Utilitarianism is a teleological and consequentialist ethical theory that judges the morality of actions by their outcomes rather than their intentions or inherent nature. Its guiding principle is the principle of utility, which holds that an action is morally right if it produces the greatest happiness for the greatest number. The theory was first developed by Jeremy Bentham, who understood happiness in quantitative terms as pleasure and the absence of pain, and later refined by John Stuart Mill, who distinguished between higher and lower pleasures. Utilitarianism exists in different forms, most notably Act Utilitarianism, which assesses individual actions case by case, and Rule Utilitarianism, which follows general rules that tend to maximise overall happiness. Because utilitarianism is flexible, non-religious and outcome-focused, it is often seen as attractive in debates about sexual ethics. However, utilitarianism does not provide the best approach to sexual ethics, because it relies on unreliable predictions, subjective assessments of pleasure, and can justify abuse and serious injustice.

One significant reason why utilitarianism is not the best approach to sexual ethics is the problem of prediction and the subjectivity involved in estimating pleasure and pain. Bentham’s hedonic calculus attempts to measure pleasure using factors such as intensity, duration and extent, but in practice these factors are extremely difficult to apply to real sexual relationships. Sexual decisions often involve long-term emotional consequences that cannot be accurately predicted at the time. Peter Singer identifies the problem of prediction as the most serious difficulty with utilitarianism and the reason why he has moved further and further towards strong-rule utilitarianism and away from act utilitarianism over time. Furthermore, Bernard Williams argues that utilitarianism fails to take personal integrity seriously, reducing deeply personal decisions to impersonal calculations. In sexual ethics, where emotions, vulnerability and power dynamics are central, this reduction is particularly problematic. Pleasure itself is highly subjective, and what appears pleasurable may later be experienced as harmful or exploitative. This shows that utilitarianism lacks the precision and sensitivity required for ethical sexual decision-making, weakening its claim to be the best approach.

A further weakness is that utilitarianism risks legitimising sexual abuse and exploitation, particularly where the happiness of many outweighs the suffering of a few. John Rawls famously criticised utilitarianism for permitting injustice if it maximises overall happiness, arguing that it fails to respect individuals as separate moral persons. In sexual ethics, this is a serious flaw. Practices such as exploitative pornography, prostitution or coercive relationships could be justified if they produce pleasure for a large number of people, despite causing significant harm to a minority. Feminist scholars such as Catharine MacKinnon argue that focusing on pleasure alone ignores structural power imbalances, particularly between men and women, and normalises sexual harm. Utilitarianism lacks a clear mechanism to protect vulnerable individuals from being sacrificed for collective enjoyment. As a result, it fails to uphold key ethical values such as dignity, autonomy and justice, all of which are essential in sexual ethics.

An even more serious criticism is the problem of mob-rule, where act utilitarianism could justify morally abhorrent acts if they maximise overall pleasure. In theory, acts such as gang rape or child prostitution could be deemed morally acceptable if the pleasure of the majority outweighed the suffering of the victim. While utilitarians such as J.S. Mill hoped that higher pleasures and long-term consequences would prevent such outcomes, critics argue that this is not guaranteed by the theory itself. James Rachels points out that act utilitarianism has no absolute moral boundaries, meaning that nothing is inherently wrong. In sexual ethics, this is unacceptable, as certain acts—especially those involving coercion or lack of consent—are widely regarded as absolutely wrong regardless of consequences. A moral theory that cannot clearly and consistently condemn such actions cannot plausibly be considered the best approach to sexual ethics.

However, a strong counterclaim is that absolutist ethical theories are incompatible with modern, multicultural societies. Postmodern thinkers such as Jean-François Lyotard argue that there are no universal moral “metanarratives,” and many people adopt relativist views about sexual morality. From this perspective, utilitarianism appears more suitable because it avoids rigid rules and allows individuals and societies to weigh harm and benefit in context. Supporters may argue that traditional sexual absolutes fail to reflect diverse sexual identities, relationships and cultural values, whereas utilitarianism is flexible and inclusive. Despite this, there are some moral principles in sexual ethics that command near-universal agreement, even within pluralistic societies. One such principle is the absolute wrongness of sexual abuse, particularly in cases lacking informed consent. Philosophers such as Alan Wertheimer emphasise that exploitation occurs when one party takes unfair advantage of another’s vulnerability, regardless of overall pleasure produced. Consent functions as a moral threshold rather than a variable to be weighed. Utilitarianism treats consent as one factor among many, whereas many ethical frameworks see it as non-negotiable. This suggests that some absolute principles are not only compatible with modern society but essential to protecting the vulnerable. Therefore, the relativist objection does not successfully defend utilitarianism as the best approach to sexual ethics.

In conclusion, utilitarianism does not provide the best approach to sexual ethics. The strongest reason for this is that it can justify exploitation and abuse by prioritising overall pleasure over individual rights, dignity and consent. Its reliance on subjective calculations and its vulnerability to mob-rule make it ethically dangerous in such a sensitive area. While utilitarianism has value in encouraging consideration of harm and wellbeing, it must be limited by firm moral boundaries. Rule utilitarianism offers greater protection than act utilitarianism, but even this is insufficient without absolute commitments to consent and the intrinsic worth of persons. Ultimately, sexual ethics should be grounded not in calculations of pleasure, but in respect, justice and the protection of the vulnerable—principles that utilitarianism alone cannot adequately secure.