We often frame societal risks in terms of immediate, visible threats: pandemics, climate disasters, or geopolitical conflicts. Yet one of humanity’s most persistent dangers—economic inequality—rarely occupies the same urgency in public discourse.
David Lay Williams’ compelling book, The Greatest of All Plagues: How Economic Inequality Shaped Political Thought from Plato to Marx, challenges this oversight by excavating an important truth: for over two millennia, the West’s greatest minds have sounded alarms about concentrated wealth’s corrosive effects on societies.
From Plato’s warning that inequality creates “two cities — one of the rich, one of the poor, eternally at war” to Adam Smith’s fear that vast income gaps erode mutual sympathy between classes, history’s sharpest thinkers have identified economic disparity as an existential threat to justice, democracy, and human flourishing.
At this event, David Lay Williams and an expert panel discussed what we can learn from the past about the threat of economic inequality, why philosophers considered it so disruptive and destabilising, and how we can make this threat more tangible to provoke action.
Speakers
- David Lay Williams, Professor of Political Science at DePaul University and Affiliate at the University of Chicago's Stone Center for Research on Wealth Inequality and Mobility
- Karen Rowlingson, Dean of the Faculty of Social Sciences and Professor of Social Policy at the University of York
- Luke Kemp, Research Affiliate at the Centre for the Study of Existential Risk, Cambridge
- Will Snell, Chief Executive at the Fairness Foundation (chair)
Event summary
David Lay Williams | Professor of Political Science at DePaul University and Affiliate at the University of Chicago's Stone Center for Research on Wealth Inequality and Mobility
David opened the discussion by outlining the central thesis of his book, The Greatest of All Plagues: How Economic Inequality Shaped Political Thought from Plato to Marx. David emphasised that concerns about inequality are not new. From Plato to Marx, Western philosophers have repeatedly warned that concentrated wealth is not just a problem of poverty or deprivation, but a root cause of social and political instability.
Plato, for example, argued that extreme disparities between rich and poor create “two cities” within one, sowing the seeds for civil war - the “greatest of all plagues.” This theme recurs throughout history: Adam Smith worried that inequality erodes sympathy between classes, while Rousseau and Marx saw it as a source of domination and class conflict. David contended that these thinkers, despite differing first principles, agreed that broad economic inequality undermines justice, democracy, and human flourishing.
A key point is that inequality’s dangers go far beyond the obvious harms of poverty. David organised these harms into four categories: personal, moral, social, and political.
- Personal harms: Inequality injures the poor not only through deprivation but by undermining dignity and self-worth. Thinkers like Hobbes and Rousseau described how poverty in unequal societies becomes stigmatised as a personal failing, compounding psychological harm. Less intuitively, inequality also damages the rich, who become afflicted by pleonexia - an insatiable greed that leaves them perpetually dissatisfied.
- Moral harms: Concentrated wealth, according to Plato and others, corrupts character. The rich, driven by the lust for more, become intemperate, unjust, and lacking in empathy or wisdom.
- Social harms: Inequality breeds division and animosity between classes. Adam Smith observed that the rich lose the ability to empathise with the poor, while John Stuart Mill spoke of “concealed enmity” between social groups. Marx saw class antagonism as an inevitable outcome of capitalism.
- Political harms: Perhaps most importantly, inequality undermines democracy. The wealthy capture political power, shaping laws and policies to serve their interests-a process described by Mill as “class legislation” and by Plato as oligarchy. Historically, this dynamic often leads to civil unrest or even collapse.
David also challenged the modern doctrine of “sufficientarianism” - the idea that only poverty matters, not inequality. He argued that this view ignores the broader harms of concentrated wealth, as recognised by the very philosophers often cited by sufficientarians.
Karen Rowlingson | Dean of the Faculty of Social Sciences and Professor of Social Policy at the University of York
Karen connected these historical insights to contemporary evidence. She cited influential research, such as The Spirit Level by Wilkinson and Pickett, which shows that societies with higher inequality suffer from worse health, more violence, lower social trust, and greater environmental harm. She also referenced Ingrid Robeyns’ concept of “limitarianism”- the idea that there should be limits on excessive wealth to protect democracy and social cohesion.
Karen emphasised the self-reinforcing cycle between economic and political power. Wealthy elites use their resources to influence policy, reduce taxes, and shape public discourse - often through media ownership - thus perpetuating inequality. This cycle, she argued, explains why, despite overwhelming evidence of harm, little progress has been made in tackling wealth concentration, particularly in the UK.
She also highlighted how narratives of meritocracy - promoted by those with power - justify inequality by framing the wealthy as deserving and the poor as responsible for their plight. However, public attitudes are more nuanced, and there is significant support for taxing wealth.
Karen pointed to the importance of structural factors, including the historical roots of wealth in violence, colonialism, and exploitation - issues explored by Marx and contemporary scholars. She also stressed the need to recognise the racial and gendered dimensions of wealth inequality.
Luke Kemp | Research Affiliate at the Centre for the Study of Existential Risk, Cambridge
Luke reinforced the panel’s warnings by drawing on historical and empirical research linking inequality to societal collapse. He cited studies by Jack Goldstone, Peter Turchin, and others showing that rising inequality consistently precedes political instability, coups, and even the fall of civilisations. When wealth is concentrated at the top, more people compete for elite status, and frustrated elite aspirants are able to whip up public anger about poverty and inequality, often leading to conflict and eventually to societal breakdown.
Luke argued that inequality not only weakens societies internally but also makes them less resilient to external shocks, such as climate change or pandemics. The top 1% are disproportionately responsible for carbon emissions, and inequality drives both environmental destruction and the risks posed by new technologies.
He also challenged the myth of meritocracy, noting that most young billionaires inherit their wealth, and that power and privilege tend to erode empathy and virtue - findings supported by neuroscience and psychology.
Discussion and Q&A
The panel discussed a range of solutions to inequality, both historical and modern. Williams noted that thinkers from Plato to Marx advocated for radical redistribution, whether through limits on property, debt ‘jubilees’, or redistribution. The biblical Jubilee laws - in which all land and property was to be restored to its original owners, every 50 years - and Plato’s ideal of limiting the wealth gap to a 4:1 ratio were cited as examples of historical proposals.
Karen and Luke advocated for progressive taxation, including wealth taxes, and policies to prevent the wealthy from capturing political power. Luke also suggested that deliberative democracy approaches would help to make decisions less susceptible to elite influence.
All agreed that tackling inequality requires both policy change and a shift in public attitudes, challenging the narratives that justify wealth concentration.
The discussion ended with a sober assessment of the challenges ahead. David noted that periods of greater equality in history - such as after World War II - were often achieved only after catastrophe, citing Walter Scheidel. However, he expressed hope that societies can learn from the past and act before reaching crisis point.
The panelists concluded that economic inequality is not just a moral or economic issue, but a fundamental threat to democracy, social cohesion, and even civilisation itself. Addressing it requires both bold policy and a renewed commitment to fairness.