Used rhetorically, it implies a forced choice:
"Either you're part of the solution or you're part of the problem."This may lead to a false dilemma or false dichotomy, where the choice doesn't actually matter, in the manner of Morton's Fork. John Morton, Lord Chancellor of Henry VII of England justified the taxation of England's nobility by saying:
-- Eldridge Cleaver, presidential campaign 1968.
"Either the nobles of this country appear wealthy, in which case they can be taxed for good; or they appear poor, in which case they are living frugally and must have immense savings, which can be taxed for good."This left the nobility in a position where either way, they would lose out. In formal logic, this is the definition of a dilemma as either option implies the same outcome, regardless of the individual truths of each option. This is also typified by characters who display black-and-white thinking, where people and situations are either good or evil, without ambiguity.
An ethical dilemma (or ethical paradox) occurs when someone is forced to choose between violating a moral code in order to survive. This is often used to refute or reinforce a moral code using a choice with one option weighted towards a more vital level of Maslow's hierarchy of needs e.g. Valjean's stealing in Les Miserables is justified by his need to feed his family.
Examples include Carneades' Plank (where two sailors swimming need the same plank to live, if one pushes the other away from it and causes them to drown, has the survivor commited murder?) and the Samaritan's dilemma that posits the presence of charity or state-sponsored aid will promote dependency as well as slothful or negligent citizens because the safety net will always be there since the choice between self-improvement through survival or just survival will always be weighted towards survival first.
A moral dilemma generally implies that doing the right thing may lead to a bad consequence while doing the wrong thing may lead to a better outcome. Machiavelli uses this in The Prince to justify the necessary evils that he believes a ruler must take as when all other issues are set aside, it is preferred on a practical level to have all things turn out well. Such consequences-based thinking is justified as follows.
In all men's acts, and in those of princes most especially, it is the result that renders the verdict when there is no court of appeal.In other words, the ends justify the means. What happens in a situation where either option is unacceptable (e.g. Sophie's Choice) or where the means are patently wrong is complicated by social relationships, spiritual tenets, political and economic factors and may lead to conflict between the audience and the story's point of view which may be driven by a conflict between social, moral or even spiritual values (one example is the shifting attitude to slavery). Where a moral dilemma comes into play, it must follow that there is a defined moral or ethical code potentially being violated.
Duty of commission (doing something) may lead to further complication based on the ability of the individual and the opportunity of the situation, for example is someone who can't swim expected to save someone from drowning in a riptide by jumping from a high cliff to get them? It also has no direct consequence on the individual beyond the individual's conscience or opinion of any witnesses to the scene (if the individual passes by, a coroner will likely rule accidental drowning) - highlighting the moral ambivalence sometimes found in matters of law since ability and opportunity are subjective and matters of judgement.
Duty of omission (not doing something) is a simpler moral imperative to understand (thou shalt not kill) as it's violation leads to evidence (a body) and direct consequences on the individual. All that remains is for the evidence and the relevant laws to be interpreted correctly for justice to be done - itself easier said than done.
There are instances where a dilemma may be dependent on other choices made by other characters such as the prisoner's dilemma, a component of game theory and driver behind mathematical arguments linked to the atomic bomb and the digital computer. Expanding this dilemma presents options where co-operation can further a plot or situation while developing tensions between individual agendas. The outcome and benefits of co-operation need to be signposted to prevent the nascent alliance from falling apart.
In all cases, the dilemma must be relevant to the character. Throwing someone into a situation where there are conflicts with values and morality may be a good way to build tension but needs context to the character and to the larger themes of the story. The ending of Romeo & Juliet would not be so poignant without reference to the love each feels that they cannot bear to live without each other and the backdrop of conflict between their families.