When you're using FOL, there is an understanding that it's not trying to literally describe the world accurately-- it's an idealized version to demonstrate logi

When you're using FOL, there is an understanding that it's not trying to literally describe the world accurately-- it's an idealized version to demonstrate logical thinking in a way that's easier and more intuitive than only using symbols like P or Q. So when there is a syllogism involving "All birds can fly," no one is seriously claiming that there aren't any birds that have damaged wings or that are too weak to fly.