Liberalism does not primarily concern itself with duties. As an individual-centric philosophy, it's mostly interested in specifying the rights which individuals may claim from society. Other than respecting the rights and freedoms of others (which exhausts the psychological duties to prevent harm and respect others' equality), the liberal individual ordinarily owes no ethical duties to his or her fellow citizens other than as prescribed by law.
We possess rights claims by virtue of our social membership, regardless of whether those rights are currently adequately guaranteed. Rights claims provide legitimacy for actions seeking social reform: they set standards to aspire to and by which institutions can be judged. While philosophers have occasionally grappled with defining liberal duties, in a liberal society there are prima facie no obligations on the individual which provide legitimate cause for social activism. This distinguishes liberalism from more authoritarian-attuned philosophies such as Confucianism or Legalism, nationalism or most religions, which specify universal moral duties of individuals.
Evolutionary thinking complicates this picture somwhat. Evolution is value-neutral but does establish the parameters by which ethical beliefs and culture change over time and thus limits the categories of variations that are possible (or stable) in a given environment. In this view, liberalism (as a cultural equilibrium) is simply the most widespread and flexible of possible solution sets to the problem or organising human societies at scale. While liberalism may contain cultural spandrels as a result of its particular evolutionary history (in Europe), it can be considered adaptive for a variety of social environments. Liberalism is much like the human species itself: behaviourially flexible, adaptive and relentlessly expansionist.
I think it's imperative that my colleagues at the Cultural Evolution Society give due attention to the consequences of their research for political and ethical philosophy. While almost all members I've met are genuine humanists and progressives, there are some truly nasty right-wingers who follow this material (and related subfields such as sociobiology) closely and are employing it to refine and strengthen their own ideas. As a socialist, I see it as my role to make cultural evolution and progressivism mutually intelligible: we can both agree that Foucault is full of shit without rejecting, as the right does, the critical insights of Marxism and feminism.
A late-arriving idea
The remainder of this blog is a first draft of an effort to discern if an evolutionary approach implies any ethical duties on individuals prior to liberalism, which is an adaptive product of that approach. This is an idea that crystallized for me very late in the drafting process of my book, "Politics for the New Dark Age: Staying Positive Amidst Disorder". In Chapter XVIII, discussing foreign policy, I write:
"The sole concern of the international relations policy-maker . . . is to maximise the outcomes (security) for their own state while minimising the risks arising from systemic instability. This is analogous to the task of the domestic political actor: seeking to maximise social change (or resist it, if conservative) without creating a systemic risk of revolution."
As this was a late addition to the text, I had not in fact discussed this alleged duty in a domestic context earlier in the book, although the section in Chapter IV on the undesirability of revolution is a natural precursor to it. To understand this persective, we have to think about cultures in terms of equilibria (or quasi-equilibria): every society consists of a mix of permitted behaviourial strategies. Cultural variants that stray too far from this adaptive equilibrium will be removed by natural selection, in the same way as a genetic mutation that confers no biological advanatage will be selected out of a species. As social environments (given by economic development, population and natural constraints) change, cultures change too - in much the same way that selection permits a species to adapt to natural environments.
Variation is allowed by this view of life and culture: in fact it is required to explain why cultures change and adapt over time. But structural forces act as selectors, reducing the frequency of maladaptive behaviour and encouraging the spread of adaptive innovations. In political and economic terms, ideologies and policies that increase the general welfare are more likely to spread and be widely employed than policies that are rigid, unstable or destructive. Of course, we have no way of knowing in advance whether a policy idea that we favour is adaptive or maladaptive: we can only try them out and see if evolution favours then. So far, so good.
Three Duties
Evolution is blind. Species and cultures both can go extinct if their environment changes faster than they can adapt, or if their behaviour sets are too inflexible, or if destructive mutations spread through their population unchecked. Cultural evolution is a marvellous system for generating social and economic progress: it has made humanity the dominant species at a planetary scale. Democracy, which permits and channels this variation with astonishing flexibillity and resilience, is the best system yet devised to harness this process for the common good. But there is no guarantee that cultural evolution will continue indefinitely: it's a minor miracle (only truly cosmic time scales) that our species possesses this capability at all, and a historical accident that we've evolved a political belief system suited to managing it.
Given the existence of human agency, however, I argue that cultural evolution imposes three ethical duties on individual behaviour. These ethical duties necessarily limit the range of legitimate political action and belief; nevertheless, they ensure that human societies remains dynamic and adaptive. Moreover, these duties override whatever cultural considerations have evolved in particular contexts and are ontologically prior to particular philosophical systems. In other words, they impose duties on individuals regardless of their own or their culture's belief system. These are not 'conservative' duties to respect existing institutions: they are duties which ensure that the evolution of cultural institutions is possible at all. These duties arise from the requirement that 'creative destruction' occurs in the context of a physical and cultural ecosystem which is sustainable. In that sense, they could be considered intergenerational duties, or measures to counteract short-term time discounting of political payoffs.
1) Firstly, individuals have a duty to pursue political and economic change only in those ways which guarantees the ongoing viability of the social environment for future generations. If one were so inclined, one could read into this duties to utilise the natural environment sustainably. I'm more of a humanist than an environmentalist, however, so for me this means that the pursuit of change must occur through actions which preserve the ongoing fabric of democratic society. In other words, even if we were in a position to do so, political actors must not undermine democratic norms and institutions, and must not seek to divide or separate themselves from the rest of society in the pursuit of their preferred political goals. Sorry kids, but revolution is out (regardless of its consequences), and so is dictatorship and separatism. Social systems must allow for the peaceful transfer of power between competing value sets.
2) Secondly, individuals have a duty to defend liberal democratic society against other actors that would seek to undermine or overthrow it. Guess what? Some actors are always going to cheat on their ethical duties for selfish advantage. Social cancers like fascism must be fought by society's 'immune system', or they will grow and consume the social organism until it dies. In game-theoretic terms, cooperative social behaviour is sustained by the potential punishment of deviance. Not everyone has to be a punisher, but enough people have to be willing to bear the costs of doing so in order to maintain equilibrium. This also applies internationally: the left cannot sit idly by while authoritarians states rip up international norms and must be willing to use coercion to ostracise and punish deviance.
3) Finally: in the event that a cohesive democratic society is destroyed, split or ceases to exist, individuals have a duty to fight to restore democratic society. Say there's been a revolution or civil war in your country, and a cohesive society has ceased to exist. Does victory (or partial victory) in that conflict mean that one is entitled to impose permanent decision-dominance over the parts of society one controls? Of course not. Revolt by one class over another, or conquest by one ethnic group over another, does not permit the extermination of the culture of the defeated. Autocracies can survive for a time of course - the Soviet Union was famously successful in rapidly industrialising and defeating Nazi Germany (at tremendous cost). But they are far less likely to be able to adapt to changing social and environmental circumstances, and will fall in time to societies that are more flexible. Only by restoring democracy as rapidly as possible can we ensure that ongoing viability of a society.