An email:

Good op-ed. A couple quick thoughts for what they’re worth (eg, what you paid for them):
1. To ‘buy’ lower marginal rates for high earners the GOP has had to take more and more low/middle earners off the rolls. Other than payroll taxes there’s not much more to offer these folks, so the political saliency of tax cuts was bound to run down. Now we’re stuck with penny-ante stuff.
2. Re Dan Mitchell’s point: There’s no particular theory of long-run economic growth by which tax cuts are big drivers. (Eg, the Solow model or Mankiw-Romer-Weil) If, say, we cut the tax on high earners so they work more, you’ll immediately shift to a higher labor force participation rate and therefore higher economic output. But it’s basically a one-time event: GDP will always be higher because we’re working more, but the growth rate of GDP will go back to where it was before. With higher savings there’s a longer period of slightly higher growth until you reach the steady state, but the effects are still pretty modest. In long-run growth models it’s technology that’s the real driver; for that you could subsidize research, improve patent policy, etc.
3. If a child tax credit increases the birth rate (which is plausible — see this article on France, which now has a birth rate almost as high as the US: http://www.washingtonpost.com/wp-dyn/content/article/2006/10/17/AR2006101701652.html) then it will increase long term economic growth since babies eventually become workers. Workers paying into, say, Social Security and Medicare. If parents invest more in the human capital of their kids that would also help; if the tax credit helps parents stay home with their kids that could contribute, though you might want more targeted measures as well.

And another email:

I am a tax partner with a downtown Baltimore law firm who graduated from U.Va.’s law school and N.Y.U.’s LL.M. in Taxation program and I agree . . . that the Child Tax Credit against the federal income tax should be expanded in two ways. First, it should not be phased out as parents earn more than approximately $120,000. Second, it should be increased from $1,000 to $5,000 per child per year.
One of the considerations underlying good tax policy is to spread the burden of taxation so that it is equally burdensome on all taxpayers who are similarly situated. This is what is called horizontal equity. Parents have significantly greater expenses to bear that must be paid out of their incomes than do people who have no children. In other words, two taxpayers who earn the same amount of income but have different numbers of children are not similarly situated taxpayers and the taxpayer with more children should pay significantly less tax as a matter of good tax policy. Our society is counting on middle class, upper middle class, and upper class citizens to have enough children to keep our Social Security system and our general social contract going indefinitely off into the future. By not adequately taking into account the fact that children raised by middle class parents are extraordinarily expensive (and extraordinarily valuable to society over the long run) our tax system is discouraging taxpayers from having children. Other countries have adopted small baby bonuses and have seen a modest increase in fertility and child-rearing among its middle and upper classes. We should adopt similar policies but be far more generous than any country has dared so far.
I like using a non-refundable income tax credit as the tool for furthering a pro-natal policy because it would only serve to encourage families who would otherwise be paying federal income tax and will not encourage non-income taxpayers to have more children. Additional middle class, upper middle class, and upper class children will eventually translate into additional taxpayers who will be supporting this society far off into the future. Our nation’s birth dearth of middle class, upper middle class, and upper class children is a far more important long-term problem to our nation than our high marginal corporate income tax rates retarding economic growth. (By the way, we could fix the corporate income tax rate painlessly by excluding dividends from the measure of income. U.S. corporations already pay very little in the way of dividends and exempting this money from the measure of income would barely affect the federal government’s income tax receipts but would go a long way toward improving corporate governance and equalizing corporate tax rates with the rest of the industrialized world.) This additional high quality human capital developed from domestic sources would come on line beginning in about twenty-five years and would be extraordinarily good for our nation’s long-term economic growth thereafter.
Alternatively, we could provide for a holiday from FICA and SECA taxes while an individual is entitled to count more than two minor children as dependents. This would be a broader exemption because everyone pays Social Security associated taxes and the Social Security system is part of the reason why our society is so concerned about a birth dearth. I prefer an income tax incentive to this approach but would be willing to settle for this because the benefit from such a social insurance tax holiday would be limited to parents who earn wages.
In addition to being good tax policy, providing tax incentives for taxpayers to have children is also good politics for the Republican party. Families with children are way more likely to vote for the G.O.P. than for the Democrats. However, the Democrats cannot effectively demonize families with children when they argue against this kind of tax policy. I see advocating this kind of change to our tax laws as a win-win situation for everyone who cares about long-term economic growth and the future of the G.O.P.