The nature and limits of science
Every approach to understanding the world has limits
Science is one of humanity's most powerful tools, continually advancing our knowledge, technology, and capabilities. It has enabled us to explore everything from the subatomic to the cosmic scale, cure diseases, reach the moon, extend lifespans, and develop computers. Yet, like any approach to understanding the world, science has its limits.
What is science?
Science is a way of thinking that explores the physical world through a specific approach, with a defined purpose and focus. It relies on sensory observation, empirical testing, and human reasoning, following a structured process known as the scientific method.
The scientific method involves systematic observation, measurement, and experimentation to develop theories and models. While the steps can be presented in varying forms, a common example of the scientific method includes the following steps:
Purpose/Question – What do you want to learn? Which are faster, cats or dogs? Does the color of the light make indoor flowers grow faster?
Research – Read books, search online, and talk with experts about the topic. You do this to help you formulate your hypothesis.
Hypothesis – After researching, make a testable prediction (hypothesis) of the answer to the problem. An example is “Orange light will make plants grow faster than using blue or red light.”
Experiment – Design and experiment to test your hypothesis.
Analyze– Record your results (the data) and analyze it to see how they answer your hypothesis.
Conclusion – You may find that your hypothesis was correct, but you may find it was wrong and come up with a new hypothesis(es) to test. Write and report your conclusion.
Science is rarely straightforward. Research and experiments often yield unexpected results, leading to new hypotheses and further testing. Many discoveries arise from accidents, serendipity, or sudden insights, and scientific inquiry often branches into new areas. Creativity plays a central role in this process.
As ongoing research and new findings emerge, models and theories are frequently revised or replaced. Science is an ever-evolving pursuit. Unlike superstition and pseudoscience, which offer simple, often untestable answers that avoid critical examination, science demands rigorous testing and evidence.
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Falsification and Provisional Knowledge
Science works on the principles and reality of falsificationism and provisional knowledge.
Falsificationism posits that we cannot definitively prove something to be true, only that it can be proven false. For a hypothesis to be scientific, it must be testable. When repeated testing fails to disprove the hypothesis, it is considered provisionally true, meaning it is accepted as correct for the time being, but subject to change if future evidence contradicts it. This is often referred to as a working theory. Consequently, all scientific knowledge, theories, and models are provisional.
For example, consider the universal statement "All swans are white."
Even if all observed swans by scientists, birdwatchers, and others have been white, it is still impossible to claim with certainty that all swans are white, as not every swan has been observed, and a non-white swan could exist or have existed. However, based on current observations, "All swans are white" can be considered provisionally true.
Humans, including scientists, can never be 100% certain about anything, and scientific results are expressed in probabilities. Scientists continually test and refine their models and theories as new information emerges.
One of the inherent limits of science is that it cannot attain absolute certainty. Paradoxically, one of its greatest strengths is its acknowledgment of this uncertainty.
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Areas Beyond Science
Science is limited by its strict focus on what can be observed and tested, using human logic and empirical methods. There are, however, realms that fall outside of what science can address. The following are some examples of areas that lie beyond scientific investigation and logic.
Art
Art, in terms of personal and sublime experiences and meaning, cannot be "proven" or objectively analyzed through science. While science can measure elements like the frequency of a musical note or the colors in a painting, it cannot determine what qualifies as art, what makes art good or bad, or what an artwork signifies.
Morals and Ethics
Science and logic cannot determine what is morally right or wrong, ethical or unethical. There are no scientific methods to decide whether acts such as murder, rape, or theft are morally acceptable, nor can science evaluate the relative importance of humans compared to other animals or assess the merits of political systems like democracy versus dictatorship.
There is no objective scientific test to establish what makes a law good or bad or what is the best way to structure society. Morality and ethics are shaped by culture, philosophy, and personal belief rather than by empirical evidence.
Spirituality, Mysticism, and the Existence of God
The existence of God or any higher power cannot be scientifically tested, as these concepts lie outside the natural world that science investigates. God is often described as supernatural, existing beyond the scope of human senses and reasoning, and therefore beyond the reach of scientific inquiry.
Scientists, like everyone else, have personal beliefs about spirituality and religion. For instance, my academic peer reviewers—one a medical scientist at Oxford University and the other an applied mathematician at the British National Foundation for Educational Research—hold different views: one is an atheist, and the other is Catholic. While they may agree on scientific matters, their opinions on topics outside the realm of science diverge.
Meaning, Purpose, and Metaphysical Truth
Science cannot answer questions about the meaning or metaphysical truth of the universe, the purpose of human life, or whether such things even exist objectively. While scientists may have personal opinions on these matters, those opinions are not scientifically grounded. Many of our views on life’s big questions involve non-scientific and non-logical thinking.
The Value and Worth of Science
There is no scientific test to determine whether science is the best or correct method for understanding reality, or whether it is better, worse, or equal to other ways of knowing, such as religion, spirituality, or art. Science is neutral on these subjects and cannot objectively compare itself to them. Claiming that science is the best way to understand the world is an opinion.
Science and religion, or rationality and art, address different questions and have different scopes. Charles Townes, a Nobel laureate in physics and a devout Christian, noted, said that science explores the physical nature of the universe, while religion deals with questions of meaning.
How Science Is Applied
Science itself cannot tell us how to use its discoveries. Applied sciences—such as engineering or pharmaceutical development—rely on subjective decisions about how to apply scientific knowledge and what products or technologies should be created. These choices often involve ethical and societal considerations outside the realm of pure science.
Scientific Concepts Beyond Testing
Some scientific phenomena are so rare, and some theories require such extensive observation, that they cannot be tested as thoroughly as science demands. Universal scientific laws—believed to apply everywhere and for all time—cannot be fully tested because we cannot observe everything for all time. Concepts involving infinity, eternity, or "always" cannot be empirically tested.
Additionally, there are scientific theories—such as those regarding time, alternate universes, or the origins of the cosmos—that are widely accepted or considered plausible, yet scientists acknowledge that they may never be testable through scientific methods.
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Science's Axioms
Science is built on a foundation of unprovable assumptions, referred to as axioms. Some of these axioms are beliefs that may seem obvious and universally accepted, while others are simply definitions or rules necessary to make scientific systems function. Here are a few key assumptions in science:
Naturalism
Naturalism is the philosophy that only natural laws and forces operate in the world, excluding supernatural or spiritual explanations. While this idea is fundamental to scientific inquiry, it remains unprovable.
Objective Reality Exists and Can Be Studied
Science assumes that there is an objective physical reality outside of human perception that can be studied and understood. However, humans are limited by their senses. Even if we trust our perceptions, we know they are not always reliable. Our senses are prone to limitations and distortions, and we can never fully know the extent of these inaccuracies. This raises the question: Can anything be perceived objectively? Is objectivity itself a human construct?
The Reliability of Human Logic and Reason
Science relies on logic and reason as trustworthy tools, but this assumption is unprovable. Logic itself is built on axioms. Even if logic is reliable, its application is limited in scope.
Mathematical logic, for example, uses unproven axioms that are accepted because they seem self-evident to humans. However, all human systems, including science and logic, require assumptions and definitions to function.
The issue with axioms is that changing them can lead to drastically different outcomes. Since axioms are unproven and arbitrary, why not replace some of them? What if science altered its assumption of naturalism or the reliability of human logic?
Existential Truth
Science cannot definitively prove existential truths. For example, it cannot show that you weren't born five minutes ago with implanted memories, or that the universe isn't a computer simulation run by a mad scientist or alien. While these ideas may seem outlandish, humans are probably blind to crucial information about the universe and themselves. Some of our fundamental assumptions about reality may be flawed or incomplete.
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Scientific Models and Theories as Functional Tools, Not Representations of Reality
Scientific models and theories are tools designed to predict and explain physical phenomena but are not whole or necessarily accurate representations of reality.
A scientific model or theory provides a simplified view of a specific subject, crafted for a particular purpose. It is edited, simplified, and shaped by scientist to make it useful and understandable. In this way, models are partly about the subject they represent and partly about the humans using them.
Consider a paper map of the world. It is a helpful tool, but it's full of distortions compared to the actual Earth. For one, the world isn’t flat, yet we flatten it onto a map for convenience. Colors, borders, and roads are exaggerated or added for clarity. Even though these distortions are not true to life, they make the map useful for navigation.
Scientific theories and models function similarly: they are practical but do not perfectly mirror reality.
The concept of instrumentalism in science emphasizes the practical use of models and theories, focusing on their ability to predict outcomes rather than their representation of reality. This is a useful way to understand scientific models.
In some cases, models that are known to be inaccurate are still used because they work well in certain contexts. For example, physicists continue to use parts of Newton’s laws and some of Einstein's theories, even though more accurate models exist, because these older models are still effective for predicting certain phenomena.
Sometimes, multiple, seemingly contradictory models are necessary to explain the same phenomenon. A prime example is the wave-particle duality of light. Light behaves like a wave and a particle, even though these behaviors appear mutually exclusive. This duality demonstrates that nature doesn’t always conform to human logic and intuition.
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Summary
Science is an essential tool for understanding the physical world. Like all human endeavors, it is limited by uncertainty, biases, and scope. While science has its imperfections, it remains a powerful method for exploring and predicting natural phenomena.
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