It’s quite common for stupid and self-righteous conservatives to object to student loan debt cancellation on the basis of “personal irresponsibility”, moral hazard, and the fact that the student signed the loan contract. But as Zippy Catholic points out, Thomas Aquinas conclusively answered that objection a long time ago.
Accordingly we must also answer to the question in point that it is by no means lawful to induce a man to lend under a condition of usury: yet it is lawful to borrow for usury from a man who is ready to do so and is a usurer by profession; provided the borrower have a good end in view, such as the relief of his own or another’s need. Thus too it is lawful for a man who has fallen among thieves to point out his property to them (which they sin in taking) in order to save his life, after the example of the ten men who said to Ismahel (Jeremiah 41:8): “Kill us not: for we have stores in the field.”
– Thomas AST II-II, Q78, A4):Since borrowing at usury is inherently scandalous, it probably depends on the extent of the need. But you’ve got pretty wide moral discretion to hand over your property to thieves, so you’ve probably got similar prudential latitude here. As a matter of intrinsic morality, usury – insisting on interest when making a mutuum loan – is a sin on the part of the lender, not the borrower.
The lender is the wrongdoer, not the borrower. Therefore, there is no moral hazard created by cancelling student loan debt, unless the government then proceeds to bails out the lender. It is bailouts, not debt cancellations, that are both immoral and morally hazardous by nature.