By assigning copyright to them, you give them the right to distribute your work under a different license. Yes, you can't take back the original license from the older code. But they could start distributing the code without respect to the original license.

>The "without limitation" part of the MIT license guards against this doesn't it?

Ah, but it reads "without limitation [...] subject to the following conditions"

Yes, but those conditions start and end at requiring attribution.

MIT already allows sublicensing, so a CLA for an MIT project (assuming nothing else shady is going on) really only buys them the ability to change future licenses to something incompatible with MIT (would that be called superlicensing?), and possibly remove your attribution in future versions.

That to me is philosophically what I want out of a permissive license, so I personally am fine with CLAs in those cases, however I can understand why some would be against that.

>Yes, but those conditions start and end at requiring attribution.

Read carefully:

>copyright notice and this permission notice

>MIT already allows sublicensing

IANAL, but sublicensing can only impose additional clauses, it cannot roll back any grants or restrictions of the original license.

Sorry, that is what I meant by attribution (which is defined as the copyright and license in MIT).

>IANAL, but sublicensing can only impose additional clauses, it cannot roll back any grants or restrictions of the original license.

Yeah, so a CLA allows that to move to a "superlicense" kind of thing (still not sure if that word makes sense there), so they could rollback those grants or restrictions of the MIT license in the future, but they cannot do so for the past.

Which, I'm okay with in a lot of cases, as that is what I philosophically want from a permissive license. However I can see how many would not be.