There is no appeasing Donald Trump, or deterring him

Andrew Coyne/The Globe and Mail: It isn’t just that he has no understanding of policy, nor any knowledge of history to guide him; or that he conforms to none of the norms of custom, morality or law. It is that, even understood as a wholly self-involved, self-serving bundle of id, one whose only motive is self-aggrandizement and self-enrichment, Mr. Trump is incomprehensible. His actions make no sense even in terms of rational self-interest. It’s all just random impulses, fleeting grudges, synaptic burps, based on who spoke to him last, what he saw on TV or what he had for breakfast, for all I know…