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Science Is Not Another Opinion

clean face and bearded face on front and back of a bust

Credit: Svetlana Pasechnaya

Is science just another opinion? As the weeks unfold into months in the COVID-19 pandemic, scientists have struggled to understand the disease, how best to treat it, and how to find a vaccine. The frustration over new outbreaks and the difficulties of containing the disease have embroiled mainstream politics. Some politicians, claiming their policies are science-based, handpick scientists whose expert opinions align with their political views. Scientists appear on talk-show panels where their expert opinions are treated like the political opinions—with admiration if they agree with yours, disdain if they do not.

Treating science as if it is just another opinion is a disservice to science and to humanity. As computing professionals, we rely on science to support our work and give confidence that our systems can be trusted. What makes science different from political, journalistic, barroom, or dinner-table opinions?

Scientists investigate the natural and social worlds to understand how things work and learn their laws of operation. Many scientific laws begin as professional opinions, or hypotheses, that evolve into statements that are so well supported by evidence that no one doubts them. When this happens, the statements are called "settled science." The profession of science has adopted a "scientific method"—a standard way of formulating and proving or disproving scientific hypotheses. Science is open to the possibility that new evidence may disrupt settled science. In other words, science is never sure it has discovered "truth." To look at science as a method of finding truth is hubris. The issue is not who has the "truth," but whose claims deserve more credence.

Let us investigate why that scientists doing their best work on new questions may disagree. The disagreements hasten the journey to settling the scientific questions.

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Science and Public Policy

When making important decisions governments around the world usually seek the advice of the best scientists available to apply relevant theory and data to draw conclusions on the likely outcomes of policies. Scientists, the media and the general public usually approve and applaud this commitment to "evidence-based policy." Science is seen as stronger than the multitude of opinions from ideologies and dogmas. In this spirit governments around the world initially took a science-based approach to the coronavirus pandemic of 2020 and frequently said, "Our policy follows the science."

This arrangement endured for some time, especially in the early days when nobody really understood what was going on as the number of infected people soared exponentially and hospitals filled up alarmingly with sick and dying people. In the face of this existential crisis most people wanted to pull together and stand behind their governments.

Scientists in many countries built models to predict the spread of the disease and evaluate which possible interventions were most likely to contain it. In the U.K., the government turned to its Scientific Advisory Group of Experts (SAGE), which is made up of some of the most eminent and respected scientists in the country. Relying on models developed by Neil Ferguson of London's prestigious Imperial College, SAGE advised that severely restricting citizen movement and contact was the most effective means to "flatten the curve" and keep hospitals from being overwhelmed. The U.K. government introduced a severe lockdown on March 23, 2020 that caused the most massive social and economic shock in 70 years. Many other countries followed suit and a worldwide economic depression quickly followed.

As these draconian measures were introduced dissenting voices began to be heard from citizens groups, economists, the wider scientific community, and even from within SAGE. It became common to hear scientists disagreeing with each other on the radio and TV. Now "following the science" lost its certainty as the politicians, media, and public realized that there was no single clear and authoritative scientific account. The media depicted the scientific community as a squabbling rabble. In the eyes of some science became discredited and it became obvious that government policy was being driven by political ideologies that overrode the science.

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Had Science Failed?

Definitely not. Worldwide science has performed magnificently during the pandemic. In January 2020, we knew almost nothing about COVID-19. Its spread was declared to be a pandemic by the World Health Organization three months later. Scientists have accumulated and synthesized a huge amount of knowledge in a very short period, much of which is not contested. With the help of massive political support, science and industry found three effective vaccines for COVID-19 in a record time of less than a year. Science is working and doing what it is supposed to do. To understand the achievements and contribution of science to the existential threat of COVID-1 it is necessary to understand the scientific process and the contingent nature of scientific knowledge.

Disagreement between scientists is a normal, healthy part of the scientific process.

In his 1934 book Logik der Forschung (The Logic of Scientific Discovery), Karl Popper established the principle of falsifiability as the main criterion distinguishing science from non-science. Falsifiability means a scientific claim is open to being shown wrong. Newton's laws (1687) were unchallenged for the next 200 years because no one found any contrary evidence until the Michelson-Morley experiment in 1887. Then in 1905 Albert Einstein's theory of relativity falsified Newton's laws for objects moving close to the speed of light. Einstein's theory inspired great skepticism. The skepticism broke in 1919 when Arthur Eddington's solar eclipse experiment exactly confirmed the bending of light passing near the sun, an important prediction of Einstein's theory.2 Then, some of Einstein's theory was overthrown by quantum mechanics in the mid-1920s. Popper claimed that other theories such as Marx's economics and Freud's psychoanalysis cannot be empirically falsified and are not science.

The falsifiability principle is not as definitive as Popper made it out to be. Scientists frequently argue over whether apparently contradictory evidence is strong enough to be taken as falsification. The social sciences, rejected by Popper as sciences, by and large accept the need for evidence and for rigorous statistical testing of their hypotheses about human behavior. Statistical testing has limitations. The usual "95% confidence" means that one in 20 conclusions may not be supported by the evidence. Similarly, the statistical methods of medical sciences in double-blind clinical testing allow a small number of trials to fail as long as the vast majority support the claims.

Disagreement between scientists is a normal, healthy part of the scientific process. When something completely new like COVID-19 appears scientists will explain the early observations with a variety of theories and explanations. The scientific process culls out the theories that can be refuted and moves to a consensus on the ones strongly supported by evidence. Even among those that fit the existing observations some can be falsified by new observations. All these early theories are scientific, even though they may contradict each other. The worldwide search for a vaccine was scientific even though its outcome was uncertain because everyone was prepared to abandon a candidate vaccine if the evidence showed it did not work.

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The Dual Nature of Science

There is a paradox in science that you might not have much thought about. On the one hand, the historical accounts of settled science are familiar, reasoned, and methodical. On the other hand, the actual work of investigating and verifying hypotheses is fraught and often chaotic. How can science be methodical and chaotic at the same time? How does science resolve chaos into order?

This paradox has serious implications during times when science is searching for answers that have yet to be found, as in the COVID crisis. To outsiders, it may seem the chaos indicates that the scientific process has collapsed and is not working, and that the claims of scientists cannot be trusted. In fact, the chaos is an integral part of the workings of science and dealing with it is necessary to achieve settled science.

Bruno Latour addresses this paradox in his book Science in Action.1 He makes a fundamental distinction between "ready-made-science" and "science-in-the-making." Ready-made science, also called settled science, is the models, theories, and laws that are now taken for granted and are ready for use to build systems and make predictions about nature and the heavens. Science-in-the-making is quite unsettled because scientists do not yet know if a hypothesis is verifiable or how to go about verifying it. It is infused with uncertainties, controversies, dead ends, and fierce debates among scientists. It is highly emotional, passionate, and unsettling. Latour illustrates his point with a detailed analysis of the hypothesis that DNA is a double helix. Today that statement is taken for granted and is the basis of gene sequencing, genetic engineering, DNA analysis, CRISPR gene editing, and more. But the process of coming to this conclusion was fraught with disputes among the leading scientists, emotional name-calling, misfired claims of first discovery, and supreme disappointments about being upstaged. Latour grounds this with extensive quotes from the writings of the scientists involved at the time.

Latour depicts this dual nature of science with an image the two-faced Roman God, Janus. One face, seasoned and creased with lines of wisdom, looks back over all that has happened and tells us what is true and repeatable. The other face, youthful and brash, looks forward and tries to make sense of the unknown ahead. These opposing faces embody inverted interpretations of the world. Latour illustrates with contrasting aphorisms such as in the table here.

Table. Contrasting aphorisms (from Latour1).

How does a hypothesis move from uncertainty to settled science? Favorable evidence increases confidence in the hypothesis. Unfavorable evidence decreases it. The processes of science—such as publication, exchanges at professional meetings, debates, round-tables, extensive experimentation and testing—all contribute to removing doubt about the original hypothesis. When all the doubt has been removed and there are no remaining dissenters, the scientific community accepts the hypothesis as a fact. Latour says that the process of scientific settlement is one of hypotheses accumulating allies until there are no more dissenters. It is intensely social.

Different communities can and do evolve different statements of scientific facts based on the same evidence.

Some people do not like the notion that scientific interpretations are social inventions. They think that scientists are teasing out fundamental, immutable truths about the world. Social construction allows the possibility that different communities could adopt different systems of interpretation of the same phenomena. And exactly that has happened. Western and Chinese medicine are different systems for interpreting and treating symptoms of diseases. Biology includes a community that accepts the theory of evolution and another that accepts the theory of intelligent design by a higher being. Strong and weak artificial intelligence are different systems for interpreting machine implementations of cognitive processes. Within computing there are different communities around different programming languages or software development processes. These communities and their interpretations are durable—when a community tries to present falsifying evidence to the other side, the other side instead finds a way to interpret that evidence as supportive of its interpretation.

A scientific interpretation must be accepted by a scientific community to be considered settled. Scientific facts are interpretations accepted by a whole scientific community with no dissenters. Different communities can and do evolve different statements of scientific facts based on the same evidence.

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Working Science Pierces the Fog of Uncertainty

These two faces are integral parts of science. Science has a dual nature. We all need to be aware of it and respect it. The chaos of science-in-the-making will evolve either into settled hypotheses or rejected hypotheses.

When outsiders look in at a time of chaos, they will see hypotheses floating around but no general agreement. It will seem that scientists don't agree—and that is exactly right. However, the disagreements do not mean that science is not working. The debates and controversies are essential to settle or reject hypotheses.

The front edge of science—the boundary region between the known and the unknown—seethes with uncertainties. Scientists must be prepared not only to apply wisely what is known, but also to find their way through the fog of uncertainty as they search for what can be known.

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1. Latour, B. Science in Action: How to Follow Scientists and Engineers through Society. Harvard University Press, 1987.

2. The Times Newspaper. Revolution in science: New theory of the universe: Newtonian ideas overthrown;

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Peter J. Denning ( is Distinguished Professor of Computer Science and Director of the Cebrowski Institute for information innovation at the Naval Postgraduate School in Monterey, CA, is Editor of ACM Ubiquity, and is a past president of ACM. The author's views expressed here are not necessarily those of his employer or the U.S. federal government.

Jeffrey Johnson ( is Professor of Complexity Science and Design at the UK Open University. He is Vice President of the UNESCO UniTwin Complex Systems Digital Campus, an Associate Editor of ACM Ubiquity, and past president of the Complex Systems Society.

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