If we are unfamiliar with the context of the parable, we assume that the steward is randomly making up percentages in verses 5-7. Actually, though, he has already done the math behind the reductions he cites to each debtor. In first-century Palestine, the riskier the commodity, the higher the interest. The interest on oil was 50 percent because it could easily be spilled or spoil. The interest on wheat was 20 percent because it was a more stable commodity.
While there is desperation in the steward's action, there is also premeditated, self-interested shrewdness. He calls the debtors in one by one, not giving them the chance to compare notes and collaborate against him ahead of time. He knows that his reduction of what they owe will not ensure their permanent goodwill and hospitality toward him. At best it may postpone his poverty for a short time as they invite him to a couple of meals. He may be hoping that the master cannot blame him for not extracting the interest, since to do so would be an admission that his steward, with his blessing, had been condoning charging interest, in violation of the Torah. He may be hoping his actions could make it possible for him to secure another position as a steward for another member of the landowning elite, thereby saving him from a life of hard labor.
A better outcome still is the one that actually occurs, according to the parable. The actions of the steward please the debtors who now owe the master less. His actions please the master who takes pride in the shrewdness of the steward and who, besides, is now on the receiving end of goodwill from the debtors. With this proof of his shrewdness, the master can now retain him, enjoy the goodwill of his debtors, and, eventually, no doubt, find a way to recoup his temporary losses.
An understanding of the social, economic setting of the parable may clarify its inner dynamics. But does that help us understand its relevance for us? Luke, with his characteristic concern for the prudent use of money, seems to place after this parable a group of sayings that narrows its focus to the responsible use of wealth (16:10-13).
I'm not convinced the parable is only or specifically about the use of wealth. I think it is more broadly about the need to take shrewd, decisive action to prepare for the coming judgment. That action begins with a realistic assessment of our situation, the bed we have made that we are now lying in, the future that awaits us if we do not act to prevent it. It issues in a plan calculated to ensure a more positive outcome to our situation than we probably deserve.
The parable's commendation of shrewdness needs to be viewed in the larger context of Luke's emphases on God's mercy, Jesus' concern for the poor, and the reversal of fortunes that come with the kingdom of God. One's own best interest, in that larger context, is to act compassionately toward the poor and those who are suffering and to refrain from making wealth the goal of one's life.
In that context, clearly it is not shrewd for someone with wealth and power to be indifferent to those who are poor or on society's margins, much less to oppress them for one's own continued gain. While such actions may be undertaken to secure one's material future, in reality, such a state of living precipitates a crisis in one's condition in light of the kingdom to come. It leads to poverty and death, figuratively and literally.
On the flip side, it is shrewd for one who is being taken advantage of to seek justice by opposing the unfair practices of those in power. It is shrewd for someone with resources and influence to advocate for the disadvantaged. Whatever rung we are on in the social, economic ladder, we need to take immediate, decisive, shrewd action to secure our future, and no one can take that action for us. We must do it ourselves.
William R. Herzog II, Parables as Subversive Speech: Jesus as Pedagogue of the Oppressed (Westminster John Knox Press, 1994).
Alyce M. McKenzie, The Parables for Today (Westminster John Knox Press, 2007).