We live in societies that are more diverse and more polarised than ever before. Across cultures, religions, and political beliefs, people are confronted daily with views and values that differ profoundly from their own. How should individuals navigate that reality? According to Lester Chen, PhD candidate at Erasmus School of Law, the answer lies in a concept that is as old as philosophy itself: tolerance. But Chen approaches it in a way that is anything but conventional. He argues that tolerance should be understood not merely as a political principle, but as an individual virtue that each of us can develop and practise in daily life.
On 18 June 2026, Chen defends his dissertation: ''Tolerance: A Moral Virtue'' under the supervision of Wibren van der Burg, Professor emeritus of Theory and Methodology at Erasmus School of Law and Machteld Geuskens, Assistant Professor of Legal Theory and Legal History at VU Amsterdam.
Tolerance as virtue, not just policy
The central question of Chen's dissertation is deceptively simple: should we understand tolerance as an individual virtue? His answer is yes. Drawing on Aristotle's virtue ethics, he argues that tolerance meets all the criteria of a genuine virtue: it can be developed through practice, it requires practical wisdom, and it contributes to human flourishing. "Tolerance is not an innate trait," Chen explains, "but a virtue that can be developed through practice, just like other virtues."
This framing sets his work apart from much of the existing literature, which tends to treat tolerance primarily as a political or legal principle; something for lawmakers and institutions to uphold. In philosophical and legal discourse, tolerance is often reduced to a binary choice: either prohibit something or allow it, as if not banning a practice were automatically the same as tolerating it. Chen does not dismiss that dimension but insists it is incomplete. A government or institution that truly possesses the virtue of tolerance, he argues, would focus on the deliberative process behind such decisions: Have we communicated sufficiently with diverse groups? Have we attempted to view the world from their perspective? Tolerance, in other words, must also be a personal virtue, a continuous process of self-reflection and understanding, not merely a final decision.
Chen also expands the definition of tolerance itself. In philosophical discourse, tolerance typically refers to objecting to a cultural practice or belief on moral grounds, yet refraining from interfering with people's freedom to act accordingly. Chen argues that the threshold can be lower than that. Even if our discomfort with a different group stems from personal preference rather than moral objection, ‘’we are still practicing tolerance as long as we restrain the impulse to interfere and allow others to maintain their way of life.’’
Take the example of women wearing burkinis at public pools. Whether someone objects on cultural grounds, has a different view on women's rights, or simply dislikes the aesthetic, as long as they do not interfere with others' freedom to wear it, they can be considered tolerant. This means that being tolerant does not require saintly acceptance. It simply requires restraint and a willingness to allow others to live differently.
How can people learn to be more tolerant?
The term 'tolerance' is widely used but rarely examined with precision. One of the dissertation's distinctive contributions is a cross-framework comparison. Chen analyses how Kantian deontology, utilitarianism, and virtue ethics each handle moral diversity, and argues that virtue ethics offers the best framework for understanding tolerance. But he does not stop at theory. He also dives into a very practical question: how can people actually learn to be more tolerant?
To explore this, he draws on the Enneagram, a psychological model as a heuristic that identifies nine personality types and describes how each tends to see the world and interact with others. By combining philosophy and psychology, Chen examines how people with different characters might develop tolerance as a genuine habit, through deeper self-understanding and genuine empathy. It is an approach that is rare in the existing literature.
We can strive to be individuals who tolerate differences
The societal relevance of Chen's research extends well beyond academic philosophy. The question of how individuals can genuinely engage with each other despite differences, rather than suppressing or ignoring them, is urgent.
Chen is careful to avoid naive idealism. He acknowledges that deep dialogue is not always possible: "We may not always have the energy and time for deep dialogue. However, we should at least strive to uphold our own values while leaving flexibility and space for others." His advice to readers is practical: start small. "Before deciding whether to ban women from wearing burkinis in public waters, we should first put ourselves in their shoes and ask if there are legitimate reasons why they wish to do so. To become more tolerant, we can start by being willing to endure the slight discomfort that comes with shifting our perspective."
Tolerance, in his framework, is a realistic and learnable starting point, a foundational moral practice from which greater understanding and compassion can grow. "While it may be difficult to express love and acceptance toward those who are fundamentally different from us," he explains, "at the very least, we can strive to be individuals who tolerate differences."
The measure of success
For Chen, the success of his research is measured not in citations, but in conduct. Every individual who chooses to embrace difference, rather than turn away from it, represents the kind of impact he hopes his work will have.
Chen is open about the fact that believing in his own ideas took time and encouragement. What surprised him most was the freedom his supervisors gave him. "They made me realise that I am indeed capable of joining the conversation among philosophers and contributing my own original ideas," he reflects. Equally important was a shift in perspective: learning that the goal of a dissertation is not to convince everyone, but to continuously refine one's thinking until it is cogent and defensible. That insight, he says, significantly eased the pressure and allowed him to gradually build genuine academic confidence.
He is candid about the difficulty of the process itself. "It is not easy to maintain passion and motivation during long periods of repetitive, deep-thinking writing." But he is equally warm about the support he found at Erasmus School of Law. The School, he says, did more than teach theory: "They offered practical guidance and helped me build mental resilience." His advice to those just starting out is simple: "Please cherish the School's curriculum and your supervisors' guidance, and use these opportunities to cultivate your own resilience and competence."
- PhD student
