Regarding the shmita year in which the Israelites were not to sow or reap, God says he'll provide a bumper crop the year before to tide them over. "I will order my blessing for you in the sixth year, so that it will yield a crop for three years."
Does this make Judaism capable of empirical verification or falsification? If the sixth year doesn't yield three times the normal amount, is Torah disproven? Or is that a sign from God that he isn't requiring the observance of shmita that year?
The best answer, IMO, is the one that Jay gave: most of us aren't literalists. That simple, end of story.
But if you want to know the traditional midrashic answer-- at least the one I was taught-- it's that the blessing of the increased crop only happened in those years when all the people were faithfully in observance of all the commandments. But in any case, shmita was only a commandment within the Land of Israel, not in Jewish settlements outside the Land of Israel; and historically, most authorities have ruled that since the proper count of the shmita cycle was lost in the Second Temple Period, even in the Land of Israel we no longer keep shmita, since we cannot know which is the correct year.
Among some of the religious Zionist and most of the Charedi communities living in Israel, there are those who say they have come up with the appropriate calculations, and thus those communities now largely keep shmita years. But their conclusions are hardly ironclad, and there is ample room for debate. I expect that in those communities, though, the absence of the blessing of the increased crop is largely blamed on all the non-Orthodox Jews, or non-Charedi Jews, or secularization, or women sitting too far forward on the bus, on some such, for which they presume God withholds His miraculous blessing.
