So why weren’t all of the couples I know of mine, my parents and grandparents’ generations, who I know were NOT engaging in contraception, popping out dozens of children? Your stats are flawed. I don’t see any indication that they take into account the sharp drop in fertility as women get older.
And I think the answer might also lie in the ‘sex two to three times a week’. A honeymooning couple, or one intent on conceiving, may have sex that often, or even more often, but not everyone does. Just under half of married couples have sex less often than twice a week, so that right there halves, at the very least, their chances of conceiving.
And this figure in itself, since it relies on self-reporting, is probably an overestimate, as people generally don’t want to be seen as lacking in any way in the bedroom department and so will tend to say sex is more frequent than it is in reality.
Now there’s certainly no church teaching stating that a married couple must have intercourse a certain number of times a week, or for that matter even once a year! So a couple who are not practicing contraception have every chance of naturally having a lot less sex during those demanding early childhood years, and certainly are entitled naturally to tone down the frequency when they’re not actively trying for a child.
en.wikipedia.org/wiki/Infertility#Prevalence
“Fertility problems affect one in seven couples in the UK. Most couples (about 84 out of every 100) who have regular sexual intercourse (that is, every 2 to 3 days) and who do not use contraception will get pregnant within a year. About 92 out of 100 couples who are trying to get pregnant do so within 2 years.[6]”
Read that at best twice. We know, that having sex every 2 or 3 days results in 84% of cases in pregnancy in the first year.
Therefore we know that is some moral guidelines suggest to have unprotected sex every 2 to 3 days, that of 100 women following these guidelines about 84 will become pregnant. (assuming we have an average sample of women between ~20 and ~40)
So if we know what sexual behavior pattern is suggested by some guidelines, we know (!) how many preganancies are to be expected if 100 women follow these guidelines.
Thats how the argument goes:
Try to derive from catholic teaching what sexual behavior a married women, without mental or health problems and with a well earning and healthy husband, should have according to that teaching.
After deriving this (where i might have made errors, especially i missed that interest of society might play a role) the expected number of children is given by the scientific knowledge about human fertility.
Then in a third step, this is judged as unfair, because the result look limiting for the freedom of women regarding occupation choices compared to what men experience. (This is criticed by Francis as being a completely wrong apporach to the whole issue)
Regarding individual cases:
This argument never allows to state anything about individual cases. At most one could conclude something like this:
There are 100 couples claiming to follow catholic teaching and have always followed it to the letter and claim that the husband is earning more than enough well and do not suffer any psychological or health problems and are married since lets say 20 and are now 40. Yet these 100 couples have only 300 children.
=>
Some of these couples are not telling the truth regarding some matter (e.g. following church teaching, financial situation, health issues).
(And of course that reasoning gets a lot more complicated if the issues of society play a role, as according to the part i missed.)
No conclusion about any individual couple is possible.
And for this reason one cannot see the consequences of following church teachingin the real world, because nearly no one is following it consequently:
livescience.com/13708-catholics-contraceptives.html
"Catholic women overwhelmingly use birth control, despite an official ban by the church, a new study finds.
The study, conducted by reproductive health institute Guttmacher, finds that 98 percent of sexually active Catholic women use or have used birth control other than church-approved natural family planning. Only 2 percent of Catholic women have used natural family planning, which involves tracking the menstrual cycle to avoid sex during fertile periods."
But the OP argument is not about how the situation is, but what the situation would be, if church teachings regarding sexuality were followed. Therefore it is along the lines of deriving what behavior follows and what consequences this has. (Yes i know, it would also have vastly positive effects regarding criminality, wealth and diseases.)