So, some more political philosophy-related thinking out loud. G. A. Cohen, as part of his internal critique of Rawlsian principles of distributive justice, has maintained that moral obligations cannot troublingly reduce freedom because either moral obligations do not reduce freedom or they do not troublingly reduce freedom. For example, we all have a moral obligation not to murder other people. If this obligation does reduce each of us's freedom, surely it does not do so troublingly. Thus, Cohen claims, the egalitarian ethos requiring those with rare and productive talents not to seek incentives for making use of those talents, if it is a moral obligation, does not troublingly reduce freedom.
There are a number of ways of interpreting this claim. The claim could be true if all moral obligations did not reduce freedom at all. I take this to be false, since people seem to experience some moral obligations as coercive - the obligation to devote their lives to looking after sick relatives, for example. The claim could also be true if all moral obligations did reduce freedom, but did so untroublingly. I also take this to be false, since people seem to experience some moral obligations as non-coercive - the obligation not to murder, for example. I'm not going to argue further for either of those claims, since I think they're reasonably plausible, and what I'm arguing may depend on them being granted the status of assumptions.
This means that Cohen's claim can only be true if some moral obligations do not reduce freedom and all the rest do not reduce it troublingly. Presumably what distinguishes between the obligations which do not reduce freedom and those which do not reduce it troublingly is their weightiness, that is, how burdensome it is to fulfill them. Thus, the obligation to devote one's life to looking after a seriously ill relative is very burdensome, and so we think it reduces your freedom, even if we think it does not do so troublingly, i.e., that, all things considered, it is not an unreasonable thing to ask you to do. Conversely, the obligation not to murder people is not very burdensome, since it leaves you able to pursue all kinds of other projects in all kinds of other ways, and so we do not think that it reduces your freedom.
So, how burdensome an obligation is determines whether or not it reduces freedom. Burdensome obligations reduce freedom, and less burdensome ones do not. The question then becomes whether a burdensome obligation reduces freedom troublingly. Presumably a burdensome obligation does not reduce freedom troublingly if what fulfilling the obligation will provide is very important; the important goal that the obligation serves justifies the loss of freedom. A less important goal for an equally burdensome obligation though, would reduce freedom troublingly, since the goal no longer justifies the loss of freedom, and, on Cohen's logic, would no longer be a real obligation but only a putative one, one that on investigation we found out was unjustified.
Thus, on Cohen's logic, we have a doubly dichotomous account of the relationship between moral obligation and freedom. There are moral obligations we have which are not burdensome enough to threaten freedom, and a set of putative moral obligations which are burdensome enough to threaten freedom, some of which are genuine moral obligations because the goals they provide for justify the loss of freedom and some of which are not because the goals they provide for do not so justify the loss of freedom. It is implausible to think that all moral obligations which threaten freedom are equally burdensome, so different kinds of justification for different freedom-threatening moral obligations will be needed. What we need to justify the obligation to look after a sick relative for three days a week will be different from the obligation to look after a sick relative all the time.
That means that before deciding whether a putative freedom-threatening obligation is justified, we need to consider the relative weights of the goals fulfilling it provides and the burdens it imposes on the person who bears it. That means that we need to engage in moral argument before we can decide that some putative obligation is indeed an obligation. This is what Cohen wants to prevent by appealing to the claim that moral obligations either do not threaten freedom or do so untroublingly. If, though, one has to consider a putative obligation's effects on freedom before deciding whether or not it is an obligation, then this response is not adequate.
Neither is it good enough to say that it is the same obligation as to set up and sustain a basic structure - a set of political and socio-economic institutions like property rights and tax law - which abides by the Rawlsian distributive principles in question. This is because the burdens the obligations impose are not the same; the burdens, and so the content of the obligation in question, of a system of care for the sick paid for out of general taxation and provided for by professionals against a background of free career choice are different from the burdens of a system of care for the sick provided on a individual basis (this whole post may be a roundabout way of making this point). Hmm. I'm not sure whether this would also apply if the claim that there has to be a spectrum running from non-freedom reducing to acceptably freedom-reducing were withdrawn.