Here there are two problems. First, where what is being sought is a universal system in which every individual is enrolled, the difficulty is to derive the necessity of this system from people's ignorance and uncertainty regarding their own futures and arrive at political determinations that lead to universal participation in a single system rather than individuals choosing their own private insurance - these sorts of difficulties are generally seen in social contract theory-based attempts to logically construct social systems. Without making highly improbable assumptions, it is hard to imagine everyone agreeing to such a system; there are overconfident people who have faith in their own health or luck for no good reason, and others who do not particularly care about their own futures and are willing to let the cards fall where they may. If not everyone both cares about their own future and is capable of making rational decisions regarding it, it follows that not everyone will agree to a single "social contract". More important than practical difficulties that may be encountered, here we see that even in principle it is not plausible that this approach could lead to universal participation in this kind of system. If we assume that every individual is afflicted by relatively powerful anxiety about their own future, if, in other words, we make the kind of highly improbable assumption mentioned above, then universal participation may be possible. Just as in the case of private insurance, however, this approach requires an acceptance of the principle that individuals will not enter the system unless they want to.
Second, there are also the problems that arise when the assumption of ignorance is not tenable. The logic used to support these systems of cooperation assumes that there are characteristics and abilities that cannot be controlled by the self and that cannot be known to the self beforehand. This assumption is then used to justify the division/distribution of resources as being something similar to insurance. But what happens if this assumption changes? What happens if the "risks" for each individual are understood? What happens if it becomes possible to understand the causes that determine the relevant outcomes? It cannot be denied that human characteristics and abilities are at least in part determined by innate factors. Through genetic testing it may thus become possible to predict the future of an individual (at least in the sense of being able to give the probability of certain outcomes). We would then know which individuals had a high likelihood of illness. We would know whether or not individuals were disabled before they were born. Since insurance systems with high numbers of people likely to require expensive care would have high premiums, those seeking lower premiums would not enter insurance systems with large numbers of high-risk participants. As a result, high risk individuals (or their parents) would be denied insurance or charged higher premiums.
These kinds of problems are already starting to emerge. ［…］