Is the BSD2 license copyleft?

Almost every time I read about the BSD2 license it is described as being a permissive license, and that is often put into contrast with copyleft licenses like the GPL. And of course the BSD2 is more permissive in that it allows for binary only distribution. But that doesn’t mean that it is not copyleft I think. Afterall, this is the text of the license:

    Copyright (c) <year>, <copyright holder>

    Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

        Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
        Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.[12] 

The BSD2 license demands “Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.” I think that means that all derivative works must be licensed under the BSD2 :wink:

This is the first time I’m ever reading anything like this interpretation. I can’t agree with it.

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Even ‘weak’ copyleft licenses obligate users to release their changes, (modifications) which BSD doesn’t do. So, your interpretation would suggest a category of copyleft that is maybe, ‘para-weak’?

Philosophically, I think your question is shaped something like:

Is 1 grain of wheat, a heap of wheat?

The problem is because ‘copyleft’ is a vague concept.

What I meant is that I don’t think that it is sufficiently clear that the line

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

is NOT part of the “above copyright notice”. The only way to know that it is separate is whitespace. Can no one else see the potential for ambiguity and alternate interpretation?

Well, a ‘Copyright notice’ in most jurisdictions AFAIK are defunct because of the implied license due to the adoption and implementation details of Berne Convention . Prior, the convention was to format an attribution as a single line such a:

© 2012 Jane Doe

No matter, even given a radical interpretative shock, nothing here suggests to me, a non-expert and BSD-2-Clause could be sensibly or informally categorized as copyleft.