Tas Las Lectures III&IV 2014 15(1)

8/10/2019 Tas Las Lectures III&IV 2014 15(1)

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Lecture 3Modern Rationalism and Empiricism

Lecture 4The Limits of Science: Hume and Kant

Thinking about Science

Dr. Herman C.D.G. de Regt

Department of Philosophy

Faculty of Humanities

Contents

Part 1: After the Revolution:Philosophical Foundations for Science

Part 2: Rationalism again:Against Bacons emphasis on observation

Part 3: Empiricism again:

Against Descartes emphasis on reason

Part 4: Fusion:Kants attempt to ground our knowledge


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Constituting the Revolution

Claudius Ptolemaeus (Ptolemy)(83-168)


Nicolaus Copernicus(1473-1543)

De Revolutionibus


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Johannes Kepler (1609)

Astronomia Nova

Isaac Newton (1687)

Philosophiae NaturalisPrincipia Mathematica

Galileo Galilei (1610)Siderius Nuncius


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Result

Nature of Science

1. Method

> Observation and Induction

> Experiment

2. What do we see?

> The world is a mechanism

> Ask how rather than why

3. Descriptions

> Mathematics

> The machine of the universe

is not similar to a divine

animated being, but similar

to a clock (Kepler)

> Mathematics

(Galileo: geometrics,

Newton: mathematization)

The Universe is a Clock


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New science needs new thinking

about science and knowledge

acquisition

> Empiricism

But not Aristotles empiricism:

> Bacon aims for a total

reconstruction of sciences, arts

and all human knowledge, raised

upon proper foundations

> We need to be aware of the idols:

preconceptions and illusions.

> We need a solid foundation for

science!

Francis Bacon (1561-1626)

Francis Bacon: Plus Ultra

> Instauratio Magna (containsNovum Organon orNewMethod) 1620

> Sailing through the columns of

Hercules (the limits of

knowledge)

why should a few receiedauthors stand u! likeHercules columns"

#any shall !ass to andfro$ and knowledge shall %eincreased&"


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Induction

Plus ultra: Science will take us furtherthan weve ever been

The new method is: Induction

On the basis of a large class ofobservations in which A is(without exception) B, weconclude that All As are B

The emphasis on observations is ahallmark of empiricism

Looking for solid bedrock for science

in Aristotles books [] there is often

discussion of experiments. [ButAristotle] had in fact made up his mind

beforehand, and did not properly

consult experience

--> The danger of biases

Bacons attack on Aristotle


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Idols

(1) Idols of the tribe (idola tribus): false

ideas in our minds that are the result ofthe fact that we are human beingshttp://www.youtube.com/watch?v=7knnO4vKgXg

(2) Idols of the den (idola specus): falseideas in our minds that are the result of

the fact that we are educated in a certainway http://www.youtube.com/watch?v=sYQVDik69Nw

(3) Idols of the market (idola fori): falseideas in our minds that are the result of

the fact that we use language tocommunicate http://www.youtube.com/watch?v=73vGdCaC048(


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Idea Idea: undermining science

Idea Idea

> Reality is not perceiveddirectly

> Reality is perceived byperceiving therepresentations in ourmind

> Arguments?

Illusions

Does anything really move?


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Is there anything really movingin this picture?

Two shades of grey?


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Two shades of grey?

Are there really dots flashing?


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Idea Idea

> Idea Idea> This leads to one of the

most infamous questions ofphilosophy:

If we only seerepresentations of the world,but not the world itself, howdo we know whether therepresentations are true ofthe world?

Is there a world behind this

veil of ideas berhaupt?

.. Do we live in a virtualworld, like The Matrix?

Michel de Montaigne (1533-1592)doubts our knowledge

> If you say that these senseimpressions convey thequality of the outside objectsto our souls by means ofresemblances, how can ourrational soul mae sure thatthey are resemblances, since ithas no direct contact of itsown with the outside objects!"

> It is lie a man who does notnow #ocrates$ if he sees a

portrait of him he cannot saywhether it resembles him ornot"


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Ren Descartes (1596 1650)

Galilei condemned by theChurch;

Studies philosophy in LaFlche: logics, physics,morals, metaphysics,math, music, astronomy;

Spends a long period inthe Netherlands

Quest for Certainty

Answering the new

scepticism, fueled by theIdea Idea

Descartes Rationalism

Descartes rejects both Aristotles andBacons empiricism and defendsrationalism again:

Reason as the source of knowledge

> Doubt experiment: to see what is realknowledge I need to doubt everythingthat I can possibly doubt

But I cannot doubt that I amdoubting! (Cogito ergo sum)

If my ideas are clear and distinct Ican be sure they are true

> Reasoning is the road to knowledge(hence mathematics, deduction, etc.)


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Up to Berkeley

Laws of Economics:derived by reason?

Law of Demand (Adam Smith): If supply is heldconstant, an increase in demand leads to anincreased market price, while a decrease indemand leads to a decreased market price

Derived by reason? Law of Supply: If demand is held constant, anincrease in supply leads to a decreased price, while a decrease in

supply leads to an increased price.

Derived by reason? Law of Diminishing Returns: If one factor ofproduction (number of workers, for example) is increased whileother factors (machines and workspace, for example) are heldconstant, the resulting increase in output will level-off after sometime and then decline.

Antoine Cournot: mathematical model for thelaw of demand in his Recherches sur lesprincipes mathmatiques de la thorie desrichesses(Researches into the MathematicalPrinciples of the Theory of Wealth), 1838

1801-1877

1723-1790


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Laws of Economics:Derived by observations!

Law of Demand (Adam Smith): If supply is heldconstant, an increase in demand leads to anincreased market price, while a decrease indemand leads to a decreased market price

Derived by observation. We have seen numerous times: Ifdemand is held constant, an increase in supply leads to adecreased price, while a decrease in supply leads to an increasedprice. We have concluded that there is a Law of Demand.

Derived by observation. We have seen numerous times: I f onefactor of production (number of workers, for example) is increasedwhile other factors (machines and workspace, for example) areheld constant, the resulting increase in output wil l level-off aftersome time and then decli ne. We have concluded that there is aLaw of Diminishing Returns.

1766 1834

In 1798 the Reverend Thomas Malthus examined theimpact of population growth and reached the somewhatgloomy conclusion that population growth wouldnaturally check itself in the form of famine, wars anddisease. He based this view on the idea thatpopulations tended to grew geometrically (assumingcouples had two or more chil dren)

2,4,8,16, 32, 64while the capacity of l and to produce food tended toincrease arithmetically (the ability to cultivate more land

was less rapid)2,4,6,8,10,12The inevitable conclusion for him was that the

population growth rate outstripped the capacity of landto provide food for the people, ergo starvation andfamine. The theory was based upon what has becomeknown as the law of diminishing returns.

Enter the new empiricists:Locke, Berkeley, and Hume

John Locke (1632-1704)

Essay Concerning Human Understanding (1689)

Empiricist Principle:

'hence has it all the

materials of reason and

knowledge o this * answer$

in one word$ from e%perience&

*n that all our knowledge is

founded$ and from that itultimately deries itself&"


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> "For the Rays (of light) to speak properly are notcoloured. In them there is nothing else than a certainPower and Disposition to stir up a Sensation of this orthat Colour. ... in the Rays they are nothing but theirDispositions to propogate this or that Motion into theSensorium, and in the Sensorium they are Sensationsof those Motions under the form of Colours.

(Newton, Opticks, 1704)

Isaac Newton's diagram of an experiment on l ight with twoprisms. From a letter to the Royal Society, 6th June 1672.

Primary (Original) qualities

> solidity, extension, figure, motion or rest, and

number (II.viii.9)

> they are in the things themselves, whether theyare perceived or no (II.viii 23)

Secondary Qualities

> such qualities which in truth are nothing in theobjects themselves but power to produce various

sensations in us by their primary qualities, i.e. by thebulk, figure, texture, and motion of their insensible

parts, as colours, sounds, tastes, &c. (II.viii.10)

John Locke


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the same fire that, at one distance produces in us

thesensation of warmth, does, at a nearer approach,

produce in us the far different sensation of pain

(II.viii.16)

the same water, at the same time, may produce

the idea of cold by one hand and of heat by the other:whereas it is impossible that the same water, if those

ideas were really in it, should at the same time be

both hot and cold.

(II.viii.21)

The ideas of primary qualities of bodies

are resemblances of them, and theirpatterns do really exist in the bodies

themselves, but the ideas producedin us by secondary qualities have no

resemblance of them at all. There isnothing like our ideas, existing in the bodiesthemselves. They are, in the bodies we

denominate from them, only a power toproduce those sensations in us: and what

is sweet, blue, or warm in idea, is but thecertain bulk, figure, and motion of the

insensible parts, in the bodies themselves (II.viii.15)

Problem: Do ideas mirror reality?

R. Margritte (1928/9)


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Problem: Do ideas mirror reality?

The particular bulk, number, figure, andmotion of the parts of fire or snow are really in

them, whether any ones senses perceivethem or no: and therefore they may be called

real qualities, because they really exist in thosebodies. But light, heat, whiteness, or coldness,are no more really in them than sickness or

pain is in manna. Take away the sensation ofthem; let not the eyes see light or colours, nor

the ears hear sounds; let the palate not taste,nor the nose smell, and all colours, tastes,

odours, and sounds, as they are such particular

ideas, vanish and cease, and are reduced totheir causes, i.e. bulk, figure, and motion of

parts. (II.viii.17)


George Berkeley(1685-1753)


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I see this cherry, I feel it, I taste it: and I am sure nothing cannotbe seen, or felt, or tasted: it is therefore real. Take away thesensations of softness, moisture, redness, tartness, and you takeaway the cherry, since it is not a being distinct from sensations. Acherry, I say, is nothing but a congeries of sensible impressions,or ideas perceived by various senses: which ideas are united intoone thing (or have one name given them) by the mind, becausethey are observed to attend each other. Thus, when the palate isaffected with such a particular taste, the sight is affected with ared colour, the touch with roundness, softness, &c. Hence, when Isee, and feel, and taste, in such sundry certain manners, I amsure the cherry exists, or is real; its reality being in my opinionnothing abstracted from those sensations. But if by the wordcherry you mean an unknown nature, distinct from all thosesensible qualities, and by its existence something distinct from i tsbeing perceived; then, indeed () neither you nor I, nor any oneelse, can be sure it exists. (George Berkeley, Three Dialogues,Part II)

Berkeleys cherry


David Hume (1711-1776):

When we run over libraries, persuaded ofthese [empiriist! priniples, what havomust we ma"e# $f we ta"e in our handan% volume & of divinit% or shoolmetaph%sis, for instane & let us as", Doesit contain any abstract reasoning concerningquantity or number? 'o Does it contain any

experimental reasoning concerning matter offact and existence? 'o ommit it then tothe flames, for it an ontain nothin* butsophistr% and illusion


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Rara temporum felicitas, ubi sentire, qu velis;

& quae sentias, dicere licet.

"Seldom are men blessed with times in which theymay think what they like,

and say what they think."

Tacitus, Historiae (Histories) 100-110 A.C.

David Hume (1711-1776)

Hume: philosopher of the

Enlightenment. But also an

empiricist;

Important distinction between

impressions and ideas:

The famous Copy Principle:

All our ideas are nothing but

copies of our impressions

CP is the first principle in the

science of human nature

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We can even blend ideas:missing shade of blue

Humes devastating critique of science

We normall% sa% that it is theollision of the white movin* ballwith the stationar% red ball thatma"es the red ball move +hemovin* of the red ball is causedb%the ollision with the movin*white ball +he movement of thered ball is the effet 'ow, Humeas"s what we atuall% see or

observe if we onlude that the oneis the ause of the other


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Contiguity: it is evident that the two ballstouhed one another before the motionwas ommuniated, and that there wasno interval betwit the sho" and themotion./

Priority: i t is evident, li"ewise, that themotion whih was the ause is prior tothe motion whih was he effet./ and

Constant conjunction: 0et us tr% an% otherballs of the same "ind in a li"e situation,

and we shall alwa%s find that the impulseof the one produes motion in the other.

Conclusion to the first book


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+he onlusion Hume draws is nothin*less than revolutionar%:

if we understand and reo*nie that thisoperation of the mind.,

(whih onstitutes our apait% to believeon the basis of sense impressions that onethin* is the ause of another thin*),

is itself but the result of a learned habit orustom steered b% passion, we *et aompletel% new view on siene:

Science can never be more than ourbest guess! Theres the Problem ofnduction!

Isaac Newtons laws of motion& law of gravity

I. Every object in a state of uniform motion tends to remainin that state of motion unless an external force is applied toit.

II. The relationship between an object's mass m, itsacceleration a, and the applied force Fis F = ma.

III. For every action there is an equal and oppositereaction.

Fg= The force of gravity (typically innewtons)

G= The gravitational constant, whichadds the proper level of proporti onalityto the equation. The value of Gis6.67259 x 10-11 N * m2/ kg2, although

the value will change if other units arebeing used.

m1 & m1 = The masses of the two

particles (typically in kilograms)

r = The straight-line distance betweenthe two particles (typically in meters)

Nature and Nature'slaws lay hid innight: God said, LetNewton be! and allwas light- Alexander Pope


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Philosophi Naturalis Principia Mathematica (1687)

Economic/financial crisis:Solution?


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Immanuel Kant (1724-1804)

http://en.rian.ru/crime/20130916/183493539/Argument-About-Philosopher-Kant-Ends-With-Russian-Shot-in-Head.html

How to Save Science?


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Answering Humes Critique

Kant appreciates Humes point that we

cannot see, observe, or find thenecessity and universality of events in

our sense experience.

Indeed, Hume is right, Kant says, that

we can only see contiguity, priority, andconstant conjunction.

Still, since we have necessary anduniversal knowledge (such as every

piece of wax melts when heated) wemust explore how such knowledge is

possible.

What Hume forgot was that there simply

issuch knowledge. We need to know

how this is possible.


2ud*mentsaordin* to

Hume and 3ant

4nal%ti(does not expand

existing knowledge)

5%ntheti(expands existing

knowledge)

4 priori

(soure isreason)

Analytic a priori[possible aordin*to both Hume and

3ant!

Synthetic a priori[possible aordin* to

3ant, impossibleaordin* to Hume!

4 posteriori

(soure iseperiene)

[impossibleaordin* to bothHume and 3ant!

Synthetic a posteriori[possible aordin* to

both Hume and 3ant!


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2ud*mentsaordin* to

Hume and 3ant

4nal%ti(does not expand

existing knowledge)

5%ntheti(expands existing

knowledge)

4 priori

(soure isreason)

4 posteriori

(soure is

eperiene)

Impossible

If supply is held

constant, an increase

in demand leads to an

increased market

price, while a

decrease in demand

leads to a decreased

market price

The profitconstitutes a

positive differencebetween the firms

income andeconomic costs

The USGoverment has

bailed out Fanny

Mae and FreddieMac

How scientific knowledge is possible

Reason

Senses}

Empirical world(Content)

Categories

(Form)

+Scientific

knowledge

Match


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When scientific knowledgeis not possible

Reason

Senses}


Categories

(Form)

+Scientific

knowledge

Match

?Pure registration:senseless data

When scientific knowledgeis not possible

Reason

Senses}


Categories

(Form)

+Scientific

knowledge

Match

?

Pure speculation:

God, soul, universe


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Conclusion

Science is our best guess

Advantage: our passions let us survive

Disadvantage: no rock bottom for science

Science constitutes knowledge

Advantage: rock bottom for scienceDisadvantage: frustratingly limited to

down-to-earth human knowledge

Either way: Science is not without limits

Tas Las Lectures III&IV 2014 15(1)

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