In January 2026, President Donald Trump told an audience of business and political leaders in Davos, Switzerland, that the United States needed the “right, title and ownership” to Greenland “because you need the ownership to defend it. You can’t defend it on a lease.”

A territory of roughly 57,000 people appears to the president as property to be acquired.

Trump’s various actions during his second term have prompted no shortage of explanations. The “flooding the zone” strategy treats his flurry of executive orders and legal battles as efforts to overwhelm the courts’ and news media’s ability to keep up. Psychological explanations of Trump’s behavior point to narcissism. Other political commentators interpret his actions through authoritarianism and demagoguery.

I believe these accounts overlook something simpler. Before entering politics, Trump spent five decades running a commercial real estate business. In my assessment, he still reasons the way his professional career taught him to.

I study how forms of reasoning shape political arguments, and in analyzing Trump’s rhetoric across his second term, I find a president who approaches governing through the same framework as his business career – a mode of thinking I call portfolio reasoning.

Portfolio reasoning is a financial way of thinking that treats what one has – from property and money to relationships and obligations – as a collection of holdings to be continually managed and reassessed to maximize its value.

The recurring questions are familiar: What do I have? What is performing well and what isn’t? What should I keep, acquire, renegotiate or get rid of? And how do I make sure I can walk away?

Modern portfolio theory originated with economist Harry Markowitz in the 1950s as a way to........

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