James Pethokoukis argues that markets are more robustly competitive than antitrust enthusiasts believe them to be . (I go ever further than does Pethokoukis . A close study of economic history turns up little, if any, evidence that markets have ever generated firm or industry sizes, structures, or practices that have harmed consumers over any significant-enough length of time. Indeed, reflecting on the government’s willingness to impose restrictions on both international and domestic trade – see the link just above to George Leef’s article – it’s preposterous to look to government, which habitually creates genuine monopoly power, for protection from imagined monopoly power.)
Scott Sumner writes about consumer and producer surplus  – and, especially you economists, be sure also to read carefully Pierre Lemieux’s comment  on Scott’s post.