1. Philosophy
RATIONALISM PERIOD

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