This document discusses the differences between rationalism and empiricism in epistemology. Rationalism holds that there are innate ideas that cannot come from experience alone, while empiricism believes that all knowledge comes from sensory experience. Key rationalist philosophers discussed include Descartes, Spinoza, and Leibniz. Descartes used rational intuition and deduction to establish certainty. Spinoza believed God, nature, and mind were one substance. Leibniz argued against the tabula rasa view and proposed parallelism between mind and body with preestablished harmony.

1. Rationalism
The Geometry of the Mind

2. Empiricism vs. Rationalism
 Basic differences between empiricism and rationalism
 Empiricists describe a somewhat passive mind which acts in mechanical
way
 Rationalists proposed an active mind that acts on information from the
senses and gives it meaning
 Empiricists proposed that experience, memory, associations, and
hedonism determine not only how a person thinks and acts but also his
or her morality.
 For rationalists, there are rational reasons some acts or thoughts are
more desirable than others
 Empiricists emphasize mechanical causes of behavior
 Rationalists emphasize reasons for behavior
 Epistemological distinction:
 Innate ideas: cannot arise from experience and upon which, given
sufficient developmental maturity, will come to be known as certain
 Methodological distinction:
 Relative roles of induction vs. deduction

3. Chronological distinction
 Plato’s nativism (truths are within our souls,
such that through discovery, we ‘remember’
them) vs. Man as the measure of all things
 Aristotle’s ‘common-sense’ approach- senses
are accurate and reason can grasp the truth by
means of sense information
 In middle age Scholasticism we had the
problem of universals
 If there are universals one is assuming some
‘extra-sensory’ knowledge
 Now, Empiricism vs. Rationalism

4. Rene Descartes
 1596-1650
 Discourse on Method, Meditations
 Descartes sought to devise a
system of explanation of the
universe that could not be
questioned and developed by self-exploration
and observation.
 Method was to determine that
which was certain and then
deduce other certainties
(deductive method)
 Like Bacon, the enemy for Descartes
was Renaissance skepticism, though
is going about his battle in opposing
fashion

5. Rene Descartes
 Method:
 Accept nothing as true but that which is so
clear no uncertainty regarding it remains
 Divide a problem into more simple elements
 Solve the smallest problems first and work
your way up
 Make sure that the conclusion is general
enough to have no exception

6. Rene Descartes
 Starting point: skepticism, distrust of the
senses
 How far can we go?
 Can we even doubt ourselves?
 We cannot doubt ourselves, for that which
doubts must exist; ideas must exist or doubt
is impossible
 Cogito ergo sum
 Reason provides undeniable proof to
existence

7. Rene Descartes
 Through analysis of own thoughts he determined
that some ideas are innate (natural components of
the mind)
 Among innate ideas were unity, infinity, perfection,
axioms of geometry, and God.
 Was also a phenomenologist
 Studied the nature of intact, conscious experience
 In addition to the validity of rational processes,
knowledge gained through the senses could be
accepted because God, being perfect, would not
and could not deceive us
 Sensory information had to be analyzed rationally to
determine its validity
 Opposite Bacon, we must first begin with reason before
conducting experiments
 Essentially the hypothetico-deductive method of today

8. Rene Descartes
 Descartes explained the behavior of animals
including humans employing mechanical
principles
 The nervous system was a set of hollow tubes
connecting the sense receptors with cavities in
the brain (the ventricles)
 The system contained animal spirits which flow
through the nerves resulting in sensation and
movement
 By explaining both animal and human
behavior in terms of mechanistic principles
and reflexes he made comparative
psychology legitimate

9. Rene Descartes
 For Descartes an important difference between animals and
humans was that only humans have a mind which provided
consciousness, free will, and rationality
 The mind, however, was nonphysical and the body was
physical
 Mind consists thought, which is that which compels us to act or is
that which is responsible for feeling
 The nonphysical mind and the physical body can influence
each other, thus, regarding the mind-body issue he was a
dualist and an interactionist
 Having no real way of showing how this could be, he
determined that the mind/soul influenced the body at the
pineal gland in the brain as it was not duplicated like all other
brain structures
 We now know it to have its own hemispheres

10. Rene Descartes
 Among Descartes’ contributions to psychology are:
 1. The mechanistic explanations of behavior and
many bodily functions which could be said to have
led to stimulus-response explanations and
behaviorism.
 2. The focus on the brain as an important mediator
of behavior.
 3. His description of the mind-body relationship
which provided others the opportunity to support or
refute it.
 4. His study of the bodies of animals as a means to
understand the functioning of human bodies led to
physiological and comparative psychology.
 5. He paved the way for the scientific study of
consciousness.

11. Blaise Pascal
 1623-1662
 Pensees
 Although accomplishments more of the science and
mathematical nature, was also staunchly against the
rationalism of Descartes
 "I cannot forgive Descartes; in all his philosophy he did his best to
dispense with God. But he could not avoid making Him set the
world in motion with a flip of His thumb; after that he had no more
use for God."
 “Experiments are the true teachers which one must follow in
physics."
 Pascal’s wager
 Believe in God just in case. What do you have to lose?
 Note that although we might put Pascal as anti-Cartesianism,
he was in general anti-reason, whether a priori (rationalism) or
based on sense (empiricism)
 Sense argument as usual, but the a priori ‘truths’ assume others,
which assume other truths and so on, such that we can’t really get
to the original truths
 Tweener

12. Spinoza
 1632 – 1677
 Descartes had clearly separated mind,
matter and God and Spinoza, while
being placed in the rationalist camp,
offers what would be a much different
take on matters
 For him he saw no experiential or
rational reason for that distinction
 The ‘new’ science must in some way
take on God or remove him completely

13. Spinoza
 Proposed that God, nature, and mind were aspects
of the same substance (inseparable).
 “Things which have nothing in common cannot be one the
cause of the other”
 If God is the author of all things, His presence must be in
all
 God was nature, to understand nature is to
understand God.
 Pantheism- God is present everywhere and in everything.
 The mind-body issue was dealt with by assuming
that the mind and body were two aspects of the
same thing (double aspectism)
 Upon death, one survives as the idea of their
essence is retained in the mind of God

14. Spinoza
 As God is the cause of all things we do not have
free will.
 Nature (God) is lawful, humans are part of nature, thus
thoughts and behavior are lawfully determined.
 “The mind is determined to wish this or that by a cause,
which has also been determined by another cause… and
so on to infinity.”
 Man’s idea of free will is due to ignorance regarding
possible causes
 Our “freedom” is realizing that everything that is
must necessarily be and everything that happens
must necessarily happen - because everything
results from God.
 Stoic

15. Spinoza
 Categories of Spinoza’s psychology
 Passion
 A feeling about which we have no idea attached (blind rage)
 Emotion
 Shaped by a distinct idea (love for fellow man)
 Reason
 Intuition
 Learning and memory
 Memory is enhanced or degraded based on the contextual
details of the material to be memorized
 Interference from learning similar material
 Memory is a brain process
 Every idea has a correlate in the real world
 Distinguishes sensation from perception

16. Spinoza
 In terms of good and evil, they are ‘nothing
else but the emotions of pleasure and pain’
 Pleasure and pain as the mind’s recognition of
its strengths and weaknesses
 Ordinary folk go about seeking for pleasure
without the application of reason (a clear idea)
 The goal of human psychology is self-actualization
 Driven to create pleasure in the mind and work toward
our essence, pain arising due to its denial

17. Nicolas de Malebranche
 1638 - 1715
 "We must follow reason despite the caresses,
the threats and the insults of the body to which
we are conjoined, despite the action of the
objects that surround us....I exhort you to
recognize the difference there is between
knowing and feeling, between our clear ideas,
and our sensations always obscure and
confused."
 God mediated mind – body interaction.
 When a person has a desire to move a part of
the body, God is aware of this and moves the
body part (occasionalism).

18. Gottfried Wilhelm von Leibniz
 1646 - 1716
 Voted best hair in philosophy 1700-
1702
 Specifically disagreed with Locke
and the notion of a tabula rasa
 Some thing has to have an experience
and be prepared in some way to have
experiences of varying kinds
 Empiricist thinking “Nothing is in the
intellect which was not first in the
senses.”
 Leibniz “Nothing except the intellect
itself.”
 Was also not so keen on
Descartes’ brand of dualism

19. Leibniz
 Ideas, being immaterial, cannot be caused by the senses
 Nonreductionist- ideas/perception cannot be reduced to
sensations
 Experience allows us to discover or take notice of ideas that
are in us
 Provides a context for thought
 Regarding the mind-body issue, he proposed a
psychophysical parallelism with a preestablished harmony
 Parallelism
 The mind and body appear to influence each other but they do
not, work in parallel
 Work in harmony established by God
 There are perceptions (which are purely psychological events
driven by reason) which are conscious and those which are
below consciousness
 Reach a threshold and become conscious
 Note that this is not in any way a precursor to Freud’s
unconscious as there is no talk of motivation or psychopathology

20. Leibniz
 For Leibniz, the universe consisted of an
infinite number of simple/irreducible/
dimensionless units called monads
 Can be seen as a ‘living atom’, active and
conscious
 Mind as monad
 Monads differ in clarity of consciousness in
a hierarchy
 In general the hierarchy goes from God, the
highest, to humans, followed by animals, plants,
and nonliving matter

21. Immanuel Kant
 1724 – 1804
 One of the most influential
philosophers of all time
 Critique of Pure Reason
 Had done much philosophical and
scientific work up until age 46 when
realized that he hadn’t really
addressed the argument of the
senses vs. the intellect
 Spent 10 years on the Critique in
an attempt to solve the problem

22. Immanuel Kant
 Initial distinction
 Analytical statements
 Predicate is contained within the subject, the proposition adds nothing to the
subject
 Cars are motorized vehicles
 Synthetic statements
 Do add something
 Milk does a body good
 The empiricists (Hume in particular) suggest analytical statements
are
 Logically necessary (if true are necessarily so)
 Certain as opposed to probable
 A priori as opposed to experiential
 Synthetic statements are
 Contingently, not necessarily, true
 Probable, never certain
 A posteriori
 Kant was to suggest that some synthetic statements can be a priori
truths

23. Immanuel Kant
 Kant agrees with the Empiricists as we have
presented them (e.g. sense as starting
point, judgments of experience are
synthetical etc.), however wants to
determine the limits of empiricism
 Causality- how do we get to it?
 Recall Hume’s stance:
 There is no necessity to an assessment of
causation
 Causality (including moral law derived from it) is
a result of experience only, and we can never
prove a causal relationship

24. Immanuel Kant
 Starting point
 ‘Experience is possible only through the
representation of a necessary connection of
perceptions’
 ‘Everything that happens, that is, begins to be,
presupposes something upon which it follows
according to a rule’
 Recall that Hume suggested causality is
derived from things like contiguity in space
and time
 B always follows A
 Kant asks, From whence time?

25. Immanuel Kant
 The argument:
 A. An object must exist in time to have any real existence
(following our second starting point, it follows something else in
time necessarily)
 B. We can distinguish an event from an enduring state of affairs
in serial fashion, and such a change has a cause
 C. Hume states that for a cause and effect relation to be
determined, C & E must be contiguous in time (and space),
and through repetition we can inductively conclude the relation.
 However time is not given to our experience by the object
itself, but rather permanence is understood a priori such that
we can see it as existing in time
 The reply: Unless there was some a priori category of
understanding (time) how would we make the association in
time to begin with?
 Hume’s stance (B&C) implies Kant’s (A), i.e. an a priori
understanding must be available in order to experience a causal
event psychologically

26. Immanuel Kant
 Kant proposed that the mind must add something to sensory
data before knowledge could be attained, that something was
provided by a priori categories of thought
 Empirical knowledge, though granted, is not sufficient to explain
the attainment of all knowledge without reference to an a priori
understanding
 These categories contain the possibility of all experience in
general
Concept of Quantity Concept of Quality
Unity
Reality
Plurality
Negation
Totality
Limitation
Concept of Relation Concept of Modality
Inherence & Subsistence
Cause and Effect
Community
Possibility-Impossibility
Existence-Nonexistence
Necessity-Contingency

27. Immanuel Kant
 Our mental experience is always structured
by the categories of thought
 Thus our phenomenological experience
(subjective mental experience) is an
interaction of sensations and the categories
of thought
 We can never know the true physical,
objective reality (noumena), just
appearances (phenomena) that are
controlled by the categories of thought

28. Immanuel Kant
 A basis is now provided to move away from the
‘pleasure principle’ stance of the Empiricists
 Laws of experience are authored by those of reason
 Not enough to judge good and evil based on feeling
unless can explain how the feeling attaches to the
act
 The attachment assumes a rule, a rational principle
which governs or should govern moral behavior
 The Categorical Imperative:
 Act in such a way that the maxim of your action could
serve as a universal law

29. Immanuel Kant
 Such ideas had wide ranging influence on later
psychologists
 The concepts of innate logical structure to language and
thought, a priori principles of perceptual organization etc.
affect every branch save perhaps physio and strict
behaviorism
 However while giving us back mind (over the
senses), he did to some extent stall the study of it
 Not too sure about a true science of the mind
 Provided the Psychological Uncertainty Principal
 Merely observing the contents of mind alters it
 Furthermore, the a priori categories are not amenable to
empirical investigation by definition

30. The Rationalist Legacy
 Science would initially draw upon both rationalistic
and empiricist tenets while not strictly adhering to
either, though empiricism would in a sense win out
 In fact, much of psychology implicitly assumes a
materialistic stance
 However we do see it’s resurgence in current
developmental psychology and our understanding
of language
 Furthermore cognitive psychology as a whole
explicitly assumes the Kantian contribution of
having both bottom-up (sense-driven) and top-down
affects on experience and understanding