During Bentham's lifetime, revolutions occurred in the American colonies and in France, producing the Bill of Rights and the Déclaration des Droits de l'Homme (Declaration of the Rights of Man), both of which were based on liberty, equality, and self-determination. Karl Marx and Friedrich Engels published The Communist Manifesto in 1848. Revolutionary movements broke out that year in France, Italy, Austria, Poland, and elsewhere. In addition, the Industrial Revolution transformed Great Britain and eventually the rest of Europe from an agrarian (farm-based) society into an industrial one, in which steam and coal increased manufacturing production dramatically, changing the nature of work, property ownership, and family. This period also included advances in chemistry, astronomy, navigation, human anatomy, and immunology, among other sciences.
Given this historical context, it is understandable that Bentham used reason and science to explain human behaviour. His ethical system was an attempt to quantify happiness and the good so they would meet the conditions of the scientific method. Ethics had to be empirical, quantifiable, verifiable, and reproducible across time and space. Just as science was beginning to understand the workings of cause and effect in the body, so ethics would explain the causal relationships of the mind. Bentham rejected religious authority and wrote a rebuttal to the Declaration of Independence in which he railed against natural rights as “rhetorical nonsense, nonsense upon stilts." Instead, the fundamental unit of human action for him was utility-solid, certain, and factual.
What is utility? Bentham's fundamental axiom, which underlies utilitarianism, was that all social morals and government legislation should aim for producing the greatest happiness for the greatest number of people. Utilitarianism, therefore, emphasizes the consequences or ultimate purpose of an act rather than the character of the actor, the actor's motivation, or the particular circumstances surrounding the act. It has these characteristics: (1) universality, because it applies to all acts of human behaviour, even those that appear to be done from altruistic motives; (2) objectivity, meaning it operates beyond individual thought, desire, and perspective; (3) rationality, because it is not based in metaphysics or theology; and (4) quantifiability in its reliance on utility. (353 words)
(Extracted from Michael Quinn, “Jeremy Bentham, “The Psychology of Economic Man,' and Behavioural Economics,” Oeconomia 6, no. 1 (2016): 3–32)

According to the text, what did Bentham consider the fundamental unit of human action, replacing concepts like natural rights?

During Bentham's lifetime, revolutions occurred in the American colonies and in France, producing the Bill of Rights and the Déclaration des Droits de l'Homme (Declaration of the Rights of Man), both of which were based on liberty, equality, and self-determination. Karl Marx and Friedrich Engels published The Communist Manifesto in 1848. Revolutionary movements broke out that year in France, Italy, Austria, Poland, and elsewhere. In addition, the Industrial Revolution transformed Great Britain and eventually the rest of Europe from an agrarian (farm-based) society into an industrial one, in which steam and coal increased manufacturing production dramatically, changing the nature of work, property ownership, and family. This period also included advances in chemistry, astronomy, navigation, human anatomy, and immunology, among other sciences.
Given this historical context, it is understandable that Bentham used reason and science to explain human behaviour. His ethical system was an attempt to quantify happiness and the good so they would meet the conditions of the scientific method. Ethics had to be empirical, quantifiable, verifiable, and reproducible across time and space. Just as science was beginning to understand the workings of cause and effect in the body, so ethics would explain the causal relationships of the mind. Bentham rejected religious authority and wrote a rebuttal to the Declaration of Independence in which he railed against natural rights as “rhetorical nonsense, nonsense upon stilts." Instead, the fundamental unit of human action for him was utility-solid, certain, and factual.
What is utility? Bentham's fundamental axiom, which underlies utilitarianism, was that all social morals and government legislation should aim for producing the greatest happiness for the greatest number of people. Utilitarianism, therefore, emphasizes the consequences or ultimate purpose of an act rather than the character of the actor, the actor's motivation, or the particular circumstances surrounding the act. It has these characteristics: (1) universality, because it applies to all acts of human behaviour, even those that appear to be done from altruistic motives; (2) objectivity, meaning it operates beyond individual thought, desire, and perspective; (3) rationality, because it is not based in metaphysics or theology; and (4) quantifiability in its reliance on utility. (353 words)
(Extracted from Michael Quinn, “Jeremy Bentham, “The Psychology of Economic Man,' and Behavioural Economics,” Oeconomia 6, no. 1 (2016): 3–32)

Which of the following is identified as Bentham's fundamental axiom underlying utilitarianism?