The phrase you are thinking of is "Homo homini lupus"—"Man is a wolf to man."

While it is most famously associated with the 17th-century English philosopher Thomas Hobbes, he actually wasn't the first to say it. The line originates from the Roman playwright Plautus in his 254 BC play Asinaria. Hobbes revived it in his work De Cive (1642) to describe the terrifying, lawless state of nature before the creation of a centralized state.

Whether it's actually true is one of the foundational debates of political philosophy and evolutionary biology. Here is how that debate breaks down:

The Hobbesian View: Absolute Competitive Scarcity

Hobbes argued that without a strong, governing authority (the "Leviathan") to keep everyone in check, humans would inevitably descend into a perpetual war of all against all.

• The Core Argument: Resources are scarce, and because humans are generally equal in their ability to harm one another, fear and self-preservation drive us to strike first. In this state, life is famously "solitary, poor, nasty, brutish, and short."

• The Implication: Human nature is fundamentally egoistic, and "morality" or "justice" can only exist once an overarching power is established to enforce laws.

The Counter-Argument: Mutual Aid and Co-evolution

Many thinkers and biologists argue that the "wolf" metaphor misunderstands both humans and wolves.

• The Biological Reality: Actual wolves are fiercely cooperative pack animals that rely on deep social bonds, shared hunting duties, and altruism to survive. They rarely kill members of their own pack.

• Philosophical Resistance: Thinkers like Jean-Jacques Rousseau argued that humans are not naturally malicious; rather, it is the corrupting structure of modern civilization, property rights, and artificial inequality that make us predatory toward one another.

• The Evolutionary View: As evolutionary theorist Peter Kropotkin argued in Mutual Aid, cooperation, empathy, and community building are just as foundational to human survival—if not more so—than raw competition.

Ultimately, the phrase functions less as a biological fact and more as a diagnostic warning: when social contracts break down and systemic structures isolate individuals, we are entirely capable of turning on one another with terrifying efficiency.