I will mention the ad hominem fallacy first because it is one of the simplest and most popular. We’re all familiar with it, if not in theory then at least in practice. It means to argue against the person or ‘to the man’, and it involves trying to refute an argument by attacking the person who makes it rather than the argument itself.
In popular politics, ad hominem attacks are plentiful, made all the more frequent by the fact that popular politicians are such easy targets for ridicule. Donald Trump, to take a recent example, presented an easy target for outrage due to his antics. Yet, as disagreeable as his personality was to some, it has no bearing on the rightness or wrongness of his policy decisions. And yet policy decisions are complex and the analysis of outcomes takes work. Easier to simply replay an offensive joke made by Trump a hundred times over, and those predisposed to find him repulsive will reject even his most prudent decisions.
That is not to say that personal morality has no bearing on the question of suitability for leadership, but from a rational and even a historical standpoint, there is a distinction between the office and the one who holds it, and the presence of vice in the leader does not necessarily mean that he will not excel where it matters most. We are not arguing that Donald Trump is an example of this apparent contradiction, but some of America’s best presidents have been subject to vice.