[the_mitsuhiko]

Those numbers are completely useless because they don't question the reliability of condoms but the more social aspects of it (eg: how good are people on average in using them). If you are capable of using birth control then they will work just fine to prevent a pregnancy.

[bobthechef]

They're also percentages with no actual absolute numbers. People often interpret percentages while falsely assuming that other things remain constant. For example, if condom use is accepted and people come to believe condoms work, they may be more likely to have sex more frequently because their fear of contracting STDs and pregnancy have decreased. This means that the failure rate no longer pertains to the original frequency of sexual intercourse but the new one. This way, the number of actual failures (vs. just the rate) may exceed the original, and with it the number of abortions. This way, condoms actually enable the behavior whose consequences they were intended to limit. Yay, big picture.