Plagued with doubt and uncertainty in sensory knowledge, Descartes is struck with the idea that everything he knows is false. He considers the possibility that he has been deceived by an 'evil demon' and is left with nothing to lean on, until he arrives at the phrase 'cogito ergo sum' ('I think, therefore I am'). Among the most quoted philosophical works in history, Meditations on First Philosophy and Discourse on the Method together display the full workings of Descartes' skeptical method and the formation of his famous phrase.

John Locke (1632-1704) was a product of his troubled times: he lived through the English Civil War, the Interregnum, the Restoration, Monmouth’s Rebellion, the Bloody Assizes and the Glorious Revolution. His empirical thinking was very much directed at finding rational solutions to the root causes of those troubles.

Often considered the foundation of political liberalism, John Locke's Two Treatises of Government was first published anonymously in 1689, in the wake of England's Glorious Revolution. In The First Treatise of Government, Locke refutes the idea of divine monarchy, while The Second Treatise of Government articulates Locke's philosophy of government, which he based upon his theories of natural rights and the social contract.

Immanuel Kant’s Critique of Pure Reason can lay claim to being the most important single work of modern philosophy, a work whose methodology, if not necessarily always its conclusions, has had a profound influence on almost all subsequent philosophical discourse. In this work Kant addresses, in a groundbreaking elucidation of the nature of reason, the age-old question of philosophy: “How do we know what we know?” and the limits of what it is that we can know with certainty.

The leviathan is the vast unity of the State. But how are unity, peace, and security to be attained? Hobbes’ answer is sovereignty, but the resurgence of interest today in Leviathan is due less to its answers than its methods: Hobbes sees politics as a science capable of the same axiomatic approach as geometry.

Published in 1748, An Enquiry Concerning Human Understanding is Scottish empiricist philosopher David Hume's distillation of his mature philosophy. Addressing themes including the limits of human understanding, the compatibility of free will with determinism, weaknesses in the foundations of religion, and the appeal of skepticism, An Enquiry Concerning Human Understanding is Hume's attempt to revise and clarify the ideas of his earlier A Treatise of Human Nature.

Perhaps one of the most revolutionary works of philosophy ever presented, The Phenomenology of Spirit is Hegel's 1807 work that is in numerous ways extraordinary. A myriad of topics are discussed, and explained in such a harmoniously complex way that the method has been termed Hegelian dialectic. Ultimately, the work as a whole is a remarkable study of the mind's growth from its direct awareness to scientific philosophy, proving to be a difficult yet highly influential and enduring work.

Inside this brilliant three-in-one book collection, you’ll uncover a wealth of philosophical insights about truth, faith, and the universe around us. Drawing on the arguments and musings of the famed philosopher, David Hume, this book reveals his ideas on the questions that define our very existence. Brought to life in this collection for a modern audience David Hume’s work has stood the test of time to resonate with people across the ages.

Schopenhauer was just 30 when his magnum opus, Die Welt als Wille und Vorstellung, a work of considerable learning and innovation of thought, first appeared in 1818.

Much to his chagrin and puzzlement (so convinced was he of its merits), it didn't have an immediate effect on European philosophy, views and culture. It was only decades later that it was recognised as one of the major intellectual landmarks of the 19th century.

From the moment of its publication in 1748, The Spirit of the Laws proved to be a controversial work provoking widespread interest. Within three years it had been translated into various European languages - and was swiftly added to the List of Prohibited Books by the Roman Catholic Church. It is a remarkable book, a potpourri of observations and comments ranging far and wide over the social activities of mankind and it exerted a great influence on political leaders in the following decades.

First published in 1710, George Berkeley's A Treatise Concerning the Principles of Human Knowledge is a seminal contribution to Empiricist philosophy. Making the bold assertion that the physical world consists only of ideas and thus does not exist outside the mind, this work establishes Berkeley as the founder of the immaterialist school of thought. A major influence on such later philosophers as David Hume and Immanuel Kant, Berkeley's ideas have played a role in such diverse fields as mathematics and metaphysics and continue to spark debate today.

This Leibniz collection contains some of the philosopher’s most important works and ideas, spans three decades and illuminates the fascinating intellectual journey undertaken by him in his quest for truth. A prodigious polymath, Leibniz was a mathematician, philosopher, physicist and statesman and engaged with a sweeping range of ideas and disciplines, striving throughout his life to be at the cutting edge of scientific thinking. These Principal Essays are arranged in chronological order.

Critique of Judgement was published in 1790 and is divided into two parts, the Critique of Aesthetic Judgement and the Critique of Teleological Judgement. Our ‘judgements of taste’, as Kant describes our aesthetic judgements, have both a personal and a universal function: personal, because we have a subjective aesthetic response to the ‘agreeable’, the ‘beautiful’, the ‘sublime’ and the ‘good’; but also there is a ‘universal’ aspect because our aesthetic response has a ’disinterested’ element. This brings under Kant’s spotlight, for example, the concept of beauty and the perception of beauty.

The Republic poses questions that endure: What is justice? What form of community fosters the best possible life for human beings? What is the nature and destiny of the soul? What form of education provides the best leaders for a good republic? What are the various forms of poetry and the other arts, and which ones should be fostered and which ones should be discouraged? How does knowing differ from believing?

In Three Dialogues (set in a ‘Platonic’ garden), Hylas begins by challenging Philonous that he denied the existence of material substance. ‘What!’ says Hylas. ‘Can anything be more fantastical, more repugnant to Common Sense, or a more manifest piece of Scepticism, than to believe there is no such thing as matter?’ And Berkeley, in the guise of Philonous, replies, ‘Softly, good Hylas. What if it should prove that you, who hold there is, are, by virtue of that opinion, a greater sceptic, and maintain more paradoxes and repugnances to common sense, than I who believe no such thing.’

John Locke (1632-1704) was a product of his troubled times: he lived through the English Civil War, the Interregnum, the Restoration, Monmouth’s Rebellion, the Bloody Assizes and the Glorious Revolution. His empirical thinking was very much directed at finding rational solutions to the root causes of those troubles.

Credited as the Father of Liberalism and revered for his ground-breaking theories, John Locke left behind a legacy which has radically shaped political and philosophical thought for over 300 years. His writings continue to inspire and educate people to this day, from founding our central ideas of consciousness and knowledge to creating a framework for society which greatly influenced America’s founding fathers.

Often considered the foundation of political liberalism, John Locke's Two Treatises of Government was first published anonymously in 1689, in the wake of England's Glorious Revolution. In The First Treatise of Government, Locke refutes the idea of divine monarchy, while The Second Treatise of Government articulates Locke's philosophy of government, which he based upon his theories of natural rights and the social contract.

Immanuel Kant’s Critique of Pure Reason can lay claim to being the most important single work of modern philosophy, a work whose methodology, if not necessarily always its conclusions, has had a profound influence on almost all subsequent philosophical discourse. In this work Kant addresses, in a groundbreaking elucidation of the nature of reason, the age-old question of philosophy: “How do we know what we know?” and the limits of what it is that we can know with certainty.

Aristotle’s Nicomachean Ethics and Eudemian Ethics represent, in many ways, the Western classical springboard for the systematic study and implementation of ethics, the optimum behaviour of the individual. (By contrast, Aristotle’s Politics concerns the optimum blueprint for the city-state.) It is in the hands of each individual, he argues in these books on personal ethics, to develop a character which bases a life on virtue, with positive but moderate habits.

This Leibniz collection contains some of the philosopher’s most important works and ideas, spans three decades and illuminates the fascinating intellectual journey undertaken by him in his quest for truth. A prodigious polymath, Leibniz was a mathematician, philosopher, physicist and statesman and engaged with a sweeping range of ideas and disciplines, striving throughout his life to be at the cutting edge of scientific thinking. These Principal Essays are arranged in chronological order.

Immanuel Kant’s Critique of Pure Reason is a core text of modern philosophy. Presenting an examination of the nature of human reason, its central argument is that the way in which man perceives his environment is a direct consequence of the mind’s ability to act on this environment and convert it into something meaningful. The work brings together two opposing schools of philosophy—rationalism and empiricism—and proposes a third way, which came to be known as transcendental idealism. The work proved to be hugely influential, not least on Marx, Heidegger and Nietzsche.

As philosophy professor Taylor Carman explains in his helpful introduction, Edmund Husserl (1859-1938) was the founder of modern phenomenology, one of the most important and influential movements of the 20th century. Ideas, published in 1913 – its full title is Ideas for a Pure Phenomenology and Phenomenological Philosophy – was the key work. It is arguably ‘the most fundamental and comprehensive statement of the fundamental principles of Husserl’s mature philosophy’.

Aristotle's Metaphysics was the first major study of the subject of metaphysics - in other words, an inquiry into 'first philosophy', or 'wisdom'. It differs from Physics which is concerned with the natural world: things which are subject to the laws of nature, things that move and change, are measurable. In Metaphysics, the study falls on 'being qua being' - being insofar as it is being; the causes and principles of being, the causes and principles of substances.

The leviathan is the vast unity of the State. But how are unity, peace, and security to be attained? Hobbes’ answer is sovereignty, but the resurgence of interest today in Leviathan is due less to its answers than its methods: Hobbes sees politics as a science capable of the same axiomatic approach as geometry.

Philosophical Investigations was published in 1953, two years after the death of its author. In the preface written in Cambridge in 1945 where he was professor of philosophy he states: ‘Four years ago I had occasion to re-read my first book (the Tractatus Logico-Philosophicus) and to explain its ideas to someone. It suddenly seemed to me that I should publish those old thoughts and the new ones together: that the latter could be seen in the right light only by contrast with and against the background of my old way of thinking.’

John Locke (1632 - 1704), the English philosopher and physician, is widely regarded as one of the Enlightenment's most influential thinkers. "A Letter Concerning Toleration" (1689) addresses the problem of religion and government by proposing religious toleration as the answer. In the "Second Treatise", Locke claims that civil society was created for the protection of life, liberty, and estate.

Published in 1748, An Enquiry Concerning Human Understanding is Scottish empiricist philosopher David Hume's distillation of his mature philosophy. Addressing themes including the limits of human understanding, the compatibility of free will with determinism, weaknesses in the foundations of religion, and the appeal of skepticism, An Enquiry Concerning Human Understanding is Hume's attempt to revise and clarify the ideas of his earlier A Treatise of Human Nature.

From the moment of its publication in 1748, The Spirit of the Laws proved to be a controversial work provoking widespread interest. Within three years it had been translated into various European languages - and was swiftly added to the List of Prohibited Books by the Roman Catholic Church. It is a remarkable book, a potpourri of observations and comments ranging far and wide over the social activities of mankind and it exerted a great influence on political leaders in the following decades.

The Wealth of Nations, first published in 1776, is the first book of modern political economy and still provides the foundation for the study of that discipline. Along with important discussions of economics and political theory, Smith mixed plain common sense with large measures of history, philosophy, psychology, sociology and much else. Few texts remind us so clearly that the Enlightenment was very much a lived experience, a concern with improving them human condition in practical ways for real people.