Type erasure erases they correct type information of paramatized types and replaces it with its super. Call get class on the object it reports the wrong information. This means you can load any type with the same super or that super type into a collection or to a refrance from persistent data. No error until you try to access a method on the bad object. Type erasure produces incorrect run time information, breaks the rules of inhieretance, and destroys the type saftey of the language. The only arguments i have heard so far for it are "no language is perfect", "we need a solution that works with legacy code", and "its better than ". The first and third arguments, well... some real visionaries, huh? That second dog just don't hunt. Type erasure does not play well with legacy code. Imagine trying to find the line of code that crashed your program when your error is thrown in a completly different place. It was a bad move that cannot be taken back. I think time will show that developers will choose a more reliable and logical solution that behaves predictably.