Metaphysical Necessity What Must Be True in All Possible Worlds

This is a cross-group event with Philosophers & Gamblers.

What does it mean to say that something is metaphysically necessary? Are there truths that hold not just here and now, but in all possible worlds—truths that couldn’t be otherwise?
In this discussion, we’ll explore the philosophical concept of metaphysical necessity, a notion central to modal logic and metaphysics. Drawing on the work of Saul Kripke, Alvin Plantinga, and David Lewis, we’ll ask:

• What kinds of truths are necessarily true—logical, mathematical, or identity statements?
• How do metaphysical necessities differ from logical and physical necessities?
• Is "Water is H₂O" a necessary truth? What about "2+2=4"?
• And how can we even know what’s necessary across all possible worlds?

We'll also touch on the controversial idea of essence—the view that things have essential properties that ground necessity—and how this interacts with debates about reference, identity, and contingency.
No formal background required. Whether you're new to modal metaphysics or have wrestled with necessity for years, come join the inquiry.