Megan McArdle’s evisceration of the idea that government subsidies for contraception have been proven to reduce abortion rates is something every conservative should study and take notes on. I commend the whole piece, especially her conclusion on one of the most-cited studies in favor of the more-contraceptives-less-abortions argument:

[The researchers] tell you that Colorado gave out LARCs [long-acting reversible contraceptives]; they tell you that birthrates and abortions fell. They don’t dwell on the simultaneous fall in these areas at the national level, which is somewhat mysterious but may be fallout from the financial crisis. They have no way to establish causality except for an inadequate control group that doesn’t even show a substantial difference in teen abortion rates, a fact that they appear to have forgotten in other sections of the paper. (They also mention that the overall decline in Colorado’s birthrates was concentrated among low-income women in the studied counties, but that’s not actually very interesting, because early motherhood and unintended pregnancy are also concentrated among low-income women.)
The authors basically concede that they cannot come close to establishing causality, because the summary conclusion is a weasel: LARCs may contribute to a decline in fertility and abortion among high-risk women. How much? We don’t know, but look at the pretty graphs!

A lack for appreciation for just how difficult it is to produce good research is among the most dangerous aspects of the study-loving, “Science!” boosters on the left. Conducting a rigorous, well-researched, falsifiable experiment that holds up to scrutiny and offers anything approaching a meaningful addition to human knowledge is devilishly difficult under the best of circumstances. It’s massively more complicated when one’s subjects are thinking, adaptable, stubborn, difficult-to-control human beings.