License compatibility of MS-PL and MS-CL (Was: (RE: Groklaw's OSI item (was: When will CPAL actually be _used_?))

Michael R. Bernstein michael at
Thu Aug 23 23:48:29 UTC 2007

On Thu, 2007-08-23 at 00:01 -0700, Rick Moen wrote:
> Quoting Michael R. Bernstein (michael at
> > No, let me amend that: It bothers me that these licenses are
> > incompatible with the entire universe of all other theoretically
> > possible licenses, including future ones, regardless of their terms.
> [...]
> > It also bothers me that this incompatibility extends not just to code
> > mixing and sublicensing, but also to multiple licensing. Multiple
> > licensing, like forking, is an unfortunate and infrequent necessity that
> > I don't think should be given up lightly.
> > 
> > I think we need to add OSD #11 to disallow this kind of gratuitous and
> > discriminatory license incompatibility. 
> Nothing in open source has ever required avoidance of licence
> incompatibilities.

True. But let's make sure we're on the same page. In my view there are
four basic ways in which a license can be inflexible that may lead to
incompatibilities with other licenses:

 The license may forbid adding restrictions

 The license may forbid removing restrictions

 The license may forbid adding permissions

 The license may forbid removing permissions

In general, I have no *particular* problem on OSD grounds with
incompatibilities arising from conflicts of this nature between

In this case though, what we have is a license that says (WRT source
distributions) that no other licenses are allowed. Period. This even
excludes licenses that have otherwise compatible terms and conditions,
even those that have *identical* terms and conditions (ie. the same
license with a name change).

To me, this seems to go beyond incompatibility per-se into

> What you're saying is that MS-CL and MS-PL create an extremely
> ghetto-ish commons within which essential freedoms are available.  That 
> may be true, but it then nonetheless _remains_ a commons within which
> essential freedoms are available.

OK, this is a valid point, and I guess I haven't explained my pov
clearly enough.

In my opinion, even though arbitrary conflicts of terms and conditions
with other licenses are acceptable (if unfortunate), arbitrarily
refusing to allow code into or out of the commons where no actual
conflict of terms and conditions exists is un-free. I suppose it is
un-necessarily abridging the freedom to modify.

To continue your analogy, this is a ghetto where people may enter and
leave freely as long as they strip themselves of all possessions and
clothing, with no exceptions. Nothing is stolen, no taxes are levied,
everything you leave behind will still be there if and when you return
or exit, but you can't take anything with you in either direction. More
importantly, there is no reason for it except control-freakery. This may
fit some theoretical definition of freedom, but do you truly not see a
problem here?

> Nothing in open source has ever, to date, barred the creation of badly
> conceived commonses that will likely eventually fall flat on their
> faces.
>   The proper remedy, IMVAO, is to watch and _find out_ whether
> they fall flat on their faces.  And meanwhile, you're free to tell
> people "That's a sucky licence."  News flash:  The OSI approved list
> includes many sucky licences, already.

True, but on this list we've occasionally discouraged sucky licenses
from completing the approval process. And as I said, I think that these
licenses are not just sucky, but also mildly un-free, even though the
OSD does not currently exclude this particular flavor of un-freedom.

> > Or perhaps this: A license may not discriminate against other licenses
> > or groups of licenses.
> Nice can of worms you have there.  Make sure you have plenty of room.
> ;->

I don't really think this is a can of worms. I've repeatedly stated that
incompatibilities aren't objectionable in and of themselves. I just
think there is a difference between a license that is incompatible with
other licenses (for example reciprocal licenses) due to a conflict of
terms and conditions and one that baldly says "the GPL is excluded" or
"reciprocal licenses are excluded".

In this case, of course, what I object to is the MS-PL excluding *all*
other licenses from source distributions, which though it is certainly
even-handed in it's contempt, I still find discriminatory.

- Michael R. Bernstein
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