On the impossibility of Rawls' realistic utopia
Some may object to Rawls's idea of a reasonably just constitutional democratic society by insisting that this type of society is pure fantasy. A compelling reason for believing in Rawls' realistic utopia has to do with a view that a better, or best of all, possible world exists. The trouble is that this world seems to show that we may be incapable of having the better possible world come to pass. Let's just think of our own world and some of the events of the past century or two. Dreadfully evil events, like the Holocaust and the Inquisition for instance, prove that the hopes expressed by Rawls's realistic utopia are fantastic. Even more than this, we are only now coming to realise the tremendous social injustices and horrifically bad behaviour characteristic of the age of empires when Britain and other western European countries pillaged and plundered their way through countries in Africa, South America, and Asia. All of these events seem to play against Rawls' views.
Rawls presents an awkward argument to defend himself against this objection to his pollyannaish vision of a realistic utopia. He seeks to argue that past and present evils fail to undermine hope for the future of a society as belonging to a Society of liberal and decent Peoples (Law of Peoples, p. 22f). Whenever we consider whether the future will be better than the past, we oftentimes find ourselves agreeing that it will. The future is always better than the past! Our best days are ahead of us, so the old saying goes. Yet, there are at least two reasons to believe that this vision is false. Not only may new technologies yield harmful consequences but the human condition itself seems to be worsening, that is, people are thinking up new and more problematic ways of treating others badly.
Too often we think of new technologies as helpful and important for advancement. However, it is not unreasonable to believe that new technologies could yield new means of harming one another. Given that many new technologies provide us with new means of harming others, it is reasonable to suppose that one reason for not taking up Rawls' realistic utopia has to do with the harms that could befall us from technological advances. The view that we should be optimistic about the future is easily undermined by this idea.
Second, the human condition itself shows that people do not begin with treating others equally for no reason. Instead, people are far more likely to treat others in adversarial ways. We think of others as competitors with us. For this reason it is easy to believe that our views of others have been tainted and that this has laid the groundwork for us to treat others differently. We think of people as subhuman or treat them inhumanely.
Ultimately, his argument rests on the idea of the "reasonableness" of the Law of Peoples. There are two ways we could interpret "reasonableness." The first way is that any reasonable person would agree that x is reasonable. There is something fundamentally true or fundamentally valuable about x that makes it reasonable. The second way is that given a, b, c, etc., x is reasonable. In this case, reasonable means that if certain conditions are met, then we consider x the most plausible or most reasonable.
If Rawls uses the first sense of reasonable, then his view has not addressed the fantasy charge. If Rawls uses the second sense of reasonable, then his view fails to have any force. Rawls's idea of "reasonableness" is not clear.