René Descartes (1596-1650). René Descartes (1596-1650) and Ramiro ______ (198_ - present)

René Descartes (1596-1650)

René Descartes (1596-1650)and

Ramiro ______ (198_ - present)


• mathematician / scientist / philosopher– founder of modern philosophy: overthrew medieval "scholasticism" based on blind acceptance of Aristotle

– inventor of Cartesian (x,y) coordinates– Geometry (1637) expressed geometrical problems in terms of algebra for the first time

• Discourse on Method (1637)• Meditations On First Philosophy (1641)


• method in philosophy should be as objective as that in science (i.e., Galileo)– accept only ideas that are clear and distinct after examination (rationalistic)

– divide problems into as many parts as possible (analytic / atomistic)

– proceed from simplest to complex questions– enumerate steps carefully so as not to neglect any aspect of the thing being studied

• begin by doubting everything that is doubtable, till only doubting remains: "I think, therefore I am."


• ontology: mind-body dualism– two interacting substances

•matter is extended in space, has mass

•mind takes up no space, has no mass

– how do they interact then? Impossible, say the critics!


• epistemology: nativist and rationalist– senses may deceive us; innate ideas (of geometry, self, God) are foundation of knowledge

– mind must make inferences based on inadequate sensory information (poverty of the stimulus)

– homunculus ("little man") problem: explanation of mind's inferential powers is never offered• as if a "little man" inside your head makes the inferences -- so is there a "littler man" inside his head, and so forth?


• described reflex action (and coined the term "reflex")– mechanistic basis of modern physiology and behaviorist psychology

– energy from environment is "relected" back through nervous system

– nerves as tubes allowing flow of "animal spirits," controlled through pineal gland






René Descartes (1596-1650), Meditations on First Philosophy, 1641, Discourse on Method, 1637: proposed dualism, the thesis that mind and body are separate substances (interacting at the pineal gland in the brain) with only the body subject to mechanistic laws of physics -- which leaves the question of how something immaterial could interact with something material; his epistemology claimed that the senses are unreliable and deceptive, so true knowledge must come from the mind's innate ideas (self, God, geometry, and some others) and its direct inspection of the world (which is occasioned by clues from the senses) -- which leaves the question of how to explain the mind's inference-making abilities, without resorting to a "homunculus" that just has those abilities, and the infinite regress of homunculi to explain each previous homunculus's abilities. Since the interaction and homunculus problems are insoluble, the historical effect of Descartes's reasoning was to identify mentalism with dualism and hence to make talk of minds fall outside the purview of science.

John Locke (1632-1704)


John Locke (1632-1704)An Essay Concerning Human Understanding, 1690

- asserted that everything that is in the mind comes to it through the senses - no ideas are innate

- the mind is an active combiner of sensed simple ideas into complex ideas, but perhaps not as much of a manipulator of concepts as the rationalists suppose it to be

- association, though, mainly accounts for IRRATIONALITY

- like Descartes's mind without the innate ideas and the complex inferential abilities

John Locke (1632-1704)Primary Qualities (size, shape, solidity, motion, number) are in the perceived object; Secondary Qualities (like color, sound, taste) depend on a perceiver experiencing them for their existence.

- based on Galileo's distinction between primary and secondary qualities as roughly "objective" and scientific vs. "subjective" and unreliable

- but Locke saw secondary qualities as our mental substitute for perceptual qualities that are too subtle for our senses

- still, he gives the definition of reality over to physics!

John Locke (1632-1704) ?


John Locke (1632-1704), An Essay Concerning Human Understanding, 1690: asserted that everything that is in the mind comes to it through the senses - no ideas are innate; the mind is an active combiner of sensed simple ideas into complex ideas, but not a manipulator of concepts as the rationalists suppose it to be ( -- like Descartes's mind without the innate ideas and the complex inferential abilities); the senses present primary qualities (size, shape, solidity, motion, number) which are in the perceived object, and secondary qualities (like color, sound, taste) that depend on a perceiver experiencing them for their existence.

George Berkeley (1685-1753)



A Treatise Concerning the Principles of Human Knowledge, 1710: Berkeley's view is somewhat like Locke's view but without a real world outside the mind

-Locke's distinction fails since our knowledge of primary qualities comes through the senses (mainly touch) as well

- thus all we have evidence for are the sensations or ideas in our experience, not a world of real objects giving rise to sensation

- sensations cohere within and between individuals, and objects persist with no human present, only because God continually perceives the sensations available to us all.


Unlike Locke: Association is the thing that allows us to link bits of experience together

- it's how we know that different sensory experiences are experiences of the same thing (replacing Aristotle's "common sense")

- New Theory Of Vision (1709): visual sensations (relative size of objects) and touch sensations (moving toward, reaching for, and grasping objects) are associated together in experience, to give us distance perception


George Berkeley (1685-1753), A Treatise Concerning the Principles of Human Knowledge, 1710: argued that Locke's distinction fails since our knowledge of primary qualities comes through the senses (mainly touch) as well; thus all we have evidence for are the sensations or ideas in our experience, not a world of real objects giving rise to sensation ( -- like Locke's view but without the real world outside the mind); sensations cohere within and between individuals, and objects persist with no human present, only because God continually perceives the sensations available to us all.


David Hume (1711-1776)

David Hume (1711-1776)

David Hume (1711-1776)An Enquiry Concerning Human Understanding, 1748A Treatise of Human Nature, 1739

- accepted Berkeley's proposal that we know only ideas

- rejected the notion of mind as an active entity: mind is not an audience for the senses -- mind is the stage itself: merely a locus for the succession of unrelated experiences playing across it

- like Berkeley but without even the mind itself as an active entity

- all complex ideas are built out of simple ideas; all simple ideas are copies of sensations which can be connected according to the laws of association: similarity, contiguity, and causation (no active mental power needed)

David Hume (1711-1776)- causation, however, is reduced to contiguity plus habit (or "custom")

- no logical basis for attributing causality to two temporally contiguous events

- we also expect from habit that the past will be like the future and thus effects will consistently follow their causes

- belief itself is a matter of frequency of exposure (vs. Plato's divided line)

- all knowledge must be about matters of fact or relations among ideas; complex ideas can be analyzed into simple ideas of these two types; any statement which is not one of these must be no more than metaphysical nonsense.

David Hume (1711-1776)David Hume (1711-1776), An Enquiry Concerning Human Understanding, 1748, A Treatise of Human Nature, 1739: accepted Berkeley's proposal that we know only ideas, and also rejected the notion of mind as an active entity: where others saw the mind as the "audience" watching and combining the sensations and ideas it experienced, Hume suggested that there was no audience and that the mind was just the stage itself, merely a locus for the succession of unrelated experiences playing across it ( -- thus his view is like that of Berkeley but without even the mind itself as an active entity); he claimed all simple ideas are copies of sensations (which he termed "impressions"), and can be associated according to laws of similarity (or "resemblance"), contiguity, and causation to form complex ideas -- such lawfulness means that no active agent like the traditional "mind" is needed to account for organized thought; causation, however, is reduced to contiguity plus habit (or "custom") -- there is no logical basis for attributing causality to two temporally contiguous events, but to the extent that we assume from habit that our future experience will be like our past experience, we also expect from habit that effects will consistently follow their causes; he further stated that all knowledge must be about matters of fact or relations among ideas, that complex ideas can be analyzed into simple ideas of these two types, and that any statement which is not one of these must be no more than metaphysical nonsense.

Immanuel Kant (1724-1804)




Critique of Pure Reason, 1781

-instead of innate ideas we must have innate structuring and processing mechanisms which act as filters for experience

- our natural endowment provides us with innate "categories" and "schemas" which impose the ideas of space and time and causality on the naked and logically unrelated sensations that impinge upon us

- like wearing red-colored spectacles would impose a uniform experience of redness on the world if worn from birth

- causality is known to us through more than just habit -- it's a necessary dimension of how our minds present the world to us


Immanuel Kant (1724-1804), Critique of Pure Reason, 1781: to solve Hume's problem and allow for real knowledge (as opposed to mere habits of thought), Kant suggested that instead of innate ideas we must have innate structuring and processing mechanisms which act as filters for experience, i.e., a means for the construction and interpretation of experience; as possessors of minds, our natural endowment provides us with innate "categories" and "schemas" which impose the ideas of space and time and causality on the naked and logically unrelated sensations that impinge upon us, just as red-colored spectacles would impose a uniform experience of redness on the world if worn from birth; thus even though events we observe don't "contain" their causes (as Hume explained), causality is known to us through more than just habit -- it's a necessary dimension of how our minds present the world to us: it describes experience even though it's given before experience. The real existence of causes is a question about the "world-in-itself", or noumenal world -- but since all we can know is the phenomenal world, and since that phenomenal world of experience is necessarily structured by our minds to include causation, it becomes a matter not just of observation but of definition that observed events have causes; therefore, causation is an example of what Kant called synthetic a priori knowledge.

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René Descartes (1596-1650). René Descartes (1596-1650) and Ramiro ______ (198_ - present)