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Sources of Knowledge
Challenging the Objectivity of Science
Sina Mirzaye Shirkoohi observes science to get the facts straight about it.
In his influential 1976 textbook What Is This Thing Called Science?, Alan Chalmers examines how scientific knowledge is acquired and validated, by looking at the methods underpinning scientific inquiry. He presents and explores the idea that science is fundamentally grounded in the acquisition of objective knowledge through direct observation; that sensory data serves as the bedrock upon which scientific understanding is built. Then he describes some of the criticisms of this picture, and various attempts by recent thinkers to build a more accurate model of the development of science. I want to carry this is a little further. The central thesis of my critique is that observations in science are not purely objective: they’re influenced most notably by theoretical frameworks, prior knowledge, and subjective biases that shape how data are perceived and interpreted.
The Traditional View of Science
The traditional view is that science is grounded in observable facts obtained through direct sensory experience. These observations are objective: facts that are indisputable, checkable, independent of the foibles of the individual observer and directly accessible through our senses. This unparalleled level of objectivity, it is widely believed, distinguishes science from other forms of knowledge, making it a beacon of certainty in a world filled with personal biases and unfounded opinions. It shows that the scientific method is an unswerving path to truth, free from the messiness of individual perspectives.
As Chalmers notes, this conception is appealing because it promises a reliable and unambiguous understanding of the natural world. However, he begins to unravel this simplistic portrayal by delving deeper into the nature of observation. If all scientific inquiry is based on what we can observe, then it’s crucial to examine the reliability and objectivity of these observations. He introduces the concept that observations may be theory-laden – and if so, that this may undermine their function as a neutral foundation for science. When we observe a phenomenon, how can we be sure that what we’re perceiving is objective reality rather than an interpretation influenced by our own prior knowledge and theoretical commitments?
The idea of ‘theory-ladenness’ suggests that what scientists observe is significantly shaped by the theoretical frameworks they hold. Indeed, philosopher of science Norwood Russell Hanson famously argued that “there is more to seeing than meets the eyeball” (Patterns of Discovery, 1958, p.6), implying that observation is an active process, involving interpretation. Chalmers himself emphasizes that observations are not made in a theoretical vacuum, and that our sensory experiences are filtered through cognitive lenses shaped by our existing theories and beliefs. This means that two scientists observing the same phenomenon may interpret it differently based on their theoretical backgrounds.
In The Structure of Scientific Revolutions (1962), Thomas Kuhn expands on the idea of ‘theory-ladenness’ by introducing the concept of paradigms – frameworks of thinking that guide scientific research, such as the paradigm of evolution, or of quantum mechanics, or of Newtonian mechanics. These paradigms include not only the theories, but also the methods, standards, and values shared by the scientific community using them. According to Kuhn, normal science operates within such paradigms, and observations are interpreted to fit with the theoretical structure of the paradigm. After decades or even centuries, the weight of anomalies and overcomplicated interpretations within a paradigm may trigger a shift to a new paradigm – what he calls a scientific revolution. After that, normal science resumes within the new paradigm and the pattern repeats.
Some might argue that science employs methods to minimize subjective biases, such as standardized measurements, controlled experiments, and peer review processes. These practices aim to ensure that observations are reliable and replicable, reinforcing objectivity. Yet while these methods enhance the rigor of scientific inquiry, they can only partially eliminate the influence of existing theories on observation. As Paul Feyerabend contends in Against Method (1975), methodological rules are themselves influenced by theoretical perspectives, and a strong adherence to strict methodologies may hinder scientific progress by suppressing alternative viewpoints.
The realization that observations are theory-laden has profound implications for science. It challenges the traditional view that science is purely objective and calls for a more nuanced understanding of how knowledge is constructed. Scientific inquiry becomes not merely a straightforward collection of facts, but a dynamic process involving interpretation and reinterpretation within theoretical frameworks.
Illustration © Jaime Raposo 2025. To see more of his art, please visit jaimeraposo.com
Case Study: Galileo’s Observations
An example that highlights the theory-ladenness of observation is Galileo’s use of the telescope to observe the moons of Jupiter. Galileo’s interpretation was influenced by his support for Copernican heliocentrism – the idea of a Sun-centred solar system (The Sidereal Messenger, 1610). Critics of Galileo, adhering to the traditional Earth-centred model, either dismissed his observations or interpreted them differently. This shows how theoretical commitments can influence not only data interpretation, but also the acceptance of empirical evidence. Galileo’s ability to interpret his observations was profoundly influenced by his prior acceptance of the Copernican model, of the planets all revolving around the Sun. He did not merely record visual data through his telescope; he interpreted what he saw. Chalmers emphasizes that Galileo’s observations were not neutral facts awaiting discovery but were imbued with theoretical significance. Without the heliocentric theory as a framework, the movement of Jupiter’s moons might have been dismissed or interpreted differently. That some of Galileo’s contemporaries, such as Christoph Clavius, were skeptical of his observations, illustrates very well how theoretical commitments shape perception. Their refusal to accept the existence of Jupiter’s moons was not due to a failure in observation, but a consequence of the observation conflicting with their entrenched geocentric worldview.
This example underscores the idea that observations in science are not free from theoretical influence. It’s crucial to understand that human perception is inherently active. First, our brains do not passively receive sensory data, but actively organize and interpret it based on prior knowledge and expectations. Cognitive psychology also indicates that perception is a process of integrating new information with existing cognitive structures. One might argue that Galileo’s use of empirical evidence effectively challenged and eventually overturned the dominant geocentric paradigm, demonstrating the power of observation. However, this would overlook the initial resistance his findings faced due to prevailing theoretical biases. It was not merely the observations themselves but the gradual shift in theoretical acceptance, that led to the heliocentric model’s eventual dominance.
Extending the discussion generally, when a researcher peers through a microscope or looks at any data from scientific equipment, what they see is profoundly influenced by their training, theoretical background, and expectations. For instance, in the early twentieth century, the interpretation of atomic spectra was deeply connected to the developing theory of quantum mechanics. Without that theoretical framework, the spectral lines observed would have remained unexplained.
All these examples challenge the notion that scientific facts are simply waiting to be discovered through observation. Instead, they demonstrate that understanding in science arises from a complex interplay between empirical data and theoretical interpretation. Recognizing this interplay is crucial because it acknowledges the human elements in scientific inquiry, which include creativity, intuition, and subjectivity. And as Feyerabend provocatively argued, adherence to strict methodological rules can sometimes hinder scientific progress by suppressing creative and unconventional approaches.
A Critique of Empiricism & Positivism
Empiricism – the view that knowledge primarily stems from sensory experience – has an illustrious history. The influential early empiricists John Locke (1632-1704) and David Hume (1711-76) argued that the human mind begins as a tabula rasa – a blank slate – and that all knowledge is acquired through sensory input. This perspective maintains that all understanding arises from direct interaction with the world. What we can see, touch, hear, and measure forms the foundation of all credible knowledge. The simplicity of this idea is appealing, as it suggests a straightforward path to truth by relying on observable, tangible evidence. In the early twentieth century, logical positivists such as A.J. Ayer expanded upon empiricist principles by claiming that only empirically or logically verifiable statements are even meaningful. They aimed to eliminate metaphysics and focus strictly on propositions that could be tested either through direct observation or logical analysis. This movement reinforced the belief that scientific knowledge is built upon objective facts derived from sensory experience.
However, the empiricist and positivist emphases on sensory data as the sole source of knowledge has been critiqued for oversimplifying the complexity of perception. One significant challenge here is the recognition that our sense organs are not merely passive receptors of external stimuli, but that their responses to stimuli are actively interpreted by the brain. And as we’ve seen, prior knowledge, expectations, and theoretical frameworks influence what we perceive as facts. This means that sensory data are not objective, but are shaped by our cognitive structures. This active role of cognitive interpretation in knowledge acquisition challenges the views of both empiricism and positivism. Moreover, in The Structure of Scientific Revolutions Kuhn argues that the paradigms that science operates within define ‘legitimate’ scientific problems and their solutions: observations are interpreted to reinforce the prevailing paradigm, and anomalies may be ignored or dismissed until a paradigm shift occurs that can incorporate them. This idea of scientific progress challenges the logical positivist view that science progresses by accumulating objective facts. Psychological research also supports the claim that perception is an active process. For instance, studies in cognitive psychology demonstrate that what individuals perceive is affected by schemas developed from prior experiences. This suggests that even at the level of primary perception, our minds filter and interpret sensory data.
Again, proponents of empiricism might assert that scientific methodologies are designed to mitigate subjective biases. Techniques such as controlled experimentation, standardized measurement, and peer review enhance objectivity; and experiment replication, and precise instruments are designed to enhance the reliability of observations. However, while these practices undoubtedly do strengthen the scientific process, they can only partially eliminate the influence of theoretical frameworks upon observation.
Another argument by ‘pure’ empiricists might be that science’s predictive success lends credence to the idea of the objectivity of the empirical method. Scientific theories based on empirical data have indeed led to huge technological advancements and astoundingly accurate predictions about natural phenomena. However, as WVO Quine discussed in ‘Two Dogmas of Empiricism’ (Philosophical Review, 60:1, 1951), the underdetermination of theory by data implies that multiple theories can be consistent with the same set of observations. This implies that theory choice involves criteria beyond empirical observation alone – such as simplicity, coherence, and explanatory power.
These critiques suggest that acquiring scientific knowledge involves a complex interplay between sensory data and cognitive interpretation. Recognizing this complexity doesn’t devalue empirical evidence, but does call for a more nuanced appreciation of how scientific knowledge is constructed.
The Fallibility of Observation Statements
A prevalent misconception is that observations, by virtue of being directly accessible through the senses, provide indisputable facts about the world. However, Chalmers argues that observations are not infallible truths; they are provisional, and subject to revision. They are tentative brushstrokes on the expansive canvas of scientific knowledge, influenced by the observer’s biases, limitations, and the current state of theoretical understanding. He uses the metaphor of trying to read a street sign through foggy glasses to illustrate how our perceptions are affected by our cognitive lenses. Just as foggy glasses obscure vision, preconceived notions and theoretical commitments can distort our interpretation of sensory data. This aligns with Hanson, who argued that all observations are theory-laden and that what we see is influenced by what we expect to see.
Understanding the fallibility of observation statements is crucial because it further challenges the notion that scientific facts are simply waiting to be discovered through observation. Instead, it emphasizes that what we perceive as ‘facts’ are often interpretations shaped by our understanding at the time. More generally, as W.A. Sandoval notes (in ‘Understanding Students’ Practical Epistemologies and their Influence on Learning Through Inquiry’, Science Education, 89:4, 2005), learners’ practical beliefs about knowledge and knowing influence how they interpret and engage with scientific evidence.
So it’s essential to recognize that science is not a static endeavor of collecting immutable external facts. Instead, it is a dynamic, ever-evolving process characterized by continuous questioning, probing, and revising. Making progress involves both the accumulation of observations, and the constant scrutiny and reinterpretation of those observations in the light of new evidence and theories. A good historical illustration of this process is the shift from Newtonian physics to Einsteinian relativity. In Newtonian mechanics, concepts such as absolute space and time were considered empirical truths, supported by the observations and experiments of the era. However, Einstein introduced a new interpretive framework that redefined space and time, and demonstrated that measurements of both are relative to the observer’s frame of reference. A new empirical observation did play a role in this paradigm shift: the 1887 Michelson-Morley experiment's unexpected finding that there was no significant difference between the speeds of light in two orthogonal directions despite the movement of the Earth through space. However, this would have remained a puzzling anomaly without Einstein's daring theoretical reconceptualisation of the notions of space and time. Again, observations are interpreted within theoretical frameworks, and as those frameworks change, so does our understanding of the observations. This highlights the iterative nature of science, where today’s accepted truths may become tomorrow’s outdated concepts.
A counterargument to the idea of the provisional nature of scientific knowledge is that the convergence of independent observations leads to reliable knowledge over time. But although it is true that repeated observations can strengthen confidence in specific ideas, the history of science shows that widely-accepted interpretations can still be overturned. The phlogiston theory of combustion, once a dominant explanation supported by observations, was eventually replaced by the oxygen theory of combustion after Lavoisier’s experiments. This shift occurred not merely due to new observations, but because of a new theoretical framework that provided a better explanation of the phenomena, in turn leading to better experiments.
Conclusion
This critique highlights that the notion of science being purely derived from objective observable facts is an oversimplification. While observations are undeniably crucial to scientific inquiry, they are intricately intertwined with theory, interpretation, and scientists’ personal perspectives. Recognizing that observations are theory-laden underscores that science is not merely about collecting empirical data, but involves a dynamic process of interpreting and re-evaluating findings within theoretical frameworks.
This has profound implications for the philosophy of science. It challenges the traditional view of science as an entirely objective endeavor based solely on sensory data, by emphasizing the essential role of theoretical constructs and human cognition in shaping scientific knowledge. This invites a more nuanced understanding of scientific objectivity, which acknowledges the complex interplay between empirical evidence and theoretical interpretation. Exploring how this interplay influences scientific progress across various scientific disciplines would be valuable for future reflection, and could provide insight into the evolution of scientific knowledge. Such exploration can deepen our appreciation of the intricate processes that drive scientific discovery, and encourage ongoing dialogue about the nature of objectivity and subjectivity in science.
© Sina Mirzaye Shirkoohi 2025
Sina Mirzaye Shirkoohi is a PhD Candidate at the Faculty of Administrative Sciences of the Université Laval in Québec City.