Knowing the Unknown: Metaphor and Science in Aristotle, Kant and Hanson

For centuries, a quiet tension has existed between the language of science and the language of poetry. Science is expected to be precise, literal, and unambiguous, describing the world exactly as it is without the flourish of images or comparisons. Metaphor, by contrast, has often been dismissed as a decorative tool for writers or a simple teaching aid, something to be discarded once the hard facts are established. This view suggests that to speak scientifically is to speak without metaphors. However, a new analysis challenges this long-held assumption, proposing that metaphor is not merely a way to dress up known facts, but a fundamental engine for discovering the unknown. When scientists encounter phenomena that their current tools and concepts cannot explain, they do not simply stop; they turn to metaphor to build new ways of seeing. This process is not about inventing fiction, but about finding a bridge between what is already understood and what remains a mystery, allowing the mind to organize new experiences and spot patterns that were previously invisible.

The paper, titled "Knowing the Unknown: Metaphor and Science in Aristotle, Kant and Hanson," brings together three thinkers from vastly different eras to demonstrate that this reliance on metaphor is a universal feature of scientific discovery. The authors, Gonzalo Martin, Martin Heredero, and Alfredo Marcos, do not simply list historical examples; they construct a systematic argument showing how metaphor functions as a necessary cognitive tool whenever literal knowledge hits a wall. They examine the work of Immanuel Kant, the eighteenth-century philosopher who questioned the limits of human understanding; Norwood Russell Hanson, a twentieth-century philosopher of science who studied how scientists actually observe the world; and Aristotle, the ancient Greek philosopher who first analyzed how language shapes thought. Despite their different backgrounds, all three converge on the same conclusion: metaphor is not external to scientific rationality but is one of the conditions that make scientific discovery possible.

The argument begins with Kant, who recognized that human understanding has strict boundaries. Our minds are naturally wired to explain things through cause and effect, like a machine where one part pushes another. However, when we look at living organisms, this mechanical view often fails. A plant or an animal does not behave like a clock or a gear system; its parts exist for the sake of the whole, and they create one another in a way that a machine cannot. Kant argued that when our standard concepts run out, we must use a special kind of mental image, which he called a "symbolic presentation." This is not a literal description, but a way of thinking about a living thing as if it were the product of a wise designer, even if we cannot prove such a designer exists. This metaphorical thinking does not deceive us; rather, it allows scientists to continue their inquiry into life's complexity when a purely mechanical explanation is impossible. It acts as a guide, letting the researcher navigate the stormy ocean of the unknown without crashing into the limits of their own concepts.

The paper then moves to Hanson, who shifted the focus from how we think to how we see. Hanson argued that there is no such thing as a "pure" observation where a scientist simply records what their eyes see without any prior knowledge. Instead, what we see is always "theory-laden," meaning our existing beliefs and concepts shape our vision. To illustrate this, the authors discuss the famous case of Galileo and Thomas Harriot, who both looked at the Moon through a telescope in the early seventeenth century. They saw the same light and dark patches, but they did not see the same thing. Galileo, trained as an artist, recognized the patterns of light and shadow as topographical relief, seeing mountains and valleys. Harriot, lacking that specific framework, saw only a flat, mottled surface. It was only after Harriot saw Galileo's drawings, which used the language of art to describe the Moon, that he could "see" the mountains himself. This shows that metaphor and analogy are not just words added after the fact; they are the very frameworks that allow us to organize our visual experience and discover new entities. Without the metaphorical leap to see the Moon as a landscape, the mountains would have remained invisible.

Finally, the authors return to Aristotle to uncover the deep cognitive mechanism behind these insights. For Aristotle, metaphor was not a rhetorical flourish but a powerful tool for learning. He defined it as the ability to recognize a similarity between two things that are otherwise very different. When a scientist uses a metaphor, they are not just making a comparison; they are performing an act of discovery, spotting a real, objective connection that allows them to transfer knowledge from a familiar area to an unfamiliar one. The paper notes that while Aristotle insisted on precise, literal definitions for the final proofs of science, his own biological writings were full of metaphors and comparisons. This was not a contradiction but a necessity. When the strict rules of demonstration could not yet explain a new phenomenon, metaphor was the only way to catch a glimpse of the truth. It allowed the scientist to see the shape of the unknown before they could define it with exact terms.

The synthesis of these three perspectives reveals a powerful truth about how science advances. The authors argue that the opposition between scientific language and metaphorical language is a false one. Metaphor does not mark the limit of rationality; it is the very tool that allows rationality to expand. When established concepts cease to be sufficient to understand reality, metaphorical thought opens new avenues of inquiry. It enables scientists to reorganize their experience, to see familiar objects in new ways, and to find the hidden similarities that lead to discovery. Whether it is thinking of a living cell as a self-organizing system, seeing the Moon as a landscape, or recognizing a pattern in a dream, the act of knowing the unknown relies on the ability to imagine a connection where none was previously visible. In this view, the scientist is not a passive recorder of facts but an active explorer who uses metaphor to build the bridges that lead from the known to the unknown.