[Revised entry by Michael Nelson on May 5, 2020. Changes to: Main text, Bibliography] Existence raises deep and important problems in metaphysics, philosophy of language, and philosophical logic. Many of the issues can be organized around the following two questions: Is existence a property of individuals? and Assuming that existence is a property of individuals, are there individuals that lack it? What does it mean to ask if existence is a property? A full answer to...

We speak with Dr. Richard Levitan, an emergency physician based in Littleton, New Hampshire, who volunteered at Bellevue Hospital in Manhattan for 10 days at the height of the COVID-19 surge in April. Based on what he saw, he argues patients should be going to hospitals sooner and that medical professionals could use a small device you clip on your fingertip, called a pulse oximeter, to help detect the virus earlier by revealing oxygenation problems and elevated heart rates. "A pulse oximeter is just a measure of identifying how well the lungs are working, and, I believe, can be basically an early warning system in terms of patients to know who has COVID pneumonia," says Dr. Levitan.