It has become common in recent days, in which the 2 leading candidates for the US Presidential election have achieved unfavourable poll ratings, to regard voting for either candidate as a vote for the "Lesser of Two Evils" (LEV). Tempting though it may be to vote for a candidate simply in the hope of excluding another, this is a questionable ethical policy with potential risks for democracy. The "Lesser of 2 Evils" principle (LEV) has a long history of application in US Foreign Policy in promoting intervention in wars to exclude a "worse evil". So ingrained has this aspect of Realpolitik become in the US political psyche that it has become axiomatic of US public polity in the conduct of government. It has recently been promoted as such by Noam Chomsky who, in an uncharacteristically weak argument, has exhorted the left in the US to vote for Hillary Clinton.
But Chomsky is wrong as is the political philosophy underpinning LEV which prevails as a result of its widespread acceptance in the US political Establishment and his argument exhibits many of the blind assumptions made concerning LEV. The principal area in which LEV is cited is in US Foreign Policy and a casual glance at its operation here gives a sense of the problems with it as an ethical system: Vietnam, , Afghanistan, Iraq and Libya have all been subjected to horrific bombing, invasion and military degradation by successive US governments on the basis that to do so represented the LEV. There are few today even in the US who, with the benefit of hindsight, would concur that in its application in the US Foreign Policy sphere LEV can be supported as a sound ethical principle. There are indeed, many outside of the US who would regard its support of LEV to be an evil in itself. Clearly, there are other motivations for US invasions other than LEV considerations - not least geopolitical motives - but the adherence to LEV has enabled successive US govts to conduct a programme of widespread military aggression which it would otherwise have had few means of justifying. It has come to be the primary means of justifying a brutality that is rampant in the US and which successive Presidents have subscribed to wholeheartedly with disastrous consequences for the world.
Certainly LEV is a persuasive argument to governments facing complex issues and situations both domestically and abroad, but it is fraught with difficulties. A clear example of a sound application of LEV could be considered to be with the institution of the police force: police forces restrain liberty for the benefit of all because without them there would be a degree of lawlessness not compatible with the functioning of civilised society: it may thus be said that police forces are the LEV: a loss of liberty (evil) is incurred to avoid lawlessness (greater evil). But that brings us to the crux of the matter: LEV seems to have a reasonable application where there are 2 options and not more. If we apply it to situations were there are more than 2 options then we run into difficulty. In the case of policing it is apparent that there is no third way - or at least no-one has yet found one. LEV can therefore be safely applied in this instance. Again, in the situation where a knife-wielding madman approaching a group of school children can be disabled by running him down in a vehicle, we see an appropriate application of LEV because there seems to be no third way - and thus a great evil may be avoided by opting for a lesser evil. Were it possible to prevent the knifeman by, say, shutting the school gates, then this would remove the act of running him down from the LEV principle, because there would be 3 possibilities. If a policeman with a taser device was observed approaching then we would be in possession of a number of options: we would then have a complex moral decision to which LEV would be an unhelpful and possibly harmful remedy. That is because we would be seeking to apply a simple response to a complex problem which would potentially be detrimental and may result in a poor moral choice being made. Scaling up to the case where a conflict between the US and another country arises, there are myriad options available and by virtue of this LEV is not a good moral principle to apply. The situation in any of the recent examples of countries attacked by the US in the past 50 years has never been an either/or situation. Indeed, such situations have been subject to widespread arguments and protests concerning other options. The fact that LEV has been used to justify war, bombing, intervention etc is a testament to its misapplication rather than its wrongness as a principle per se, but given the complexity of international relations it is probably safe to regard LEV as unlikely to be applicable to most issues.
There are also severe problems with LEV in its application in the public sphere aside from these practical considerations: