything we know of the reality that contains us.

Marilynne Robinson, Absence of Mind

17 | If aliens do not exist, the whole question of what kind of reality science describes is called into question. So long as aliens do not exist, what we are as humans in the universe remains an open question. So long as aliens do not exist, human beings are the aliens in the scientific woodpile.[2]

18 | There is nothing inevitable about the way the scientific method has developed on earth. Nor is it inevitable that human beings should have stumbled on the scientific method at all. Many civilisations have come and gone with very different cosmologies. And if not inevitable here, there may be many other worlds where there is sentient life but no scientific understanding. Presumably there are cosmologies out there, as there have been here on earth, that come at the universe from quite a different perspective. Why should other life forms care about intelligence most of all? They may have discovered other motors of the universe. Scientific progress is directly related to our ability to imagine what alien life might be.[3]

Our conceptual model of space and time has proven to be extremely successful – to such an extent that we may even find it difficult to imagine other ways of organising our thoughts and experience – but it isn’t logically inevitable.

Marilynne Robinson, novelist and essayist

[Theories] about the nature of the world become frameworks within which we live. And so they constrain what we think is possible, what we think is real.

Max Velmans, professor of psychology

19 | Scientific theories are frameworks that attempt to contain the world. But these frameworks are never more than detailed models, and a model is not the thing itself. Any knowledge about something is not the thing itself either. The only complete model of the universe would be the universe.

There is nothing more deceptive than an obvious fact.

Sir Arthur Conan Doyle (1859–1930), ‘The Boscombe Valley Mystery’

20 | Scientific facts are attached to theories that are part of a methodology that continually changes the limits within which they can be regarded as true. Facts are always embedded in theory, and theories come and go. There are no facts without theories. What we take to be facts may not be facts for other intelligent, questioning life forms. We can know the facts, but why they mean anything is another matter.

21 | It is far from clear that there are universal laws,[4] but the pursuit of them has resulted in what we call progress, the outward and visible evidence of which is the material world we live in.

22 | The scientific fundamentalist takes home with him his belief that laws of nature actually exist. The more open-minded scientist understands that science is a kind of game whose rules only need apply in the laboratory or at the desk.

23 | Science is a mode of enquiry, not the last word. There are different world views, and they do not have to be commensurate, or agree with each other. And you don’t have to say one is better than another in all domains. But clearly if you want to build a rocket you will turn to physics, not theology.[5]

And why, after all, may not the world be so complex as to consist of many interpenetrating spheres of reality, which we can then approach … by using different conceptions and assuming different attitudes.

William James (1842–1910), The Varieties of Religious Experience

24 | There are new theories to come that are beyond the reach of current technologies and of our current imaginations. In order to make progress sometimes a technological leap will come first, as it did when the telescope turned from plaything into scientific measuring instrument. Sometimes experiment comes last of all, as it did when Einstein re-imagined gravity as the geometry of space-time. He spent ten years working out the mathematics, leaving it to others to prove by experiment that gravity was indeed how he conceived it to be. When Einstein was asked what his response would be if experiment were to prove his theory false, he said he would feel sorry for the dear Lord.

25 | Experiments are generally hard to perform and require determination. No one would perform an experiment without already having some idea of what they are looking for.

Every brilliant experiment, like every great work of art, begins with an act of the imagination.

Jonah Lehrer, writer

26 | For there to be progress in science there has to be some kind of understanding that comes in advance of the finding out: intuition. The history of science is necessarily full of instances in which insight comes first, ahead of proof in observation and theory. Where does, where can that insight come from? There must be various conduits of the truth if imagination sometimes gets there first.

In science the leap of imagination must be of the right kind and not too great a leap. Mediums and other sensitives also claim the ability to see ahead of the material evidence, but their methods fail when exposed to scientific, repetitive investigation. Their evidence is personal and anecdotal, not public and repeatable as science demands.

27 | On the radio I hear the announcer describe the discovery of new planetary system as ‘a rather wonderful poetic idea’. And why not?

28 | In a purely material world the immaterial is what we don’t yet understand materially; a dwindling pile in the to-do basket of science. If we wait too long the ink will have faded and the mystery will have become illegible. How long we are prepared to wait for material answers to material questions tests our faith.

We call the boat back in – Come in, number 87, your time’s up – only to find that the boat is too far out, and anyway, if we but knew it, the boat long ago rotted away and sank without trace.

29 | We don’t know what Nature is. There is that sifted-out part of Nature we call the material world, that ongoing conversation between science and the world, and then there is the world itself, in the largest sense, in which we are embedded. Most of us, most of the time, confuse the material world with the real world, whatever that is.

The scientific method sieves out the material world. The question is left open whether or not there will be anything left in the sieve afterwards, or indeed, if there is an afterwards. It seems increasingly likely that science may at best describe its own limitations, and not ‘everything’, as is sometimes predicted by its fundamentalists.

‘Freddy,[6] I’m told that there are left-overs in the larder. Have you any idea what to do with left-overs?’

‘You don’t have to do anything with them. They’re left over from whatever was done to them before.’

His father smiled and sighed.

Penelope Fitzgerald, The Gate of Angels

30 | Materialism describes a world made out of logic and things that move. If it cannot be measured by a clock and a ruler, it lies outside scientific enquiry. That the whole world is capable of being measured requires faith, and there are days when my faith falters.