"... and in response to any limits on deductions it could even fall by about
the same amount as the increase in the tax bill, according to John List
of the University of Chicago,
who recently reviewed the literature on this subject. Other studies
have suggested an effect about half as large. Even that smaller
estimate, though, suggests that limiting deductions to $50,000 a year
could easily reduce giving by tens of billions of dollars."
That's former Obama administration official Peter Orszag on proposals to limit the charitable deduction.