One of the interesting dialectical pivot points in recent discussions we've had about employment discrimination is charity. At some point our Christian culture degenerated to the point where "charity" started to mean "acts which are nice to do but always optional". Another thing which seems to have come along for the ride is that charity has become more abstract: the notion seems to be that charity is a marketplace selection of opportunities from which we can arbitrarily choose what we want.
In the discussion on natural obligations employers have toward the men providing for families who work for them, this has manifested in two ways.
The first way has been to treat the contingent obligation an employer has to provide for the basic dignity and needs of employees, and in turn the loyalty and diligence that an employee owes to his employer, as optional: as things not required as a matter of reciprocal justice, but rather as gratuitous and completely optional gifts.
The second way this notion has manifested itself is in the idea that charity (and therefore justice) is fungible: that there is no particular charitable obligation of employer to employee in justice but rather that the employer's obligation is just to some abstract charity-in-general, an obligation (to the extent it is one at all: see the previous point) which can be discharged by giving to one of any number of charitable opportunities in a marketplace of opportunities.
Contra all this, it seems to me that while some acts of charity - indeed the best kind - are truly gratuitous, charity in general is not optional. In addition, many or perhaps even most obligations in charity arise in particular contexts; and particular obligations cannot be discharged by "giving at the office". They have to be discharged here, now, in the context and connected to the actual persons with respect to whom they arose.
In short, the notion that charity and justice can be sawed into two utterly distinct realms is a false notion. And it is the height of foolishness to base our moral understandings and public policies on falsity.