Science as Revolution by Sir Paul Nurse

SCIENCE AS REVOLUTION

When we think of revolutions we usually think of major transformations in the spheres of politics, economics, social organisation, or religion, for example the
(slide 1) Russian revolution.

But to these we should add the revolutions brought about by science, both cultural through improved knowledge of the natural world and of ourselves, and through the impact that improved knowledge has had on the development of human civilisation. In this lecture I will argue that science is the most long-lasting revolutionary activity known to humankind. This is because science generates systematic knowledge that stands the test of time. As a result science has long standing consequences for society, acting as a major driver of culture and civilisation, and of changes in the ways that we live. I will illustrate some of these revolutionary advances by tracing the development of science from its first glimmerings in pre-history through to today, arguing that revolutions in science have been of great benefit to humanity, and if science is properly nurtured and used well, it will continue to bring great benefits in the future.



So why is science such a reliable way of generating systematic knowledge of the natural world and of ourselves? It is because of the way that it is done. Science is based on a range of attributes and ways of working, not necessarily unique to science, but which are combined together in science in a very effective way. Science is based on reliable and reproducible observations, generating accurate descriptions of how the natural world behaves; such evidence forms the bedrock of science. The impetus to make observations and to carry out experiments derives from curiosity, natural in children and often persisting at a high level later in the lives of many scientists. From study of these observations and experiments, regularities and patterns can be recognised, which in turn lead to ideas and hypotheses to explain the workings of the world. This requires an attitude of mind that the natural world is in principle explicable, and is not the consequence of capricious supernatural forces.

Explanations in science have predictive power, and particularly in physics the use of mathematics has been key to generating great precision in these predictions. Scientific explanations are often reductionist, that is they look for understanding of natural phenomena at lower levels of organisation, although this should always be in the context of the behaviour of the whole system.

Imagination and intuition are important in generating scientific ideas and hypotheses, that then can be tested with more observations and experiments. This way of working has been well described by the philosopher of science
(slide 2) Karl Popper, who emphasised the importance of trial and error in science.

He argued that a scientist considers the data obtained by observations and experiments relevant to a natural phenomenon of interest, and then, through leaps of the imagination and intuition, develops a framework to consider that data, and generates a hypothesis to explain the phenomenon. This hypothesis is tested by using it to make new predictions, which are then examined by further experiments and observations. If the data do not support the hypothesis then it is either rejected, or modified and the new hypothesis tested by further observation and experiment. So science proceeds by trial and error with unsatisfactory hypotheses being rejected through a process of falsification. Popper goes further to argue that falsifiability is the principal way of distinguishing science from non-science. An important implication of this view of how science works, is that scientific knowledge evolves, and is often tentative especially at the beginning of an investigation. It is only after repeated testing that it becomes more secure.



Science is also influenced by the way scientists behave and interact with each other in a community. Scientists should be open, honest, rigorous in their thinking and sceptical, especially of their own ideas. An effective science community should be interactive and collaborative, and encourage the constant challenge of data, ideas and hypotheses. It is the overall strength of the evidence and argument that matter in science, not the hierarchical authority of the scientists involved.

The combination of these attributes and ways of working produces a methodology that underpins science and which is very effective at generating reliable knowledge of the natural world and ourselves.

So when did scientific thinking begin? When were the first reliable and reproducible observations made that allowed the recognition of regularities and patterns to be recognised and explanations generated? It is possible to detect such scientific processes in pre-history, good examples being the revolutionary changes which led to agriculture and metallurgy, and in the construction of astronomically oriented ritualistic structures such as Stonehenge. I will outline these and try to imagine the impulses which gave rise to them.


The agricultural revolution was dependent upon the domestication of wild plants, the selection and cultivation of crop plants with desirable characteristics. It first came about around 10,000 years ago in the fertile crescent of the Middle East with the cultivation of cereals, both wheat and barley, and later in the New World with maize. It required continuous cultivation and experimental trait selection to generate cereals with large grains and low seed dormancy that were convenient to harvest. This can be
seen with the development of the maize crop from the wild precursor plant
(slide 3) Teosinte.

I imagine that some observant hunter-gatherer must have noticed unusual rare plants with desirable characteristics growing amongst a mass of normal plants. Perhaps what that hunter-gatherer observed might have been
something like I observed this Spring, a white bluebell embedded in a mass of
(slide 4) blue bluebells.

The curiosity of such proto-scientists and their recognition of the potential usefulness of these unusual plants must have led to collection of their seeds and subsequent propagation of the derived plants. Over hundreds or probably thousands of years, subsequent proto-scientists would go on to select for even better combinations of characteristics until gradually the agricultural revolution was born. And this occurred not once but a number of times throughout the world with different crops. I find it difficult to imagine this happening unless these creative and innovative individuals were employing what we would now recognise as scientific approaches, using careful observation and recognising regularities and patterns within those observations. Given that this process happened independently a number of times over in different regions, the Middle East, the Far East, and the new World, it must have been very natural for at least some of our distant Homo sapiens forebears to think and to act like this.

Although later than the agriculture revolution, similar impulses must have generated the advances in metallurgy 5000-8000 years ago. A society dependent on stone, bone and wood, for its materials was in need of metal for
(slide 5) tools and implements and, inevitably, weapons.

Smelting required metal ore and high temperatures. Once again I imagine an observant individual, who must have noticed that heating a copper ore produced material that could be usefully fashioned to make tools and implements. Perhaps it was burning the charcoal produced from the day before in a camp-fire made on ground containing copper ore, that accidentally generated the temperature needed to produce copper. But once done and noticed, it was successfully repeated. Then 2000 years later, someone else may have smelted copper ore contaminated with tin to generate the more versatile bronze, starting another revolution in technology. Once again this is difficult to imagine without the individuals concerned observing carefully, and recognising regularities in behaviour of the natural world.

These advances were not always utilitarian in character. Our pre-history proto-scientists were also observing and studying the heavens above them, particularly the movement of the sun as the seasons changed. The regularities they observed were incorporated in great ritual structures aligned to important celestial events such as the longest day. The alignment of the heelstone with the stone circle of Stonehenge which corresponds to the
(slide 6) summer solstice is one of the best known examples.

Even more extraordinary is the tunnel above the entrance to the Newgrange Barrow in Ireland, through which light from the sun penetrates the depths of
(slide 7) the tomb around the winter solstice.

The precision of these alignments is evidence of the builders knowledge 4000-5000 years ago of the regular motions of the heavens, a knowledge built on reliable observation and recognition of reproducible patterns, the beginnings of science.

Although proto-science can be detected in pre-history, science is much more clearly articulated in the writings from classical Greece. The Ionian Period starting in Miletus around 600BC produced Thales, who provided explanations of the origins of the world derived from water, and Heraclitus, who argued that the world is dynamic, in constant flow. This is a picture of Miletus now in
(slide 8) Turkey, and of Thales.

Critically these early Greek scientists generated explanatory accounts which did not involve interventions from the Gods. They did not invoke divine creators as was the case for the earlier Sumerian, Egyptian and Babylonian creationist myths. Instead for example they proposed that the planets were globes of fire in the heavens, rather than Gods wandering in the sky. The important point here is not so much whether they were right or not, but that these thinkers were looking for explanations which were rational and did not derive from the supernatural. They were assuming that the world is explicable and can be understood by the rational workings of the human mind, a truly revolutionary step. However, not all in ancient Greece were happy with this rational approach. Socrates is reported to have been condemned by the political leadership in Athens to commit suicide by drinking hemlock, for
(slide 9) corrupting the Athenian youth with his denial of the existence of the Gods.

Two other features of science developed by the ancient Greeks, was the systematic description of nature, as pursued by the encyclopaedist Aristotle, and the carrying out of experiments as described by Strato the Physicist. The consequence was an explosion of ideas and scientific understanding, some of which remains important today, Aristotle provided the descriptive basis of biology and together with his followers founded his philosophical school the Lyceum, which can be considered the first scientific research institution. Democritus proposed a theoretical atomistic model for matter anticipating the atomic theories of Dalton and others two thousand years later. Aristarchus argued for a sun-centred heliocentric planetary system although this was not widely accepted until Copernicus, Galileo and others provided better astronomical observations of the planets to support this idea. Eratosthenes not only concluded the earth was spherical but also, by observing the lengths of shadows at noon, determined with quite extraordinary precision the
(slide 10) diameter of the earth.

Archimedes founded the science of mechanics until his work was tragically terminated by a Roman soldier at the siege Syracuse. The Romans do less well than the Greeks in the history of science.

The Greeks brought about a revolution in ideas that changed our world forever. They introduced the concept that the world was comprehensible, liberating humanity from the yoke of mysticism and superstition. They brought about long-lasting changes in our knowledge of the natural world. They started the development of mechanical technologies and of medicine for the benefit of humankind. It was a revolution that began the long journey to the Enlightenment which still continues today.

Realising that the workings of the natural world could be understood, meant that careful observation and meticulous experiment could be gathered together to provide knowledge of the world and insight into how that knowledge could be applied in useful ways to help society. In England at the turn of the seventeenth century, Francis Bacon, courtier, statesman and
(slide 11) philosopher was laying out his approach to science.

He emphasised the need for the gathering of reliable information, and then taking account of these particulars to formulate generalities, noting when occurrences of specific particulars were correlated with specific outcomes and when they were not. He famously argued for a sceptical approach in the pursuit of knowledge, saying

“If a man will begin with certainties he shall end in doubts, but if he will be content to begin with doubts, he shall end in certainties.”

He advocated that “knowledge is power” and that

“establishing a legitimate command over nature leads to the relief of man’s estate,”


in other words that science was useful. However it would have perhaps been best if he had confined himself to thinking about science rather than doing science. Driving during winter in Highgate London he stopped his carriage bought a hen and then stuffed it with snow to see if it would delay putrefaction of the bird. As a consequence of his outdoor experiment he caught a chill, developed bronchitis, and died several days later.

Meanwhile at the same time, but in the warmer climes of Italy, Galileo was more successful with his experiments and observations. His work studying the motions of balls descending inclined planes, established mechanics as science, and importantly he connected physics with mathematics, stating that the

“Book of nature is written in mathematical characters.”

But it was his acute practical observations combined with his rationalism, which led to the revolution that provided the evidence that moved the earth
(slide 12) from being the centre of the universe to a planet circling the sun.




Thus began a process whereby our terrestrial globe has become increasingly insignificant to just a speck in the universe. Our sun is a star, just one of billions in our galaxy, and our galaxy is just one amongst the billions that make up the universe. And maybe there are even countless universes. This revolution started when Galileo turned his simple telescope towards the planet Jupiter, and discovered the Medici stars circling the planet, named after his former pupil and subsequent employer the Duke of Tuscany. Clearly not all celestial objects were orbiting the earth, lending strong observational support to the heliocentric views of Copernicus. Eventually this led to his conflict with the Catholic Church who were concerned that the Copernican system could have worse consequences than both Luther and Calvin together. Galileo was forced to recant his ideas, possibly after encouragement by being shown the
(slide 13) instruments of torture.

Science does not always sit comfortably with religion, nor sometimes with those politics and ideologies that do not respect the primacy of evidence and rational argument.

This marked the first stirrings of the Enlightenment that Kant would eventually describe as the “emergence of man from his self-imposed infancy,” by which he meant that human-kind gained the resolve and the courage to use reason to understand the world, following the Roman poet Horace “dare to know”. That sentiment was central to the founding of the Royal Society in 1660, which ushered in the age of modern science. Its motto,

“nullius in verba” roughly translated as “take no-one’s word for it”,

reflects this emphasis on the need to rely on demonstrated observation and
(slide 14) experiment rather than established authority.

The early pinnacle of success for modern science, based on the application of mathematics to understand physics, was the work of Isaac Newton whose laws of motion led to the idea of universal gravitation. This provided a quantitative description of the motions of visible bodies, demonstrating that the motion of a small terrestrial object such as an apple falling from a tree was subject to the same laws that applied to the motion of large celestial objects like planets orbiting the sun. Although Newton’s laws did not provide a mechanism for gravity, the universality and scope of the law of gravitation and the predictive power and the precision of the calculations it allowed consolidated the revolutionary view, that the world could be understood by the use of reason, observation and experiment, even down to the very finest detail. Discoveries such as these also led to important applications. Robert Hooke, who also contributed to ideas about gravitation, but was expunged from history by the over-sensitive and priority seeking Newton, said:

“Scientific discoveries concerning motion, light, gravity, magnetism and the heavens, help to improve shipping, watches, optics and engines for trade and carriage.”

Once again science is revolutionary in character changing our view of the world and changing what we can do in the world. Knowledge of the movements of celestial bodies was central to navigation, which in turn was needed for journeys across the globe, another revolutionary step in the history of humankind.

Steven Shapin, the historian and sociologist of science, has emphasised another, perhaps less well recognised aspect of why the Royal Society so strongly influenced the birth of modern science. The Royal Society generated a way of working, which led to a scientific culture or sociology. Science was open to all professions, to those of different religions, to those of different races and classes. The weakness of the Royal Society, which was only corrected 300 years after its foundation, is that it did not include the participation of women, thus not profiting from half of the intellectual capital of humankind. However, for its time the Society was inclusive and tolerant, and international in outlook. It provided a community which promoted discussion, critical commentaries, advice and criticism. It invented the scientific journal, and the 350th anniversary of the first scientific journal, Philosophical Transactions will be celebrated next year, which incorporated the concept of criticism and reviewing from peers. The Society emphasised the importance of the public demonstration of experiments, the need to provide sufficient information for the work to be replicated elsewhere before it should be accepted. These sociological practices are crucial for the proper pursuit of science and remain important today.

Robert Boyle, a founding Fellow of the Society, argued that experiments should be reliable and reproducible, and to be properly witnessed by others. He also recommended public performance of experiments at the Society’s meetings and encouraged their description in sufficient detail that they could be replicated elsewhere. Thus the pursuit of the scientific endeavour embraced the communication of advances widely and publically, and the encouragement of debate. What emerged from this was the importance of consensus opinion amongst the scientific community. If an idea or a set of experiments and observations are found to be convincing by the majority of scientists familiar with the area, then they gain extra weight by having passed the test of scrutiny, often intense scrutiny from many experts. This is why the consensus opinion of scientific experts in an area is important, as it gives the most reliable overview available at that time of that area. It is not that consensus is a lazy agreement, quite the opposite in fact, the consensus will have been arrived at because it has stood the attacks and commentaries of other experts, who need to be convinced before they give their agreement and support for that view. That is how scientific consensus works today, so if an idea or hypothesis has value, it will generally spread rapidly through the scientific community and become the consensus view. And if it has limited or no value it will not do so, despite all the attempts of lobbyists to promote fallacious views in the lay public arena, as can happen in some scientific areas important for public policy. Climate science has suffered from these problems.

The Enlightenment and the Royal Society together with other scientific academies of the day, set modern science on its way. The consequence of this was knowledge that formed the technological basis for the Industrial Revolution that developed in the eighteenth and nineteenth centuries and continues today. The significance of the Industrial Revolution cannot be over-estimated, as it literally underpins the making of the modern world. The
(slide 15) technological advances were legion:

The development of new energy sources with steam, electric and internal combustion engines, and later nuclear and novel renewable sources of power; the use of new materials, iron and steel, ceramics, and later plastics; the invention of increasingly efficient machines of manufacture such as the power loom and spinning jenny leading eventually to the often robotised modern factory of today; the development of new means of transport, the rail locomotive, the steamship, the automobile, the aeroplane, onto the space ship; advances in communication and the management of information with the telegraph, the radio, the television, onto the computer and the world-wide web. But unfortunately, together with these advances for the good of humankind, there have also been the construction of increasingly more effective and deadly weapons of war. It is difficult to imagine any aspect of our present lives which is not influenced by these developments. They have brought revolutionary changes to everyone on the globe.

The Industrial Revolution was mostly based on the physical sciences, but the life sciences have contributed as well. Scientific approaches gradually increased agricultural production such that crop yields today for each acre of land under cultivation are many times higher today than in the early eighteenth century. If proper economic, social and distribution conditions were put in place, our improved scientific knowledge means that no-one should be hungry on the planet, a situation that was inconceivable in former times. The life sciences also brought about further new ideas and concepts which have led to revolutionary challenges to established opinion and orthodoxy, no more so
(slide 16) than in the idea of evolution.






Charles Darwin’s painstaking observations and meticulous arguments made the case for evolution. He argued that living organisms have evolved and are related by descent, and also postulated a major mechanism for evolution, that is natural selection. This demonstrated that the life sciences could be understood in terms of universal laws, just like the physical sciences, as Darwin himself recognised with the famous last sentence in the Origin of Species, referring back to Newton:
“whilst this planet has gone cycling on according to the fixed laws of gravity, form so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.”
But most importantly and still contentious for some today, Darwin’s ideas moved human beings from being specially created to being related to the rest of the living world. Just as Copernicus had moved the earth from being the centre of the universe so Darwin moved humankind from a unique position separate from the rest of life.
Charles Darwin was not the first to propose evolution. For example, his own grandfather Erasmus was a proponent of evolution, but Charles was the first to assemble the wealth of observation and experiment, combined with critical closely argued reasoning, which was necessary to convince his scientific colleagues and subsequently the world, of the validity of evolution. Science advances by good ideas but is completely dependent upon reliable and reproducible observation and experiment. It is from evidence that science draws its strength.
Another great advance of the nineteenth century which had revolutionary consequences was forged by John Dalton, a non-conformist teacher of
(slide 17) humble origins.

By the study of gases and the measurement of the relative weights of the elements, he gathered experimental evidence in favour of the existence of particulate atoms, increasing in mass by unitary increments. He proposed that atoms combined together in simple ratios to generate molecules. These experiments gave the first empirical support for the two thousand year old atomic speculations of non-divisible units proposed by Democritus as the ultimate structure of matter, once again illustrating that for scientific ideas to be accepted always requires evidence.
Dalton’s work illustrated another aspect of science: the strength of explaining a natural phenomenon in terms of the behaviour of components acting at simpler levels. Many scientific explanations are expressed in these reductionist terms. Some compare reductionism in an antagonistic way with holism, which emphasises the whole behaviour of the system responsible for the phenomenon under study. In my view this antagonism is misplaced because reductionistic explanations are extremely powerful, and in any case to be fully effective have to be placed in a holistic context. Reductionism and holism are not incompatible, they are mutually reinforcing. Dalton’s
(slide 18) achievements together with others such as the great chemist Lavoisier

laid the foundations of chemistry and of the chemical industry with revolutionary consequences for society through the development of new materials and chemical agents for practical purposes.

A second scientific advance of the nineteenth century built on the power of reductionism came from the plant breeding experiments of the Czech monk
(slide 19) Gregor Mendel.

His experiments led to a particulate explanation of heredity, that is inheritance is based on non-divisible units which we now call genes. This revolutionary advance spawned discovery after discovery in biology and biomedicine in the twentieth century. Genes were found to be made of DNA, the double helical structure of which gave rise to the idea that DNA acted as a digital information storage device and hence the whole edifice of molecular biology, which underpins much of modern medicine. Molecular biology is built on genetics and biochemistry, and on the view that the phenomena of life can be best understood in terms of information. Louis Pasteur laid the foundations for the biochemical mechanistic explanation of life with his studies of sugar beet fermentation by yeast, from which he concluded that

“chemical transformations are a physiological characteristic of life.”

(slide 20) Pasteur’s work undermined the concept of vitalism, by proposing that the functioning of living organisms could be understood in terms of physics and chemistry. This conceptual advance ushered in a new dawn of materialistic explanations of the phenomena of life, with great impacts on modern medicine and the pharmaceutical industry. The revolutionary influence of this advance has been extraordinary, leading to improvements in human health and increases in the longevity of humankind. Only one hundred years ago, even in developed countries such as the UK, life expectancy was around 50 years, probably only an increase of 15 years since the agricultural revolution 10,000 years previously. Yet in the last 100 years, life expectancy has increased to around 80 years. This change has its basis in science and is truly revolutionary, both for the well-being of individual human beings and for the whole demographic structure of society.

There has been another revolutionary consequence of modern biology for society centred on the questions of what it means to be human. If like other living organisms, human beings are to be understood in terms of their inherited genes and their chemistry, and their interactions with the environment, what does this mean for our sense of what we are, for free-will, for the use of punishment and justice, for equality and for racial, gender or other differences? These are profound questions for society. Studies based on evolutionary genetics and animal behaviour have implications for ethics and morality. Science has a habit of invading other domains of human activity where at first sight it appears to have no place. This was the case for Galileo and Darwin, and is still the case today, with modern scientific advances having increasing impacts on spheres of activity, once thought to be the domains solely of philosophy, of politics and of religion.

Modern physics has had another type of impact, also revolutionary, on the nature of human knowledge. Einstein in his theory of general relativity, proposed a continuum of space-time accounting for gravity, which undermined the common-sense view of the world expressed in terms of time and the three
(slide 21) dimensions of space.

Apart from brilliant reasoning, Einstein’s approach meant that the drive of science to predict and explain natural phenomena resulted in a theory that was no longer completely in accord with our common-sense, that is the Kantian view, that inherent to our framework of experience and understanding are time and the three dimensions of space. Twenty years after Einstein, studies of atomic structure led to Quantum Mechanics, an “Alice in Wonderland” world, a place where Schrödinger’s cats can be alive and dead at the same time. But despite not being explicable in terms of a common-sense understanding of the natural world, the subsequently developed Standard Model has led to extraordinary precision in predictability of the behaviours of the ultimate constituents of matter. This is a revolutionary shift in human knowledge, where explanations work beautifully, but are beyond our common-sense understanding. Where physics leads biology sometimes follows, and I wonder whether the complexity of living organisms will also lead to strange and non-intuitive explanations, which have predictive power but which are no longer part of our common-sense world.

It should also be noted that these physics studies led to nuclear power and the
(slide 22) nuclear bomb, which have had truly revolutionary impacts on society. Politics in the second half of the twentieth century were dominated by the Cold War and the threat of mutually assured mass destruction. The effects of this science on global politics have been huge.

I have argued that science is truly revolutionary, more so than revolutions
(slide 23) based on politics or ideology, or in the long-term, even religion.

This is because science leads to revolutionary advances in our knowledge of the natural world and ourselves, and because this scientific knowledge results in sustained revolutionary changes to human society and culture. What can we learn from the past that will help in the future to ensure that revolutions in scientific knowledge and understanding continue, resulting in revolutionary improvements in the human condition? The first of these questions is more straightforward. Great scientific advances are driven by great scientists. We need to provide scientific education and training to allow such scientists to develop, then we need to identify and support them with an environment and adequate resources so that they can prosper. Most importantly, they need to be given the freedom to pursue what they judge to be interesting and they should be protected from counter-productive interference from often well-meaning but sometimes misguided scientific managers and leaders. If we keep this in place then science will prosper.

More difficult is the second question, ensuring that science brings about revolutionary improvements in the human condition. This requires a good and healthy relationship between science and society. We need to ensure that science is used for the public good rather than the reverse. Science has always been employed for the purposes of war and such use can threaten our very existence. Over the millennia science has generated knowledge that has been used for the purposes of war and of oppression. Bronze led to both useful tools and to weapons, steam power led to both railways and to dreadnoughts, atomic physics both to nuclear energy and to the nuclear bomb. Ultimately making good decisions about the use of knowledge based on science depends on societies with the right values, underpinned by healthy effective democracies. For science to play its proper role, requires a public at ease with science, and a democracy that can cope with the complex decisions involving science.


There are threats to this. We need to be aware of those who mix up science, based on evidence and rationality, with politics and ideology, where opinion, rhetoric and tradition hold more sway. We need to be aware of political or ideological lobbyists who do not respect science, cherry picking data or argument, to support their pre-determined positions. We need to aware of those who distort science to support particular fundamentalist religious beliefs, not based on the rigour of rational argument and data, but on faith and revelation. We need to be aware of the relativists who argue that knowledge is culturally determined such that all views are acceptable, even those not supported by reliable evidence and rational reasoning. Revolutions are unsettling and are often strenuously opposed. This has been the case with Copernicus moving the earth from the centre of the universe, and with Darwin who argued that man was not specially created. No doubt there were some who rejected the agricultural revolution of Neolithic times, just like some who reject the possible advantages of GM crops today, even when they can be for the public good.

At its best society has shown it can deal with these threats, I am optimistic that in the future society will increasingly see the value of science in bringing about revolutionary changes to our knowledge, and revolutionary improvements in society and the human condition. Science is truly the most long-lasting revolutionary activity known to humankind, and will continue to bring great benefits to us all.