As outlined by Sam, "Patrick argues that the age of the all-encompassing multilateral deal is over". According to Stewart Patrick's very long Foreign Affairs article, major powers are recognising "the futility of negotiating comprehensive international agreements among 193 UN member states, in the full glare of the media and alongside tens of thousands of activists, interest groups, and hangers-on."
While Patrick’s piece might be thoughtful as a whole, this particular conclusion is simply wrong.
Anybody who has been participating actively, in whatever capacity, in any multilateral negotiation knows that such meetings run on two levels. Much like in a theatrical production, there is the authors text — here the text of an agreement to be negotiated — and then there is the particular staging of the show. In a multilateral negotiation the latter is the negotiation process, the way and means agreement is reached on the text (or not).
Both parts are indispensable if agreement, let alone the actual execution of what has been agreed, is to be reached. The very point of the UN and the whole UN system is its all encompassing nature. All states are equal but of course some are a bit more equal. The big majority of all countries who are little bit less equal rely for their international survival on their moments on the global stage which only the UN system can offer them. The staging of their particular moment, "in full glare of the media", and often assisted by "hangers -on" (in reality all kinds of NGOs who provide research and advice many countries would otherwise have no access to) is all important for them and their best way to try to influence the actual text being discussed.
Patrick is of course right to state that some international issues, such as climate and environment, have become too complex to be negotiated in one go and by a full plenary. Complex issues can and should be broken down in their components for more effective negotiation and/or be tackled only by those directly affected, but this does not mean that such plenaries have become obsolete.
Quite to the contrary: precisely because ever more complex international issues have to be negotiated internationally, it is imperative that all nations at one time or the other have the possibility to sound off on the large stage, also and especially for their home audience, on any issue. The only thing worse than including them in multilateral decision making would be to make them feel excluded. They would lose interest and turn to sabotaging international agreements. Also, it is often smaller countries, keenly aware that international leverage is their best defense and that they better not abuse this instrument, who will propose reasonable solutions, rather than the powerful countries used to getting their bilateral way.
Most bad things said about the UN system are true. It is often slow, unwieldy, irrational and unjust. Yet it is the only way the global community of almost 200 independent states, evermore linked on our flat world, can be assembled and induced to cooperate. Sustainable global governance needs both: international leadership by individual countries who can (and should) provide it as well as willing cooperation by all.