Objection 1: Argument Depends on an Implausible View of Ideal Theory

My definition of navigational ideal theory places no constraints on the time period relevant to the ideal theorist, implying that they must look indefinitely into the future when determining the most just society possible. Some will find this conception of ideal theory implausible because it makes impossible demands on political philosophers. No one can fathom what society could look like millennia from now. We therefore should understand ideal theory as proposing a goal for a more limited time horizon, which is often the case in practice. John Rawls, for instance, sets forth an ideal suitable for today’s liberal democratic societies characterized by pluralism and moderate scarcity, wasting no time on futuristic scenarios. Ideal theorists typically offer a vision of the most just society possible with a medium-term time horizon in mind – one lasting a few decades, not millennia. According to this view, if ideal theory provides a medium-term goal, it is unfair to criticize it for failing to foresee further ahead.

This objection, though reasonable, fails for two reasons. First, it undermines a primary argument for ideal theory. Defenders of ideal theory argue that it provides a goal to guide action and avoid paths away from the most just possibility.Footnote ¹ Ideal theory cannot fulfill that role, however, if it only offers a medium-term goal. The most just society possible in the next 25 years may look much different than the most just society possible in 250 years. The challenge of climate change illustrates this point. If we adopt a medium-term time horizon from the perspective of 1900, heavy reliance on fossil fuel seems compatible with the ideal society given industrialization’s role in significantly reducing poverty and mortality rates. But if the time horizon is extended, that proposal becomes more problematic given the dangerous impacts on the climate that dependence on fossil fuels eventually causes.Footnote ² In the long-term scenario, it is critical for ideal theory to consider questions related to climate justice, but they have less relevance in the medium-term scenario.Footnote ³ As this example shows, pursuing the most just society possible in the medium term can take us further from the most just society possible in the long term – an outcome at odds with ideal theory’s purpose. To focus on a medium-term ideal, while putting aside long-term considerations, involves abandoning a core commitment of ideal theory.

Second, even if ideal theorists limit their time horizon and focus on a medium-term ideal, there is little reason to believe they can plausibly defend this less ambitious ideal. As discussed in Chapter 6, human predictive capacities decline drastically when trying to make predictions about society as little as five to ten years into the future. A medium-term ideal for the coming decades and century still falls outside that narrow window. The ideal theorist trying to defend a medium-term ideal has to make predictions about the world at the time when their principles of justice could be implemented, but they cannot make these predictions with reliable accuracy. As a result, they cannot plausibly defend their theory. Ultimately, ideal theory focused on a medium-term ideal falls victim to the same problems plaguing more ambitious forms of it.

Objection 2: Argument Wrongly Assumes Ideal Society Cannot Arrive Soon

The argument against ideal theory’s plausibility assumes the potential for greater justice in the distant future, which puts ideal theorists in the impossible spot of trying to predict what their principles of justice would look like in a future society. Perhaps, though, the ideal society could come much sooner. That possibility is more likely with ideal theories that take society to be perfectly just whenever it satisfies certain principles of justice, in contrast to consequentialist theories that allow justice in society to increase indefinitely as, say, happiness increases.Footnote ⁴ According to the former view, what makes society ideal is not dramatic innovations and discoveries that improve welfare, but meeting certain defined criteria (e.g., protection of basic liberties and fair distribution of wealth). Though major injustices must be overcome, the ideal society may not be so distant from the present. That attitude sometimes appears in Rawls when he describes ideal theory as offering a “reasonably just” society to strive and hope for.Footnote ⁵ Such language implies a modest goal potentially within reach. If so, ideal theory seems to be in a better position to defend itself, since explaining the social realizations of its principles would only require short-term predictions.

Though this objection tries to absolve ideal theorists from having to make long-term predictions, it fails to. Even if an ideal theorist gives plausible grounds for accepting and striving after an ideal in the short term, that defense says nothing about its moral appeal for the long term. A society that best promotes justice now but leads away from greater justice in the future hardly counts as ideal. To be plausible and compelling, a defense of ideal theory must show that its ideal is an end goal that will possess moral appeal far into the future, which does require long-term predictions. So regardless of whether the ideal society can arrive soon or only in the distant future, the ideal theorist cannot avoid the need for long-term predictions. Since these predictions are unreliable, in both cases defenses of ideal theory lack plausibility.

Objection 3: Argument Fails if Prediction Improves

There is a certain irony in using evidence of our inability to predict the future to then predict the future, which in effect is what the argument against ideal theory’s plausibility does. It relies on research showing limitations on human predictive capacities, and infers that those limitations will continue. Some may argue that, if we take research on prediction seriously, we recognize how dramatically the world can change and never assume that past trends will continue. Though people currently do little better than dart-throwing chimps in making long-term predictions about society, things could change. Perhaps the future holds the Black Swan to end all Black Swans – some unforeseen event that renders the world far more predictable. That change would put premise (3) of my argument in doubt and potentially open the door to plausible defenses of navigational ideal theory.

In response, it is tempting to argue that uncertainty is the one thing we can be certain about, given the world’s complexity. But defending that position is unnecessary. It suffices to note that the Black Swan to end all Black Swans clearly has not arrived yet. Even if such an event occurs in the future, it does nothing to change our inability to plausibly defend ideal theory now. To defend ideal theory in the present, we first need an accurate understanding of future conditions where an ideal theory’s principles could be realized. If we ever gain that, political philosophers will have reason to revisit the project of defending ideal theory. But as long as severe limitations on prediction persist, defenses of ideal theory necessarily fail.

Objection 4: Argument Does Not Apply to All Forms of Ideal Theory

My argument applies specifically to navigational ideal theory, but leaves open the possibility of plausibly defending other forms of ideal theory. So perhaps the argument is not so damning. It is true that my argument does not apply to ideal theory that outlines justice in idealized worlds. If ideal theorists engage in thought experiments involving fictional worlds without Black Swans, it indeed becomes easier to explain the social realizations of their principles of justice and defend them.

It hopefully is clear that, in focusing on navigational ideal theory, I am not constructing a straw man to tear down. Ideal theory often attracts attention because it purports to have navigational value. If ideal theorists viewed their theories as intellectual pursuits irrelevant to guiding action, the stakes would be lower and their work would provoke less debate. But the most influential accounts of ideal theory do claim to have normative value. Rawls believes ideal theory offers an objective to guide social reform,Footnote ⁶ calling it a “realistic utopia” that “is feasible and might actually exist, if not now then at some future time under happier circumstances.”Footnote ⁷ In its most normatively compelling form, ideal theory concerns itself not with impossible ideals irrelevant to advancing justice, but with ones suitable for guiding action in the real world. Navigational ideal theory, by focusing on a feasible end goal, represents the strongest candidate for fulfilling the normative ambitions that Rawls and others assign to ideal theory. The argument outlined here shows that, even in its most promising form, ideal theory fails to offer what so many want from it – a compelling and plausible ideal to guide collective efforts in advancing justice.