What is the contradictory part of the license? And... What's the point if a license that contradicts itself? How on earth do they expect to enforce their conditions?
It's things like this that make me think "what did we do to deserve PHP?"
It's not that the license is self-contradictory, it's that the license text (as written here: http://php.net/license/3_01.txt) implies that the software is distributed only by the PHP Group, and is therefore not usable without modification by anyone outside the PHP Group. The solution is simple: modify the text of your project's license to have similar clauses to the PHP license, but not mention the PHP Group, OR re-license your software under the BSD license or another, similar license.
The solution is simple: modify the text of your project's license to have similar clauses to the PHP license, but not mention the PHP Group
That's not so simple; as a work produced by someone, a legal document may be subject to copyright. So you might need a license to the license to modify and reuse it :)
The contradictory part is that it makes several explicit references to the PHP project itself, which make no sense if applied to a project which is not PHP. In fact, this license explicitly says "THIS SOFTWARE IS PROVIDED BY THE PHP DEVELOPMENT TEAM" which is patently false for any software besides PHP itself.
The problem is that lots of other projects need to apply some license, and just for simplicity say "I'll just apply the PHP license," even though it makes absolutely no sense for anything but the PHP project itself.
I see the same problem lots with code that claims to be MIT and BSD licensed, but either doesn't include the license, or includes the license template with the placeholders for the year and copyright holder unfilled.
In the 90s it was common to see licence text refer to "the regents" even when that made no sense, but that's faded away as actual template licence text, meant to be used as a template, has become readily available.
I don't think it affected the interpretation much. If the author and the regents disclaim the warranty, and there are no regents, the straightforward interpretation is that the author disclaims warranty.
There's nothing contradictory to the license, the license is interpreted by debian's legal and FTP Masters as only allowing distribution by the "PHP Group", any package using that license which is not from "PHP group" is thus "non-distributable".
The reality is that the PHP license is a license which exists solely for PHP itself and makes no sense whatsoever for projects which are not PHP, leaving them essentially license-less and thus "all rights reserved".
It's things like this that make me think "what did we do to deserve PHP?"