Contributed by Jonathan Stevenson / There are a fair few viable organizing concepts for group art exhibitions. One particularly challenging one is to present viewers with a tour d’horizon of emotions and attitudes that seem to prevail at a given historical moment. The key to optimal execution, of course, is to avoid both the obvious and the obscure. In “Each Own” at Springs Projects, curators and gallery co-founders Cate Holt and Tommy White strike the right balance, strategically deploying the work of six exceptional…