Joseph S. Nye, Jr. uses a “three-dimensional scorecard” to monitor the performance of each US president – from FDR to Trump – looking at the “motives, means, and consequences” of his actions. Many Americans say “they want a moral foreign policy, but disagree on what that means,” because they are unsure of the criteria by which they judge a foreign policy. This methodology would show how these presidents’ moral views affected their foreign policies.

The author believes good moral reasoning should be three-dimensional, weighing and balancing intentions, consequences, and means. As the public always uses moral reasoning to judge foreign policy, values and “clearly stated objectives helped educate and motivate the public at home and abroad.” However, logic and facts may sometimes not be a useful weapon against emotion, when public sentiment is so powerful that it is insensitive to reasoning.

Ronald Reagan is being remembered for his part in ending the Cold War peaceably, thanks to the chemistry between him and Mikhail Gorbachev. The author says success of Reagan’s “moral leadership also relied on his means of bargaining and compromise,” but it was not always the case. Reagan's contradictions were also much on display in his conduct of foreign policy. He saw the world in terms of a stark contrast between good and evil.

Athough his vagaries were mostly checked by foreign policy wonks, the drift of policy during his first term was unambiguous. In the name of anti-communism, every dubious military regime in Latin America was propped up, while all leftist movements were opposed. His “initial rhetoric in his first term created a dangerous degree of tension and distrust between the United States and the Soviet Union, increasing the risk of a miscalculation or accident leading to war. But it also created incentives to bargain.”

According to the author, George H.W. Bush “did not promote a transformative foreign-policy vision at the end of the Cold War. His goal was to avoid disaster during a period of rapid and far-reaching geopolitical change.” He had the acumen to limit “his short-term aims in order to pursue long-term stability.” Thanks to his prudence in a “turbulent” time, he managed to “achieve American goals in a manner that was not unduly insular and did minimal damage to the interests of foreigners. He was careful not to humiliate Gorbachev and to manage Boris Yeltsin’s transition to leadership in Russia.”

Indeed, Bush could claim to have been one of the most successful foreign-policy presidents after World War II, steering the US and its allies successfully through the collapse of communism and coordinated support for the reunification of Germany. On his watch the US acquired hegemony, a position of unprecedented global dominance in a unipolar world. In 1990 his response to Saddam Hussein’s invasion of Kuwait was triumphant and had international backing, in marked contrast to his son’s invasion of Iraq, which was endorsed wholeheartedly by only a handful of governments.

It was widely assumed that George HW Bush was unenthusiastic about the rightwing tone of his son’s administration, but he remained discreet about it. Indeed, no one can tell what George W. Bush’s foreign polcy would have looked like without the 9/11 attacks. He surrounded himself with war hawks, who cemented the neoconservative ideology. They were the unapologetic cheerleaders of the 2003 Iraq war, which Bush himself once admitted as "a big mistake".

Republicans were the realists with a world view: “The world is a jungle, there are no norms, and the only thing that matters is that potential foes be balanced and contained." When the USSR existed, Republican realism appeared to have a real moral content, since it was about balancing and containing Communism.

In the post Cold War era, without the threat of a morally vile and strategically lethal enemy - the Soviet Union - the GOP had drifted toward a sort of know-nothing, embracing isolationalism. Since the 9/11 attacks, the Bush administration embarked on military forays in Iraq and Afghanistan fighting the “War on Terror.” The two adventures have cost over $5 trillion.

Somehow Donald Trump manages to make George W Bush look like a colossus of domestic policy and world affairs. He claims, unconvincingly, to have opposed the Iraq war. Yet his vice-president, Mike Pence – who was such an ardent supporter of that war that he claimed Saddam Hussein was linked to al-Qaeda.

Trump’s “America First” in foreign policy does not make and keep America great. He sees his leadership as that of a corporate business, and the international community has to pay the US for providing and securing the supply of global public goods. Moral compass and ethics are irrelevant, because the US has merely its national interests at heart.

The author insists that a “moral foreign policy not only makes Americans safer, but also makes the world a better place….. Even then, the nature of foreign policy – with its many contingencies and unforeseen events – means that we will often wind up with mixed verdicts.”

Most people base their moral judgements not on evidence or facts, but on emotions, that ebb and flow. Political leaders are eager to wield influence over how history judge them.