The concept of “common sense” holds a paradoxical status in human thought. On the surface, it suggests a form of shared understanding, practical judgment, or inherent knowledge that all reasonable people, regardless of their backgrounds, should possess. In casual discourse, we often invoke it as something self-evident, a kind of moral or practical compass that guides behaviour in everyday situations. “Use your common sense” is a phrase uttered when something seems so obvious it should not need explaining. Yet, when we examine the notion more closely, we find that “common sense” is far from a simple, universal category. In fact, it may be argued that common sense, as a concept, cannot truly exist at all. This is because human experience, knowledge, culture, and perception are inherently varied, and what seems like common sense in one context or to one person may be utterly foreign or irrational to another.
One key to understanding why common sense cannot exist is the realisation that human knowledge and perception are fundamentally subjective. We do not live in a neutral, shared reality, but rather in a world that we interpret through the lens of our individual experiences, beliefs, and cognitive biases. Philosophers have long discussed the nature of subjective versus objective knowledge. The 18th-century Scottish philosopher David Hume argued that much of what we take as “common sense” is based on habit and custom rather than reason or empirical evidence. In Hume’s view, humans are creatures of habit, and our minds naturally form associations between events based on experience, even when there is no rational or necessary connection between them. These associations become so deeply ingrained in our thinking that we mistake them for universal truths. Thus, what seems like “common sense” to us may be nothing more than a product of our own limited perspective, conditioned by repeated experience, but with no universal or rational foundation.
For instance, consider the assumption that objects fall downwards when dropped. This seems like common sense because it is something we observe constantly in our everyday lives. Yet, without the scientific framework of Newtonian physics or Einstein’s theory of general relativity, this “common sense” observation lacks explanation or deeper understanding. A person from a pre-scientific society might have attributed this phenomenon to the will of gods or unseen spirits, which to them would seem just as obvious and self-evident as the concept of gravity does to us today. Similarly, notions of “up” and “down” might not hold the same significance in a different culture or context. A person living in space, for example, would not regard gravity or the direction of falling objects in the same way. What appears as common sense from one perspective is therefore contingent upon a specific set of experiences, and cannot be presumed to be universally applicable.
Moreover, the very idea of “common sense” is deeply tied to cultural norms, and these norms vary dramatically across different societies and historical periods. The ancient Greeks believed in the idea of a natural hierarchy, where some people were naturally suited to rule while others were destined to be ruled. To them, this was common sense—a fundamental truth about the world. However, in contemporary democratic societies, such a belief is widely rejected. To suggest that some people are inherently superior to others by virtue of their birth or social standing is not only seen as lacking in common sense but as fundamentally unjust. This shift reveals that what is considered “obvious” or “natural” is often a reflection of the prevailing values and power structures of a particular society, rather than an objective truth. As values and power structures change, so too does what counts as common sense.
The fluidity of what we regard as common sense can also be observed in the realm of social etiquette and customs. In some cultures, it is considered impolite to refuse food or drink when offered by a host. In others, declining such offers is a mark of respect, showing that one does not wish to impose on the host’s generosity. Both of these practices may be framed as matters of common sense within their respective cultures, yet they are in direct contradiction with one another. Similarly, the concept of personal space varies significantly from one culture to another. In some societies, standing close to others during conversation is seen as a sign of engagement and friendliness, while in others it is considered intrusive and uncomfortable. Here again, what seems like common sense to one person may strike another as bizarre or inappropriate.
One might object to these examples by suggesting that while cultural norms and customs vary, there must still be some basic, shared form of common sense that transcends these differences—perhaps something grounded in human nature itself. However, even this assumption is problematic. Human nature, if it exists in any fixed or essential form, is not easily defined, and philosophers have long debated what, if anything, can be said to be universal about the human experience. The French philosopher Michel Foucault famously argued that human nature is not a stable or permanent feature of reality, but is instead constructed through the systems of power and knowledge that govern societies at different times. For Foucault, what we take to be natural or self-evident is always shaped by historical and cultural forces, and thus there can be no universal or timeless “common sense.”
Even basic cognitive processes, which we might assume to be shared by all human beings, are shaped by cultural factors. The way we perceive and interpret the world is influenced by the language we speak, the education we receive, and the social contexts in which we live. The Sapir-Whorf hypothesis, a well-known theory in linguistics, suggests that the structure of a language can influence its speakers’ perception of reality. For example, languages that have no future tense may lead their speakers to think about time in fundamentally different ways than those who speak languages that do make a distinction between past, present, and future. If something as basic as our perception of time can be shaped by language, then it stands to reason that what we consider to be “common sense” might also be influenced by such cultural and linguistic factors.
A striking example of this can be found in the concept of “time” itself. Western societies tend to conceptualise time as linear, with a clear distinction between past, present, and future, and a focus on progress and forward movement. This view of time may seem like common sense to many people living in industrialised nations. However, in other cultures, time is understood in a more cyclical or fluid manner. Many Indigenous cultures, for example, view time as a series of repeating cycles, with the past, present, and future all interconnected rather than distinct. In these societies, the idea of linear progress may seem nonsensical or irrelevant. Once again, what appears as common sense in one context may be utterly foreign in another.
The variability of common sense is not only a matter of cultural difference but also of individual variation. Cognitive biases, personal experiences, and emotional states all play a role in shaping what we perceive as self-evident or obvious. For example, the “confirmation bias” is a well-documented phenomenon in which people tend to seek out information that confirms their existing beliefs and ignore or dismiss information that contradicts them. This bias can lead individuals to believe that their own perspective is the only rational or sensible one, even when it is based on flawed or incomplete information. In such cases, what seems like common sense to one person may be regarded as irrational or misguided by another.
Furthermore, the influence of emotion on judgment cannot be underestimated. Psychological studies have shown that people are more likely to rely on intuition or “gut feelings” when they are under stress or experiencing strong emotions. These intuitive judgments may feel like common sense in the moment, but they are often shaped by emotional responses rather than rational deliberation. For example, a person who is afraid of flying might insist that it is common sense to avoid air travel, even though statistical evidence shows that flying is far safer than driving. In this case, the person’s emotional response to the idea of flying overrides the objective facts, leading to a perception of common sense that is not grounded in reason.
Another philosophical perspective that challenges the existence of common sense comes from the tradition of existentialism. Thinkers such as Jean-Paul Sartre and Martin Heidegger emphasised the idea that human beings are radically free and that there is no pre-existing essence or set of guidelines that can dictate how we should live our lives. For Sartre, the idea of “common sense” is an illusion because it assumes that there is a given, objective way to live that applies to all people. In reality, Sartre argues, we are condemned to create our own values and make our own choices in a world that offers no clear or universal answers. Common sense, in this view, is a comforting fiction that allows us to avoid confronting the existential responsibility of defining our own path.
Heidegger similarly argued that human beings are “thrown” into the world, meaning that we are born into a specific cultural and historical context that shapes our understanding of reality. However, this understanding is always partial and incomplete, and we are constantly confronted with the possibility of seeing things in a different way. For Heidegger, the idea of common sense is problematic because it assumes a stable, unchanging world in which things have a fixed meaning. In contrast, Heidegger’s philosophy suggests that meaning is always in flux, and what seems like common sense at one moment may be revealed as arbitrary or contingent at another.
Even within the realm of science, which is often seen as the domain of objective truth, the concept of common sense is fraught with difficulty. Scientific discoveries frequently challenge what was once considered to be common sense. For centuries, it was common sense to believe that the sun revolved around the earth. This geocentric model of the universe was widely accepted because it fit with people’s everyday experience of seeing the sun move across the sky. It took the work of Copernicus, Galileo, and others to challenge this view and demonstrate that the earth actually revolves around the sun. Similarly, the theory of evolution by natural selection, proposed by Charles Darwin, overturned the common-sense belief that species are fixed and unchanging. In these cases, what was once considered common sense was shown to be based on a limited understanding of the natural world
Therefore, the concept of common sense cannot exist in any meaningful or universal way because human knowledge, perception, and experience are fundamentally diverse and contingent. What seems like common sense to one person may be completely alien or irrational to another, depending on their cultural background, individual experiences, and cognitive biases. Philosophers from Hume to Foucault have challenged the idea that there is any universal, self-evident knowledge that applies to all people in all contexts. Even in science, where objective truth is often sought, the history of discovery shows that common sense is frequently overturned by new evidence. As human beings, we are constantly interpreting and reinterpreting the world around us, and what seems obvious today may be questioned or rejected tomorrow. Therefore, common sense, far from being a reliable guide to reality, is little more than a reflection of our own limited and subjective perspectives.
