The starting-point: What drives evolution?
Evolution can be an enlightening concept to apply to arms control, provided that evolution itself is correctly understood. It is not synonymous with progress and improvement, nor is it necessarily uni-directional. It focuses on how organisms adapt to their physical and temporal circumstances: so the 'survival of the fittest' does not mean the triumph of the objectively 'best' or most advanced, but rather of those whose adaptation is most successful. Furthermore, in the modern understanding the process of evolution is not smooth and continuous. It has been called a 'punctuated equilibrium'  where things may stay the same for a long time before facing a sudden, rapid change, which might lead either to progress or to regression.
The way that arms control is understood and pursued, its relative standing, and its relative success have similarly varied over time. Arms control both in Europe and worldwide has been through numerous crises and changes of direction, and many would say that its progress has stalled or even been reversed at times. At its simplest, evolution in this field seems to be responsive to two sets of forces in the environment: the economics of fear and the economics of economics. What matters most about fear is not its origin or extent but how one-sided it is. If we feel unlimited apprehension about an enemy and/or define our opponents as inherently evil, no level of defensive capability can be enough to satisfy us and any arms restraint will be assumed only to help the 'bad guys'. If however we are aware that our own arsenals may also contribute to arms races and triggering conflict; if we would prefer to avoid the responsibility for killing and wounding and rather pursue our interests by non-violent means; and above all if we have historical reason for self-mistrust and fear of our own instincts, then we will be more inclined to seek safety at lower and balanced levels of capacity.
The economics of economics is even simpler. Arms and armies cost money, and while we need them to defend the other things we hold dear (territory, population, resources and welfare), very few countries have been prepared to spend so much on defence that their civil economy stops functioning and their people start to starve. But there are also some reasons for producing and owning weapons that have less direct links to survival. Some motives are related to status, prestige and display, both within and beyond the country. Others are linked to the productive economy: the value of arms factories for employment and for regional development, or the profitability of defence sales. Armed forces can also be used to train young citizens and create a sense of national unity, or to assist in law and order and civilian tasks like natural disaster response. These motivations for maintaining a certain level of capacity mitigate the 'economics of economics' logic, and may make countries reluctant to go too far in cuts or restraints even when the 'fear' factors are well balanced. Arms control thinking has arguably not done enough to address these complications; but at least, such factors tend to be less directly linked with risks of conflict.
If the elements line up to make arms restraint – unilateral, bilateral or multilateral – prima facie possible, a host of alternative ways exist to pursue it. Most of them have been tried out at least in some context and to some degree over the last century, and - at least for this author - there is no obvious reason to consider any one 'superior' to any other. The most extreme and comprehensive are the physical interdiction and destruction of (somebody else's) weapons, and the complete prohibition of classes of weaponry, as seen recently with chemical and biological weapons and various weapons/techniques viewed as 'causing unnecessary harm and having indiscrimate effects' . At the other end of the spectrum is self-control and voluntary avoidance, which may be prompted both by economic constraints and moral preferences, and includes help given by countries to others to destroy their weapons voluntarily . In between these extremes, control methods can intervene at every stage of the arms cycle, starting with controls and limitations on production, on ownership, and on trade and transfer. These last may take the form of export and technology transfer regimes, but also of physical checks and confiscation. When it comes to the employment of weapons in a military context, there may be limits or conditions placed on where and how the items are used (eg de-militarized zones, confidence building measures constraining military movements and activities, transparency and data exchange stipulations); or there may be actual limitations placed on numbers – freezes, ceilings, or cuts – possibly accompanied by verification.
Viewed in the light of evolutionary theory, whether all these options or only some of them should be labelled as 'arms control' – or, where to draw the line between 'arms control' and 'disarmament' – is not an interesting issue. Rather, the question should be what works or is most likely to work in promoting the aims in view for any given attempt at arms restraint: and the answer will often be some combination of approaches. Indeed, the complex interdependencies between the various methods deserve more thought than they have often been given. Just as one example, there are problems in ordering a poor country to give up a certain weapon when it relies economically on selling that weapon, believes that weapon is the only thing holding its border safe against a troop concentration on the other side, and cannot afford to safely destroy its stocks.
From a 20th to a 21st century environment
The late 20th century is rightly seen as the most productive historical period ever in arms control. Its successes, however, depended on making a shrewd selection from the spectrum of measures just outlined to address a given set of problems – also carefully selected for their urgency and manageability – that typified the age. Its architects proceeded from a number of hypotheses and principles that, by and large, correctly reflected the prevailing realities. In particular and as this author has argued at more length elsewhere , they could assume a broad balance of military capabilities, of deterrent doctrines, and of what are here called 'fears' between the two armed camps of the Euro-Atlantic region. They were addressing themselves to risks of war between states, rather than to internal conflicts or the 'wars of liberation' that took place in many former European colonies in Africa and Asia. (This is not to say that the latter were neglected but they were not associated with arms control measures, except weapons collection after some of the civil wars.) They worked also to secure universal bans on 'inhumane' items such as chemical weapons, incendiaries and booby-traps, confident in the assumption that all human beings would share an abhorrence towards these on the basis of common experience or knowledge. Finally, they saw the method of negotiating legally binding treaties and conventions, whether open for universal participation or in regional settings like the Conventional Forces in Europe (CFE) agreements , as the ‘classic’ and most powerful instrument available both for actual disarmament and for defining other forms of restraint.
Underpinning or flowing from these preferences were other less explicit assumptions, starting with the belief that states were the (only) relevant actors and were equally competent to make and implement such agreements. Thus with some exceptions like the establishment of the Organisation for the Prohibition of Chemical Weapons  to service the Chemical Weapons Convention, implementation of commitments was seen as a national business and enforcement depended on the vigilance of the community of other signatories. Further, the initiative for action aiming at actual disarmament (other than for 'inhumane' weapons), for non-proliferation measures and for export controls came overwhelmingly from the Euro-Atlantic zone. It had a double logic there since it not only reduced war risks in Europe, but lowered the temperature in the East-West strategic rivalry exported by the two blocs to most of the rest of the world.
Since the Warsaw Pact and Soviet Union broke up at the end of the 1990s and as the world moved into the 21st century, these features of the 'classic' arms control environment have changed quite dramatically, more than once. The obvious differences started with the loss of true strategic balance between East and West, even if the Russian Federation maintained an approximate nuclear parity with the USA. Not only was the USA left with by far the world's single greatest conventional forces and military-technical capacity, but its notions of national security and the strategic use of military means shifted progressively away from the European focus and from the preservation of an East-West status quo through deterrence. Its posture became a more active, truly global one of transformative intervention (Former Yugoslavia, Gulf War), retaliation, and – under President George W. Bush – even forceful 'pre-emption' . Russia's posture, at the same time, became less global through the loss of former Soviet territories and overseas bases, and hence more exclusively territorial and defensive. China also has been focussed on its own territory and neighbourhood up to the very recent past, and has not made active war against anyone since Vietnam in 1979. More even than asymmetry in numbers, this asymmetry in doctrines and strategic visions makes negotiations for mutual restraint particularly difficult even in regions where the powers concerned are simultaneously present. To take only the most obvious example, the USA has motivated its missile defence plans in and around Europe as a shield against possible Middle Eastern nuclear proliferation, while to Russia any such installations near its borders mean a further extension of US military influence and a flaunting of Western strategic superiority in its own backyard .
Broader changes have included the general shifting of the world system towards multi-polarity, with other regions no longer divided between the adherents of East and West, leaving more scope both for autonomous regional conflicts (especially intra-state ones) and for emergent regional power bases. Matching this greater strategic complexity is a greater, and still continuing, diffusion of military power and associated technological knowledge. Over and above the post-9/11 recognition of terrorism as an 'asymmetric' threat, cyber-technology has emerged as a weapon that an otherwise weak state or even an individual can wield with effect against even the most powerful adversary.
The proliferation of such multi-use, potentially subversive techniques, unconventional means of attack, and the worldwide smuggling of small arms and light weapons (SALW) at the other end of the technological spectrum, have both helped to drive a major shift in strategic thinking – led by but not confined to the West – towards the challenges presented by non-state actors . Whether these be parties to a civil war, terrorist movements, violent criminals, shady businesses or cyber-'hackers', their negative roles in security processes not only threaten the general monopoly of force by nation-states, but are also intimately linked with the circulation, use, design and even the production of weaponry including weapons of mass destruction. Yet the 'classic' Treaty method of defining arms restraints and the classic, state-led method of implementing them are almost completely unsuited to handling such actors. The latter have neither the legal personality to make international agreements, nor the executive competence, in many cases, to control their own assets and adherents . National and international laws that define obligations for governments and for traditional actors like armed forces are anyway ill-designed to 'capture' and regulate the actions of such players, especially when working in the new transnational, globalized space or indeed in a virtual environment. Not only weak governments in conflict countries, but the world's strongest states and organizations have been struggling with these conundrums for more than two decades now.
Arms restraint: A new mix of tools?
The pattern of endeavours for arms restraint has not unnaturally evolved as a result, driven by conscious choices but also by some less carefully examined assumptions. Few efforts are made today at continent-wide restraints, and in the implementation of the East-West CFE Treaty there has been actual regression . Instead, measures are typically designed either at global level to involve all poles of power and all possible transnational dissemination routes; or in an individual country (possibly plus immediate neighbours) during conflict or as part of peace-building thereafter . Even more significantly or at least, more controversially, the method of promoting restraint has shifted away from the centrality of treaty processes. The US Administration of George W Bush was exceptionally forthright in seeing treaties (and other forms of negotiated, law-based institutional action) as hampering the good guys more than they restrained the bad guys; but it would be unfair to give the USA sole responsibility for the shift or to see it reflected only – as in the invasions of Iraq and Afghanistan – in coercive military action. Large numbers of Western and other states, including not infrequently the other great powers, have joined in actions to 'coercively' block supplies to maverick states and violent non-state actors by methods ranging from formal embargoes, sanctions and regulations  negotiated at the UN, to tighter safety standards at places of production (including new nuclear safeguards), wider participation in export control regimes , improved controls on cargoes by air and sea, monitoring of shipping (the Proliferation Safety Initiative ), and more.
All these examples could be argued to reflect adversarial, 'us' against 'them' thinking and to be inherently asymmetrical, in that the implementing countries have not been restrained in their own military capacities – or have even increased them for the new tasks. Some post-9/11initiatives, however, also had the effect of improving positive cooperation and sharing, not least between former adversaries. The Organization for Security and Cooperation in Europe (OSCE), for instance, has adopted common positions on non-proliferation and SALW control that unite EU and NATO member states with Russia and its adherents. The US, EU, Norway and Japan have worked to help Russia destroy its surplus and obsolete nuclear holdings and to close down or convert dangerous chemical production facilities. Regimes developed at the UN for universal application such as UN Security Council Resolution 1540 on WMD possession and transfer have included follow-up processes to help weaker or less informed states live up to their obligations. Sizeable funds have been dispensed by states and organizations on helping partners build new competences in weaponry and WMD control, including training for border and customs officials. Such solutions reflect the 'classic' conception of arms control by implying equal recognition, balanced obligations and the growth of trust; but they also belong within the more general post-Cold War trend of seeking security through active cooperation and intervention rather than restraint – a tendency also seen in the multiplication of 'peace missions' worldwide .
At the same time, the Treaty method has not in fact been extinguished but rather corralled into some more specific areas, and experimented with in some newer ones. The latest and largest experiment is the Arms Trade Treaty adopted in the UN General Assembly (itself an intriguing procedure) on 2 April 2013  but the UN SC Resolutions already alluded to on terrorist financing and WMD governance represent a distinct new form of universal, legally binding instrument . The process of finding new classes of 'inhumane' weapons to be universally banned has continued, most recently with the 2008 Convention on Cluster Munitions . It has, however, in the last two decades focussed largely on low-tech, 'poor men's' techniques that are less likely to be considered vital by advanced military nations, while avoiding topics linked with new-horizon technologies (with the honourable exception of the ban on using lasers for blinding)  and with equipment for use in internal security. The US and Russian Federation concluded a new START Treaty in 2010 and brought it into force in 2011, though the two nuclear superpowers remain divided over the need for controls on ballistic missile defence – where President Obama has chosen to continue the Strategic Defense Initiative albeit in a much reduced form . Last but not least, legally binding agreements made in the context of post-conflict peace settlements have sometime created arms control/reduction obligations for specific states or groups of states, though this method – highly successful in the 'Florence agreement' applied to Former Yugoslav nations after the Dayton Agreement  – has not been as widely experimented with as one might wish.
Should the friends of arms control today be trying to re-extend the Treaty method from this surviving foundation, to re-conquer the space taken up since the 1990s by other methods and other actors in arms restraint? To try to turn the clock back in an environment so drastically changed, and still changing, would go against general evolutionary logic. Further, when considered as just one part of an arms control toolbox it becomes clearer that formal international-legal instruments have their limitations as well as strengths. Not only are they harder to apply to non-state actors, but they take time to negotiate and once adopted, are hard to amend and adapt. They do not per se create cooperative communities of the kind that have brought most of the world's advances in peaceful coexistence: rather, they have often spurred blaming-matches over compliance that have exposed (if not actually aggravated) international tensions. The worst-behaving countries can simply decline to sign up, or find a way of withdrawing when the constraints become inconvenient as North Korea did with the NPT in 2003. Above all, such instruments are difficult to apply to tensions arising from doctrinal asymmetries, such as the uneasy coexistence in Europe between Russia's (and some of its Western neighbours') territorial concerns on the one hand, and intervention-oriented concepts that see the continent more as a launching pad, on the other.
The way ahead
What to do? To be 'fit' for survival in a Darwinian sense, arms control must constantly review its instruments and perhaps work harder on using them in conjunction. To survive in a multi-polar environment with widely diffused destructive capacities, it must similarly widen the ownership of – which is more than just participation in – all phases of weaponry restraint. This means assimilating more varied interests and cultures, but should not be impossible at a time when 'rising' states are creating more constituencies with a stake in a peaceful status quo. The latter is also true of the great majority of lawful non-state actors, whose understanding and expertise in their own fields should be better harnessed to deal with the maleficent minority. Two more specific thoughts: when discussing with transition or post-conflict governments how to reform their security sectors, topics of defence budgeting, procurement, and arms management including export control should be far more strongly and systematically integrated than they have been hitherto. And it would be worth considering whether a wider global buy-in could be assured for 'humanitarian' efforts by opening up the concept to address such topics as human rights in military service, anti-corruption in procurement, and stronger 'green' standards on weapons production, use, and disposal worldwide.
With such a wide range of possible options, arms control will only become obsolete and infertile if it allows itself to do so. Yet the short-term environment for its survival is not promising. To return to our starting points: the economics of economics after the global crash have prompted many defence cuts, but are also shifting balances between the worst-hit, and less-affected, players in a potentially destabilizing way. They encourage new export drives by hard-pressed defence producers, and increase the temptation to rely on relatively cheap nuclear weapons or perhaps new mass-destruction techniques. Nor is an early solution visible to the disrupted and dysfunctional economics of fear. While the US has a President inclined towards caution both in military investment and deployment, Russia continues striving to make up what it sees as a 20-year shortfall in defence production and force strength. The US policy 'pivot' towards Asia  merely highlights another, Asian-Pacific strategic complex that involves multiple powers in rapid evolution and includes few if any arms control traditions . Problems of balance and mutual comprehension in other regions like the Middle East and South Asia are getting no easier. None of this is made better by twelve years of relative international down-grading of arms control 'culture' and the imperatives of restraint since 9/11. Clearly, the supporters of these causes are going to have to tap new energies, and seek better synergy between their efforts in different fields, if arms control is to survive. They should also ponder the complex and sometimes unwelcome lessons of evolutionary history.
 A term coined by evolutionary biologists Niles Eldredge and Stephen Jay Gould in the early 1970s.
 The cited definition was used in the international treaty known for (short) as the Certain Conventional Weapons (CCW) convention of 1980. More broadly, humanitarian-motivated bans or limitations on military techniques and weaponry have evolved out of the 'Geneva Conventions' developed in 1864-1949, and now include Additional Protocols to those conventions as well as separate treaties on items such as anti-personnel mines.
 A modern example is the Global Partnership helping, mainly, Russia to destroy obsolete and surplus stocks of nuclear and chemical weapons. Programmes to collect and destroy small arms have also been sponsored i.a. by NATO and the Organization for Security and Cooperation in Europe (SOCE).
 Bailes, Alyson J.K. (2012),'The changing role of arms control in historical perspective', in Meier, Oliver & Daase, Christopher (eds.), Arms Control in the 21st Century, Routledge, London, pp. 15-38.
 This idea was developed in response to the terrorist attacks of '9/11' and is expounded in the US National Security Strategy of September 2002. Available at http://www.state.gov/documents/organization/63562.pdf.
 Lachowski, Zdzislaw (2007), ‘Foreign Military Bases in Eurasia’, SIPRI Policy Paper, no. 18. Available at http://books.sipri.org/product_info?c_product_id=339.
 See eg Bailes, Alyson J.K. (2012), 'The Strategic Object of War', in Lindley-French, Julian & Boyer, Yves (eds.), The Oxford Handbook of War, Oxford University Press, Oxford.
 A new and encouraging way of overcoming these particular problems has been developed by the NGO 'Geneva Call' in its work with non-state groups on honouring humanitarian restrictions; see www.genevacall.org.
 As a result of political disputes connected with Russian deployments in the South Caucasus, NATO states did not proceed to ratify the Adapted CFE Treaty of 1999, and in 2007 the Russian Federation stated it would cease implementing CFE commitments as from December that year.
 The reference is to arms trade embargoes imposed on specific destinations, and 'Disarmament, Demobilization and Reintegration' (DDR) programmes applied in post-conflict locations to dispose of illegal/surplus fighting units and their weapons.
 These include UN Security Council Resolutions 1373 and 1540 introducing worldwide restraints on terrorist financing, and unauthorized possession of/trade in WMD, respectively.
 Among multilateral export control groups with purely Western roots in the Cold War, the Nuclear Supplies Group and Zangger Committee now include both Russia and China (with totals of 47 and 38 members respectively) while the Wassenaar Arrangement on conventional arms exports (41 members) includes Russia and Ukraine. See also, Amitav, Mallik (2004), ‘Technology and Security in the 21st century: A demand-side perspective’, SIPRI Research Report, no. 20.
 Such missions, if civilian and mixed operations be included, have roughly doubled in two decades mainly as a result of other organizations besides the UN entering the field. Latest details in Dundon, Jane (2013), 'Global trends in peace operations', SIPRI Yearbook 2013: Armaments, Disarmament and International Security, Oxford University Press, Oxford.
 See http://www.un.org/disarmament/ATT/.
 As such they are also controversial, see Ahlström, Christer (2007) , 'Security Council Resolution 1540: Non-proliferation by means of international legislation', SIPRI Yearbook 2007. Available at <http://www.sipri.org/yearbook/2007/11/11A>.
 Lasers are covered in Protocol IV to the CCW (note 2 above), adopted by the UN in 1995. In another important technological sphere, a convention to Prevent an Arms Race in Outer Space (PAROS) has been on the Conference on Disarmament (CD) agenda at Geneva for many years but remains politically blocked.
 China and Russia do apply force restraints and confidence building measures on their mutual border.