Very much back in the day, Theseus was the mythical king of Athens. And among his many possessions, he had a ship that he used to return from slaying the Minotaur. After his death, this ship was preserved for hundreds of years in the harbor of Athens. Or was it? Whenever a wooden plank rotted out, it was replaced. If a beam fell apart, a new one was fashioned in its stead. After enough time had passed, every part had been replaced. So now it was a boat that looked very much like the ship of Theseus, and occupied the same spot in the harbor, but not a single piece of it had existed when Theseus sailed. Essentially, it was a replica. And yet people persisted in referring to this ship as the ship of Theseus. In philosophy, this problem of identity has become known as the Ship of Theseus paradox.
To make the analogy abundantly clear: sports teams change from year to year. These days, they change a lot. You might hold a great attachment to the 2004 Red Sox World Series champions, but only around 10 percent of this year's roster consists of players from that team (actual fact!). And if you have been rooting for the Sox for more than 14 years, you're rooting for a fully replaced team - different players are playing the game, different owners get your ticket money. You can see why this is an absurdity. ...
So walk with your [head] held high, you fair-weather fan! If someone besmirches your team of choice simply because your family has not been wearing its merchandise for generations, you may unleash the full force of impeccable logic upon them, starting with your fists. Mine are named Plato and Aristotle.
--Samuel Arbesman, Boston Globe, on why sports fandom is illogical