One of the Roman Catholic arguments that is popular is the argument that Scriptures alone are insufficient as our rule of faith and life, because they do not explicitly (or perhaps even implicitly) address issues that allegedly did not exist at the time Scripture was written. Usually topics like birth control are broached as the issue to be addressed.
Steve Hays has provided an excellent, if somewhat amusing, rebuttal by pointing to Islam as an example of a religion that seeks to regulate a much deeper amount of people's lives than even Catholicism (link to rebuttal). One way to apply the rebuttal is that if Catholicism is supposed to be an exhaustive rule is by showing that there are many questions it does not answer, such as whether it is appropriate for a woman to be alone in the same elevator with a man who is not part of her immediate family.
If Scripture's alleged failure to answer the question of stem cell research is a problem, why isn't the failure of Catholicism to tell us which side of our body to lie on at night a problem for Catholicism?
And there is really no need to limit ourselves to the extremes of the Muslims or Jews - where is Catholicism's answer as to whether I should buy Pepsi or Coke? And if I find myself in an elevator that is playing music by Britney Spears, am I permitted to stay on the elevator as long as I don't allow myself to enjoy it?