The only objection, then, to the new heathen, contraceptive morality will be that the second condition I mentioned - near-universality of contraception where there ought not to be begetting - simply won't be fulfilled. Against the background of a society with that morality, more and more people will have intercourse with little feeling of responsibility, little restraint, and yet they just won't be so careful about always using contraceptives. And so the widespread use of contraceptives naturally leads to more and more rather than less and less abortion.
Except that, as this report by the Guttmacher Institute shows, that's precisely the opposite of what happens. Anscombe does throw in a qualifier, granting the possibility of a strictly short-term decline in abortion rates, but then claims the long-term result will be a net increase in abortion rates. She's simply empirically wrong about that claim, as well:
Initially, rapid fertility decline in South Korea was accompanied by increases in both contraceptive use and abortion; over time [ie, 40 years], abortion rates turned downward while contraceptive use continued to climb.
But the reason why Anscombe makes this assertion is also interesting. Prima facie, `contraceptive morality' (as Anscrombe calls it here) or the `contraceptive mindset' (as some contemporary opponents of contraception call it) is nothing more or less than the view that the use of contraception is entirely permissible, morally speaking. But this is, strictly speaking, only a proper part of what these opponents of contraception mean; they also seem to think that this mindset or morality involves a sort of firm resolution to avoid taking responsibility for one's actions. That is, using contraception is supposed to be a denial of responsibility, roughly on a par with the (supposed) denial of responsibility that is abortion, and since the former is less convenient than the latter (or something), an acceptance of contraception will lead to an increase in the number of abortions. This isn't just a strawfeminist and astonishingly (given that Anscombe is an influential analytic philosopher) vague line of argument; it's a downright bizarre inversion of the core notion, motivating those of us who believe strongly in access to and education about contraception, that the use of contraception is actually one responsible way to engage in intercourse.