http://onlinelibrary.wiley.com/doi/10.1111/j.1467-9477.2007....
He does not support the conservative interpretation of his work that "diversity is bad":
http://chronicle.com/blogs/percolator/robert-putnam-says-his...
This is a bit of a semantic leap. Putnam objected to the use of his brief to support a lawsuit against race-conscious admissions. The article describes this brief as representing Putnam's work without the "diversity isn't always bad" disclaimer. That's a far cry from using it in a simplistic argument to say diversity is bad.
The question on the table is about race-conscious admissions. If one side's position is that using race-conscious admissions is good because it improves diversity and diversity is good, period, then challenging that premise is a perfectly valid use of Putnam's research, however Putnam might personally feel about matter.
In the article, Putnam himself is quoted as saying:
In the short term, he writes, there are clearly challenges, but over the long haul, he argues that diversity has a range of benefits for a society, and that the fragmentation and distrust can be overcome.
Great! But how the hell are you ever actually going find solutions to those challenges if you aren't allowed to bring up points like this in any situation where it might actually make a difference? And what are those benefits, exactly?
The fundamental offering that diversity brings to a society is plurality of opinion. This presents us with a mildly interesting paradox: a segregated society has no use for plural opinion, but a highly integrated society flat-out lacks them: diversity is the middle ground at which plural opinion is available.
As an aside, mainstream "controversy" is a segregated-society phenomenon, not a diverse-society one. You can tell the three kinds by their reaction to a reasonable alternative: a segregated society reacts with hostility or contempt; a diverse society reacts with toleration or moderation; an integrated society reacts with confusion or ignorance.
What a delightful thought experiment! In the meantime...
To be more precise, it says "diversity has drawbacks."
An important distinction, because when side A says "diversity is good" and side B says "diversity has drawbacks," then side A can come back and say, "well here are the benefits." Then you can compare the benefits and drawbacks and see if that helps you arrive at a better decision.
If side A says "diversity is good" and side B says "diversity is bad," then you have an intractable conflict.
Or worse, what often happens is that side A says "diversity is good," side B says "diversity has drawbacks" then side A says "side B says diversity is bad, they are evil you should not ever listen to side B under any circumstances."