Solidarism is a strand of English School international relations theory associated most prominently with Nicholas Wheeler, Andrew Linklater, and (in earlier form) Hedley Bull's later work. It argues that international society is capable of agreeing not only on minimal rules of coexistence — sovereignty, non-intervention, diplomacy, pacta sunt servanda — but also on substantive cosmopolitan values, especially the protection of individuals from mass atrocity.
Solidarism is typically contrasted with pluralism, the position (developed by Bull in The Anarchical Society, 1977, and by Robert Jackson) that order between culturally diverse states depends on respecting sovereign equality and refraining from imposing particular conceptions of justice. Pluralists treat humanitarian intervention with suspicion; solidarists see it, under defined conditions, as a legitimate enforcement of shared standards.
Core solidarist claims include:
- States are not the only moral referents; individuals carry rights that the society of states should defend.
- Customary and treaty law — the Genocide Convention (1948), the human rights covenants of 1966, and the Responsibility to Protect doctrine endorsed at the 2005 UN World Summit — evidence a thickening normative consensus.
- Legitimate intervention requires criteria such as just cause, right intention, last resort, and reasonable prospects, drawing on just war traditions.
Wheeler's Saving Strangers (2000) is the canonical solidarist analysis, examining cases from Tanzania's 1979 ouster of Idi Amin to NATO's 1999 Kosovo campaign. Critics — both pluralist and realist — argue solidarism risks legitimising great-power discretion, eroding sovereignty selectively, and projecting Western liberal values as universal. Debates after the 2011 Libya intervention authorised by UNSC Resolution 1973 sharpened these concerns, with Russia and China subsequently citing perceived NATO overreach to block solidarist action on Syria.
Solidarism is therefore best understood not as a fixed policy programme but as a claim about the moral direction of travel of international society.
Example
Solidarist scholars often point to NATO's 1999 Kosovo intervention, conducted without UN Security Council authorisation, as evidence that international society was willing to act on shared humanitarian norms even against state consent.
Frequently asked questions
Cosmopolitanism locates moral standing in individuals and is sceptical of the states-system itself; solidarism works within the society of states, arguing that states can collectively agree on and enforce humanitarian standards.
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