At the pleading stage, general factual allegations of injury resulting from the defendant's conduct may suffice, for on a motion to dismiss we “presume that general allegations embrace those specific facts that are necessary to support the claim.” In response to a summary judgment motion, however, the plaintiff can no longer rest on such “mere allegations,” but must “set forth” by affidavit or other evidence “specific facts,” , which for purposes of the summary judgment motion will be taken to be true. And at the final stage, those facts (if controverted) must be “supported adequately by the evidence adduced at trial.”