Susan Moller Okin argued against the theories of Rawls, Nozick, MacIntyre and others. Why? can you be more specific to where I might be able to find the answer.

Rather than simply going to www.google.com and searching (and praying for an answer!), you need to try searching in all of the following:

http://www.google.com/advanced_search?hl=en

http://scholar.google.com

http://books.google.com

For example, when I used the first link and entered her name in the SECOND box (exact phrase), here are the results:
http://www.google.com/search?hl=en&as_q=&as_epq=+Susan+Moller+Okin&as_oq=&as_eq=&num=10&lr=&as_filetype=&ft=i&as_sitesearch=&as_qdr=all&as_rights=&as_occt=any&cr=&as_nlo=&as_nhi=&safe=images

Try entering her full name in the other two search sites, too.

Once in a search results website, press Ctrl + F and a little space will appear where you can type a word you want to isolate. Type Rawls or Nozick or MacIntire or whatever you need in that Find box. It'll let you know if there is reference to that person on that particular webpage.

There are many elements to searching and finding what you need. Don't rely only on www.google.com.