The Strange and Wonderful World of Self-Interest

“Virtues are lost in self-interest as rivers are lost in the sea” 

— François de La Rochefoucauld

Self-Interest Is Not Static

Many people misunderstand self-interest. Too often, it is treated as a synonym for selfishness. In reality, selfishness is only one expression of self-interest, which is much broader and inclusive of all our intentions. Self-interest is better understood as a portfolio of who we are—a mix of motives, roles, and trade-offs that shift across time and situations. Some expressions lean selfish, others lean selfless, and most lie somewhere in between. Just as important, our perception of another person’s self-interest is filtered through our own. This constant interaction of motives and perceptions is what underpins the invisible hand and the workings of market economics.

This is why self-interest exists on a continuum. At one end lies the purely selfish—actions elevating one’s own short-term gain at others’ expense. At the other lies pure selflessness—sacrifices made for others without regard for personal cost. Most of us, most of the time, occupy the messy middle.

What makes self-interest fascinating is its inconsistency. Nobel laureate Daniel Kahneman, often called the father of behavioral economics, described this as a “failure of invariance”—our tendency to make different choices when logically identical situations are framed in different ways. We can be deeply selfless in one situation and unmistakably selfish in another. Even stranger, two people may each separately watch the same third person in different situations. Later, when they compare notes, one may describe the person as selfish and the other as selfless. It can sound as if they are talking about two completely different individuals—yet both accounts accurately reflect the very same person. Their after-the-fact discussion is revealing not only of the third person’s differing self-interests across situations, but also of how their own self-interests shape their judgments.

Self-interest is dynamic, ever-changing, and context-dependent. It reflects the trade-offs we face across time horizons, social roles, and emotional states. The Scottish Enlightenment—through thinkers such as David Hume, Adam Smith, Francis Hutcheson, and Adam Ferguson—was pivotal in reframing this dynamism. What earlier traditions, including the church, often cast self-interest as a flaw to be restrained, they recognized it as the essence of human behavior. This insight not only helped inform the founding of America but also became essential to the rise of the market era. By designing legal frameworks and institutions that could channel diverse self-interests, the Scottish Enlightenment unlocked extraordinary innovation, cooperation, and human flourishing.

Why the Inconsistency Makes Sense

Thinkers from across disciplines—Adam Smith in economics and moral philosophy, Richard Dawkins in biology—remind us self-interest is not just about individual gain. It is about balancing short- and long-term incentives, weaving in obligations to family, community, and even genetic survival. What seems inconsistent on the surface is often consistent when framed across broader situations and time horizons.

In other words: today’s selfish impulse may support tomorrow’s selfless outcome. The continuum of self-interest is not linear—it bends and loops, shaped by time, role, and context.

Four Everyday Examples of Dynamic Self-Interest

Self-interest is not only about what we want for ourselves, but also about how we want to be perceived by others. As Adam Smith reminded us, “Man naturally desires, not only to be loved, but to be lovely.” This dual aspiration—seeking recognition while trying to live up to it—explains why everyday situations reveal such different shades of self-interest.

1. The Parent at Work and at Home A parent may stay late at the office to secure a promotion. To co-workers, this can appear selfish: prioritizing career over family. Yet at home, the same parent might sacrifice personal hobbies and sleep to help with homework or attend a recital. In one role, the parent appears self-focused; in another, selfless. The truth is both. Career advancement funds the family’s well-being, while caregiving secures long-term relational and emotional returns.

2. The Student on a Saturday Night Imagine a college student choosing between studying for an exam and going out with friends. If they hit the books, their peers may call them selfish for skipping group time. If they go out, a professor may see irresponsibility. From the student’s perspective, either choice could be rational depending on priorities: career goals, friendships, stress relief, or future earnings. Self-interest here is not fixed—it flexes with context and who is doing the judging.

3. The Volunteer and the Social Media Post Someone who spends Saturday mornings volunteering at a food pantry might seem selfless. Yet when they post about it on Instagram, some may dismiss it as virtue signaling—a selfish attempt to earn likes or status. In reality, both motives can coexist: the act delivers real community benefit while also enhancing reputation, showing how layered self-interest often is. Both views miss the bigger picture: volunteering delivers community benefits and reputational benefits simultaneously. What looks like inconsistency is actually layered self-interest—short-term recognition intertwined with long-term service.

4. The Friend Who Both Shares and Withholds Consider a friend who listens patiently when others need to vent, but avoids sharing their own struggles. To some, this seems selfless generosity. To others, it seems selfish secrecy—denying others the chance to reciprocate. Yet both behaviors can stem from the same root: a desire to preserve harmony in the relationship. Self-interest, in this case, toggles between giving and withholding, guided by context and personal calculation.
   

The Nuance: Relative vs. Absolute Perceptions

“Our preferences are not stable—they vary with the framing of outcomes. This is the failure of invariance.” 

— Daniel Kahneman

From experience, it does seem some people live further to the “selfish” side of the spectrum and others lean more toward the “selfless.” Genetic predispositions, upbringing, job demands, wealth, or cultural background can create lasting tendencies in one direction. But here lies the challenge: much of what we perceive is relative and situationally dependent.

I may see someone as selfish because of how they interact with me, while another person, in a different context, may find the same individual remarkably selfless. When we later compare notes, our absolute judgment about where this person “sits” on the continuum is shaped not only by their behavior, but also by our own self-interests and priorities. Knowing where someone truly sits is difficult because observation is never neutral—we only ever see a slice of their behavior, filtered through our own perspective. This relates to a quantum mechanics principle: physicists discovered you cannot measure both a particle’s position and its momentum at the same time—the act of observing one obscures the other. In the same way, observing someone else’s self-interest makes it challenging to see how our own self-interest shapes the judgment. Without knowing the full range of situations across relationships—and without factoring in our own perspective—it is nearly impossible to make a definitive judgment.

Thus, it is usually safest—and healthiest—to withhold judgment and focus on experiencing the best in the people around us. We cannot fully know how others experience the same person and how our own self-interests impact the perception, but we can choose to interpret their actions generously, recognizing self-interest is never fixed.

The Economic Power of Diverse Self-Interests

The inconsistency of self-interest is not just a human quirk—it is the raw material of prosperity. David Ricardo’s principle of comparative advantage shows how people, firms, and nations create more value by specializing in what they do relatively best and then trading with others. What looks like uneven abilities becomes a system of complementary strengths.

Add Wright’s Law, which shows costs fall predictably with each doubling of production experience, and the story grows even more powerful. Markets, fueled by billions of shifting self-interests, generate learning curves accelerating innovation, reduce costs, and make life-improving goods widely available.

The results from the market era speak for themselves. Over the past two+ centuries, the diversity of human self-interests—channeled through trade, specialization, and innovation—has helped double global life expectancy and expand GDP by orders of magnitude. Extreme poverty, once the norm for most of humanity, has plummeted to historic lows.

This is the paradoxical beauty of self-interest at scale and harnessed by markets: while individual choices may seem inconsistent, in aggregate they form the foundation for cooperation, progress, and flourishing. The same diversity of self-interests sparking judgment is also what fuels extraordinary community growth when it is allowed to interact freely.

The Takeaway: Embrace the Paradox

“When we stop judging, the world reveals itself as it is—fluid, changing, and interconnected.” 

— Buddhist teaching on impermanence (anicca)

The point is not to label people as selfish or selfless. The point is recognizing self-interest is a portfolio, not a fixed personality trait. It is an evolving mix of motives, incentives, constraints, and trade-offs shifting with time, circumstance, and perception.

Rather than condemning inconsistency, we should see it as a feature of human adaptability. It is what allows us to balance personal needs with collective obligations, to make trade-offs between today and tomorrow, and to navigate the attention-saturated environment of modern life.

Closing Thought

Self-interest is strange because it can make us look like different people depending on 1) who is obeserving and 2) when and how we are observed. But it is wonderful because it reflects the complexity of being human. By acknowledging its dynamism—and remembering the relativity of our judgments—we can move beyond simplistic labels, design better decision frameworks, and ultimately thrive in an era where attention, not information, is the scarce resource.

To explore the research foundations of this perspective, see the articles:

• “Making Self-Interest Work: How to Thrive When Attention Is Scarce and Choices Are Infinite”

• "The Power of Practice and Specialization: Why Market Economics Expands Human Potential"

• "Adam Smith and how choice architecture makes the invisible hand more visible"

• Physics metaphor: The core metaphor is the Heisenberg Uncertainty Principle: in quantum mechanics, you cannot know both a particle’s exact position and momentum at the same time; the act of measuring one obscures the other.

  Thus, observing others’ self-interest is like measuring position; reflecting on how our own self-interest shapes perception is like momentum. We rarely grasp both at once — and our observation itself changes what we can “see.”