Final answer:
Jeremy Bentham argued that both legal rights and Natural Rights are fictions, stating that rights emerge only with the creation of civil society and government.
Step-by-step explanation:
The philosopher who argued that both legal rights and Natural Rights are fictions was Jeremy Bentham. Bentham, an English lawyer and philosopher known for his advocacy of utilitarianism, posited that rights are a creation of the state and do not inherently exist outside of societal structures. While philosophers such as John Locke, Voltaire, and Rousseau supported the idea of inalienable natural rights, Bentham argued that such concepts are nonsensical and that clinging to such notions only leads to chaos and unpredictability in society.