section_path: History/Modern/Early modern (17th and 18th centuries)
section_name: Early modern (17th and 18th centuries)
paragraph_text: Early modern (17th and 18th centuries)
  
  Some central topics of Western philosophy in its early modern (also classical modern) period include the nature of the mind and its relation to the body, the implications of the new natural sciences for traditional theological topics such as free will and God, and the emergence of a secular basis for moral and political philosophy. These trends first distinctively coalesce in Francis Bacon 's call for a new, empirical program for expanding knowledge, and soon found massively influential form in the mechanical physics and rationalist metaphysics of René Descartes.
  
  Descartes's epistemology was based on a method called Cartesian doubt, whereby only the most certain belief could act as the foundation for further inquiry, with each step to further ideas being as cautious and clear as possible. This led him to his famous maxim cogito ergo sum ('I think, therefore I exist'), though similar arguments had been made by earlier philosophers. This became foundational for much of further Western philosophy, as the need to find a route from the private world of consciousness to the externally existing reality was widely accepted until the 20th century. A major issue for his thought remained in the mind–body problem, however. One solution to the problem was presented by Baruch Spinoza, who argued that the mind and the body are one substance. This was based on his view that God and the universe are one and the same, encompassing the totality of existence. In the other extreme, Gottfried Wilhelm Leibniz, argued instead that the world was composed of numerous individual substances, called monads. Together, Descartes, Spinoza and Leibniz are considered influential early rationalists.
  
  In contrast to Descartes, Thomas Hobbes was a materialist who believed that everything was physical, and an empiricist who thought that all knowledge comes from sensation which is triggered by objects existing in the external world, with thought being a kind of computation. John Locke was another classic empiricist, with his arguments helping it overtake rationalism as the generally preferred approach. Together with David Hume, they form the core of 'British empiricism'. George Berkeley agreed with empiricism, but instead of believing in an ultimate reality which created perceptions, argued in favour immaterialism and the world existing as a result of being perceived. In contrast, the Cambridge Platonists continued to represent rationalism in Britain.
  
  In terms of political philosophy, arguments often started from arguing over the first principles of human nature through the thought experiment of what the world would look like without society, a scenario referred to as the state of nature. Hobbes believed that this would be a violent and anarchic, calling life under such a state of affairs "solitary, poor, nasty, brutish and short". To prevent this, he believed that the sovereign of the state should have essentially unlimited power. In contrast, Locke believed the state of nature be one where individuals enjoyed freedom, but that some of that (excluding those covered by natural rights) had to be given up when forming a society, but not to the degree of absolute rule. Jean-Jacques Rousseau meanwhile argued that in nature people were living in a peaceful and comfortable state, and that the formation of society led to the rise of inequality.
  
  The approximate end of the early modern period is most often identified with Immanuel Kant's systematic attempt to limit metaphysics, justify scientific knowledge, and reconcile both of these with morality and freedom. Whereas the rationalists had believed that knowledge came from a priori reasoning, the empiricists had argued that it came from a posteriori sensory experience, Kant aimed to reconcile these views by arguing that the mind uses a priori understanding to interpret the a posteriori experiences. He had been inspired to take this approach by the philosophy of Hume, who argued that the mechanisms of the mind gave people the perception of cause and effect.
  
  Many other contributors were philosophers, scientists, medical doctors, and politicians. A short list includes Galileo Galilei, Pierre Gassendi, Blaise Pascal, Nicolas Malebranche, Antonie van Leeuwenhoek, Christiaan Huygens, Isaac Newton, Christian Wolff, Montesquieu, Pierre Bayle, Thomas Reid, Jean le Rond d'Alembert and Adam Smith.