it's important to remember that there was absolutely no application of "social security" of any form until modern times, and that many of the responsibilities now taken on board by "the State" - not least protect of the rights and care of individuals - used to be the sole responsibility of the head of household.
actually, brian, that's where you're wrong, certainly in the case of judaism and probably elsewhere too.
for a start, let's go right back to leviticus 19:9-10:
"Now when you reap the harvest of your land, you shall not reap to the very corners of your field, nor shall you gather the gleanings of your harvest. Nor shall you glean your vineyard, nor shall you gather the fallen fruit of your vineyard; you shall leave them for the needy and for the stranger. I am HaShem your G!D."
i believe this is more or less self-explanatory. similarly, verse 34:
"The stranger who resides with you shall be to you as the native among you, and you shall love him as yourself, for you were aliens in the land of Egypt; I am HaShem your G!D."
and, in terms of the "socially excluded", exodus 22:22:
"You shall not afflict any widow or orphan"
not to mention deuteronomy 10:18, 14:29. 24:17, 24:19-21. and if the pshat isn't sufficiently clear, the oral Law makes it abundantly clear that these rights for the socially vulnerable are enforceable in court. likewise, the obligations to give to charity, be hospitable and so on, are explicitly outlined and discussed:
http://en.wikibooks.org/wiki/Mishnah_Peah_1:1
in fact, if you go into the detail and study the extra obligations imposed by the Gemara and the later authorities, this reveals that the sages were anxious - some might even say overly so - to provide social care for the marginalised: not from some "head of the household", but from the community in general and at large, specifically to prevent it becoming patronage-based.
now - sex outside marriage. actually, this is seen as a slightly different issue. firstly, jewish law does not discriminate against children born outside marriage as long as the union of the parents had they wanted to get married, would have been allowed. however, it was - and remains - decidedly frowned upon for people to go from one relationship to another and engage in casual sex. nonetheless, it is clear from a study of the texts involved that this sort of thing was happening even 2000 years ago precisely because rabbinic prohibitions are generally for things which aren't explicitly forbidden; in other words, they don't bother forbidding things that people don't normally do. even nowadays, some form of sex before marriage, if not tacitly condoned, is certainly acknowledged to be common, even amongst the fairly observant - so much so, that there is a phenomenon in new york known as the "tefillin date" - in other words, you take your tefillin on the date because you know you're going to need them in the morning and you won't have woken up in your own bed!
like brian points out, the vast majority of the prohibitions are aimed at preventing children being born to parents who are not permitted to marry, because this status has very unpleasant consequences. for the same reason, it is important that divorces are correctly carried out.
it is also important, by the way, to recognise that because a woman did not belong to a man, that did not prevent her from operating as a household in her own right. women could inherit - as established by the daughters of zelophechad - and could own and operate businesses. they were not chattels.
b'shalom
bananabrain