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Philosophy 
RATIONALISM PERIOD
WHAT IS PHILOSOPHY? 
“Philosophy is the study of general and fundamental  
problems, such as those connected with reality, existence, 
knowledge, values, reason, mind and language.” 
Barry Smith said that,  
“Philosophy is thinking fundamentally, clearly and well  
about the nature of reality and our place in it, so as to 
understand better what goes on around us and what our 
contribution is to the reality, and its effect on us.”
RATIONALISM: 
Humans can arrive at truth by reasoning 
(understanding obtained through cause 
and effect logic) rather than by relying on 
past authorities, religious faith or 
intuition.
RATIONALISM: 
Rationalism is an epistemological position in 
which reason is said to be the primary source of 
all knowledge, superior to the senses. 
In general, rationalists believe that abstract 
reasoning can produce undeniable, absolutely 
certain truths about nature, existence, and the 
whole of reality. 
These truths are called a priori, or innate, ideas – 
because they are discovered independently of 
experience, without empirical observation or 
experimentation.
 According to rationalists, there is no other way of 
getting knowledge except reasoning. 
 Rationalism view is opposite to empiricism which 
says that all knowledge comes from sense 
experience. 
 This is commonly called Continental Rationalism 
because it was predominated in the continental 
schools of Europe, whereas in Britain empiricism 
dominated. 
 Most prominent rationalists were Descartes, 
Spinoza and Leibniz.
HISTORY OF RATIONALISM: 
 Rationalism is a Latin word which means Reason. 
 Many of the great philosophers from antiquity laid 
down the foundation of rationalism. Pythagoras, Plato 
and Aristotle were among the first philosophers who 
talked about reason. But they themselves were not 
rationalists. Descartes was the first modern 
philosopher who took the true rationalistic view by 
starting doubting everything even his own existence. 
He wanted to know if there is anything in this world 
that we can know for sure. His work was followed and 
further developed by other rationalists like Spinoza 
and Leibniz.
ESSENTIAL THESES OF RATIONALISM: 
 At its core, rationalism consists of three basic 
claims. For one to consider themselves a 
rationalist, they must adopt one of these 
three claims: 
1. The intuition/Deduction thesis 
2. The innate knowledge thesis 
3. The innate concept thesis
THE INTUITION/DEDUCTION THESIS 
 It states that some subjects are knowable by 
intuition alone, while some are knowable by 
being deduced from intuited propositions. 
 Intuition means that we simply see something to 
be true. 
 Deduction is a process in which we draw 
conclusion based on valid arguments presented 
to us, in one way or other. 
 Intuition and deduction combine to give us 
proper knowledge.
THE INNATE KNOWLEDGE THESIS: 
 It states that we have knowledge of some truths as 
part of our rational nature. 
 It means that our innate knowledge is not acquired 
through experience, intuition or deduction. It is a part 
of our nature. 
 Philosophers have different views of how this 
knowledge comes to us. Some believe that God 
granted us this knowledge at our creation, and some 
believe that it became part of our nature through 
natural selection. 
 e.g. , Descartes discussed that the idea of God is 
present in our rational nature.
THE INNATE CONCEPT THESIS: 
 It states that some of the concepts are part of 
human’s rational nature and does not require 
experience to unlock it. 
 It means that experience does not provide 
the concepts that we have but they are part 
of our rational nature and we know them 
naturally. 
 John Locke argued that The Innate 
Knowledge Thesis and The Innate Concept 
Thesis are one and same.
NON-ESSENTIAL THESES OF RATIONALISM: 
 There are two non-essential theses that may 
or may not be adopted by rationalists: 
1. The indispensability of reason: it states 
that experience cannot provide what we 
gain from reason. 
2. The superiority of reason: it states that the 
greatest way to gain knowledge is through 
reason and not through experience.
WORK OF FAMOUS RATIONALISTS: 
 Rene Descartes (1596-1650) : He is often called 
the Father of modern philosophy. He is one of the 
earliest and best known proponents of rationalism. 
He believed that knowledge of eternal truths could 
be attained by reason alone, without the need of 
any sensory experience. He said that only those 
ideas are valid which come to us from God. His 
famous dictum “Cogito ergo sum”(I think, therefore I 
am) is also a conclusion reached through innate 
knowledge and not through experience. He saw 
nature as a mechanism that can be explained 
mathematically, while God is pure spirit.
 Baruch Spinoza (1632-1677) : He expanded 
upon Descartes’ basic principles of rationalism. 
His philosophy centered on many principles, 
most of which relied on his notion that God is 
the only absolute substance, and that substance 
is composed of two attributes, thought and 
extension. He believed that all aspects of 
natural world(including man) were modes of 
eternal substance of God, and can therefore 
only be known through pure thought or reason.
 Gottfried Leibniz (1646-1716) : He believed 
that ideas existed in the intellect innately, but 
only in a virtual sense, and it is only when the 
mind reflects on itself that those ideas are 
actualized. Gottfried Leibniz attempted to rectify 
what he saw as some of the problems that 
were not settled by Descartes by 
combiningDescartes' work with Aristotle's notion 
of form and his own conception of the universe 
as composed of monads.
 Nicolas Malebranche (1638-1715) : He 
was a follower of Descartes and believed 
that humans attain knowledge through ideas 
rather than sensory perceptions. He argued 
that all ideas existed only in God and that 
God was the only active power. And when we 
access those ideas intellectually, we 
apprehend objective truth.
WORK OF IMMANUEL KANT : 
 He is considered to be most important 
modern philosopher because he built a 
bridge between rationalism and empiricism. 
He believed that all knowledge comes from 
the senses but is filtered through our rational 
minds. Therefore there is a difference 
between how things really are and how 
things are experienced by us.
SO…. 
Philosophical rationalism encompasses 
several strands of thought, all of which 
usually share the conviction that reality is 
actually rational in nature and that making 
the proper deductions is essential to 
achieving knowledge

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Rationalism

  • 2. WHAT IS PHILOSOPHY? “Philosophy is the study of general and fundamental  problems, such as those connected with reality, existence, knowledge, values, reason, mind and language.” Barry Smith said that,  “Philosophy is thinking fundamentally, clearly and well  about the nature of reality and our place in it, so as to understand better what goes on around us and what our contribution is to the reality, and its effect on us.”
  • 3. RATIONALISM: Humans can arrive at truth by reasoning (understanding obtained through cause and effect logic) rather than by relying on past authorities, religious faith or intuition.
  • 4. RATIONALISM: Rationalism is an epistemological position in which reason is said to be the primary source of all knowledge, superior to the senses. In general, rationalists believe that abstract reasoning can produce undeniable, absolutely certain truths about nature, existence, and the whole of reality. These truths are called a priori, or innate, ideas – because they are discovered independently of experience, without empirical observation or experimentation.
  • 5.  According to rationalists, there is no other way of getting knowledge except reasoning.  Rationalism view is opposite to empiricism which says that all knowledge comes from sense experience.  This is commonly called Continental Rationalism because it was predominated in the continental schools of Europe, whereas in Britain empiricism dominated.  Most prominent rationalists were Descartes, Spinoza and Leibniz.
  • 6. HISTORY OF RATIONALISM:  Rationalism is a Latin word which means Reason.  Many of the great philosophers from antiquity laid down the foundation of rationalism. Pythagoras, Plato and Aristotle were among the first philosophers who talked about reason. But they themselves were not rationalists. Descartes was the first modern philosopher who took the true rationalistic view by starting doubting everything even his own existence. He wanted to know if there is anything in this world that we can know for sure. His work was followed and further developed by other rationalists like Spinoza and Leibniz.
  • 7. ESSENTIAL THESES OF RATIONALISM:  At its core, rationalism consists of three basic claims. For one to consider themselves a rationalist, they must adopt one of these three claims: 1. The intuition/Deduction thesis 2. The innate knowledge thesis 3. The innate concept thesis
  • 8. THE INTUITION/DEDUCTION THESIS  It states that some subjects are knowable by intuition alone, while some are knowable by being deduced from intuited propositions.  Intuition means that we simply see something to be true.  Deduction is a process in which we draw conclusion based on valid arguments presented to us, in one way or other.  Intuition and deduction combine to give us proper knowledge.
  • 9. THE INNATE KNOWLEDGE THESIS:  It states that we have knowledge of some truths as part of our rational nature.  It means that our innate knowledge is not acquired through experience, intuition or deduction. It is a part of our nature.  Philosophers have different views of how this knowledge comes to us. Some believe that God granted us this knowledge at our creation, and some believe that it became part of our nature through natural selection.  e.g. , Descartes discussed that the idea of God is present in our rational nature.
  • 10. THE INNATE CONCEPT THESIS:  It states that some of the concepts are part of human’s rational nature and does not require experience to unlock it.  It means that experience does not provide the concepts that we have but they are part of our rational nature and we know them naturally.  John Locke argued that The Innate Knowledge Thesis and The Innate Concept Thesis are one and same.
  • 11. NON-ESSENTIAL THESES OF RATIONALISM:  There are two non-essential theses that may or may not be adopted by rationalists: 1. The indispensability of reason: it states that experience cannot provide what we gain from reason. 2. The superiority of reason: it states that the greatest way to gain knowledge is through reason and not through experience.
  • 12. WORK OF FAMOUS RATIONALISTS:  Rene Descartes (1596-1650) : He is often called the Father of modern philosophy. He is one of the earliest and best known proponents of rationalism. He believed that knowledge of eternal truths could be attained by reason alone, without the need of any sensory experience. He said that only those ideas are valid which come to us from God. His famous dictum “Cogito ergo sum”(I think, therefore I am) is also a conclusion reached through innate knowledge and not through experience. He saw nature as a mechanism that can be explained mathematically, while God is pure spirit.
  • 13.  Baruch Spinoza (1632-1677) : He expanded upon Descartes’ basic principles of rationalism. His philosophy centered on many principles, most of which relied on his notion that God is the only absolute substance, and that substance is composed of two attributes, thought and extension. He believed that all aspects of natural world(including man) were modes of eternal substance of God, and can therefore only be known through pure thought or reason.
  • 14.  Gottfried Leibniz (1646-1716) : He believed that ideas existed in the intellect innately, but only in a virtual sense, and it is only when the mind reflects on itself that those ideas are actualized. Gottfried Leibniz attempted to rectify what he saw as some of the problems that were not settled by Descartes by combiningDescartes' work with Aristotle's notion of form and his own conception of the universe as composed of monads.
  • 15.  Nicolas Malebranche (1638-1715) : He was a follower of Descartes and believed that humans attain knowledge through ideas rather than sensory perceptions. He argued that all ideas existed only in God and that God was the only active power. And when we access those ideas intellectually, we apprehend objective truth.
  • 16. WORK OF IMMANUEL KANT :  He is considered to be most important modern philosopher because he built a bridge between rationalism and empiricism. He believed that all knowledge comes from the senses but is filtered through our rational minds. Therefore there is a difference between how things really are and how things are experienced by us.
  • 17. SO…. Philosophical rationalism encompasses several strands of thought, all of which usually share the conviction that reality is actually rational in nature and that making the proper deductions is essential to achieving knowledge