PHILOSOPHICAL RAMIFICATIONS: THEORY, EXPERIMENT, & EMPIRICAL - - PowerPoint PPT Presentation

PHILOSOPHICAL RAMIFICATIONS: THEORY, EXPERIMENT, & EMPIRICAL TRUTH

Even before Newton published his revolutionary work, philosophers had already been trying to come to grips with the questions raised by the new experimental

• philosophy. The work of Bacon, and most of all of Descartes, had forced the issue
• f empirical truth onto centre stage. There were several key questions:

(i) Of w hat are w e sure (is any of our know ledge certain)? This question

was very old but the onslaught of empirical science meant that rationalist (Greek- style or otherwise) or scholastic arguments were now widely rejected.

(ii) What is the stuff of experience (Sense data/mental ‘impressions’). So

the empiricist philosophers turned instead to sense data, or more generally the stuff of direct human experience, as their touchstone. This eventually led to quite fantastic arguments by the British empiricist school (and later on by positivist philosophers on the continent, and eventually in the UK). These ideas were very influential in physics, where they were assimilated to the ‘experimental philosophy’

(iii) What are the influences & constraints imposed by human faculties?

Eventually the obvious point, that human experience was dependent on and indeed constrained by our own sensory and mental faculties, was re-integrated into the discussion, notably by Kant. This almost inevitably led to a re-introduction of an extra-sensory world, beyond our faculties, which constituted a deeper or underlying ‘reality’. The success of new physical ideas inevitably helped this process.

PCES 3.42

BRITISH EMPIRICISM I: Locke & “Sensations”

John Locke (1632-1704)

Locke Locke was the firs was the first Br t Britis itish philosopher o h philosopher of no note after Bacon; his work te after Bacon; his work is a is a reactio reaction to to the Euro the European rationalists, and co pean rationalists, and continues ntinues to elabor to elaborate ‘experimental philosophy’. ate ‘experimental philosophy’. In Locke’s work, all human kno In Locke’s work, all human knowledge ledge is based o is based on experience – experience – the mind is he mind is filled with ‘ideas filled with ‘ideas’ which are entirely hich are entirely derived from experience. T derived from experience. Ther here are Ideas o e are Ideas of ‘sens ‘sensatio tion’, ’, coming via our senses coming via our senses, and o , and of ‘reflectio ‘reflection’, where ’, where the mind the mind

• bserve
• bserves itself and its cont

itself and its contents

• ents. Our unders

. Our understanding tanding o

• f

relatio relations like ‘caus s like ‘causality’ ality’ comes

• mes from the mental oper

from the mental operatio ation n

• f comparing ideas (in the case
• f comparing ideas (in the case of
• f causal

causalit ity, y, of

• f chan

change ges s in sens in sensatio ations ns). K ). Knowledge of ideas is CERTAIN. ledge of ideas is CERTAIN.

We can compare Locke’s ‘mind’ to a TV screen, upon which ideas play in rapid

• succession. Locke imagined that there were

things in the real world (the ‘primary qualities’, independent of us) but we cannot ever know these ‘real things’, only the ‘secondary qualities’ from our senses. Locke’s theory this can say nothing about the relation between the ‘ideas’ & the things they represent. It makes, eg., hallucinations just as certain as any other experience.

Locke’s Magnum Opus

Locke’s sensations: Images on a TV screen PCES 3.43

NOTE on LOCKE’S POLITICAL PHILOSOPHY BRITISH EMPIRICISM II: Berkeley

Britis British Empiricism was stro h Empiricism was strongly influe ngly influenced by the political schisms of the nced by the political schisms of the time, Locke particularly so time, Locke particularly so. His political . His political philosophy (larg philosophy (largely conceived in the ly conceived in the Netherlands when taking Netherlands when taking refuge from refuge from a brief spurt of Catholicism a brief spurt of Catholicism under nder James II) reflects the belief in indivi James II) reflects the belief in individual liberty, perso dual liberty, personal respo al responsibility to sibility to God, and a suspicion of s God, and a suspicion of state control, ate control, current in Britain current in Britain & the Netherlands the Netherlands. This phil This philosophy was enormously

• sophy was enormously influentia

influential in the drafting l in the drafting of

• f legal & political

legal & political fr frameworks in the UK and its colo ameworks in the UK and its colonies nies (parts of the Am (parts of the American Declarati erican Declaration of n of Independence, written by Jefferso Independence, written by Jefferson & Fr n & Franklin, are taken anklin, are taken almost directly almost directly from Locke). Lawyers in these countrie from Locke). Lawyers in these countries s s still read Locke while training ill read Locke while training. A . And d in this way the ideals o in this way the ideals of empirical science came empirical science came to be as to be associated with political liberalism, sociated with political liberalism, justified by the success of Newtonian physics, justified by the success of Newtonian physics, and o and of the future the future Britis British & American empires. h & American empires.

T Jefferson (1743-1826) George Berkeley (1685-1753)

Berkeley’s ideas are sometimes summarized in a limerick according to which a ‘tree only continues to be’ while being observed. Berkeley went much further than Locke, deying any distinction between primary & secondary qualities, & arguing that no object is possible unless it is conceived by the mind:

"No object exists apart from the mind; mind is therefore the deepest reality”

Thus nothing exists apart from what is on the TV screen. According to this view we have no evidence for anything except the sensations & ideas of the

• mind. To the argument that there must be some independent ‘reality’ or

sub-stratum, which ‘supports’ or causes the qualities or sensations, Berkeley responds that this supporting reality is just the percipient mind.

PCES 3.44

BRITISH EMPIRICISM III: Hume

David Hume (1711-1776)

This Scottish philosopher & historian wrote his most important work, the ‘Treatise of Human Nature” at the age of 26; however it was largely unnoticed, falling “deadborn from the press”. Luckily Kant noticed it – it ‘woke him from his dogmatic slumbers’. Hume later became well known as a popular historian. Hume’s book advanced very important arguments which in some ways took empiricism to a logical extreme. His most important points were: (i) The Self: Berkeley, while rejecting the external world, had still argued for a mind or soul, in which sensations and ideas resided. Hume had little difficulty in disposing

• f this –

just as we have no direct experience of any external world, we have none of the ‘self’ . All we know is a disconnected set of impressions. (ii) Causality: In the same way Hume argues that relations like causality , or the identity of a given

• bject, or relations in space & time, are also just

‘associations of impressions’. We believe that A is caused by B because we frequently (or perhaps always) see them together.

These arguments w ere v. influential – they show ed that many things w e take for granted cannot be justified, and led to a sceptical, anti-metaphysical view . They are not perfect (for example, one can ask w hat is associating impressions, if the mind is nothing but these impressions).

ABOVE: Hume’s “History

• f England”

LEFT: 1 st volume of the famous “Treatise”

PCES 3.45

Immanuel KANT: Categories of Understanding

KANT’S CATEGORIES QUANTITY

UNITY, PLURALITY, TO UNITY, PLURALITY, TOTALITY TALITY

QUALITY

REALITY, N ALITY, NEGATION, LIMITATIO GATION, LIMITATION

RELATION

SUBSTANCE & A SUBSTANCE & ACCIDENT NT CAU CAUSALI ALITY & DEPE Y & DEPENDEN ENCE CE INT INTERACTION RACTION

MODALITY

POSS SSIBIL IBILITY – ITY – IMP MPOS OSSIBIL SIBILITY TY EXIS EXISTENCE – TENCE – NON-EXISTENCE

• EXISTENCE

NE NECESSI CESSITY -

• CON

ONTI TINGENCY NGENCY

Kant’s philosophy is somewhat intricat Kant’s philosophy is somewhat intricate – e – it helps to r t helps to remember member wh what he is at he is tryi trying ng to do. First to do. First, he he qu quit ite correct e correctly ly r rejects the id jects the idea th ea that one can treat the at one can treat the conten ents o ts of e exper perien ence without in ce without inco corpor

• rating the ‘observer’

ating the ‘observer’ into the discussion; into the discussion; the cont content & form of our experie & form of our experience mu ce must depend partly on us. Second, he t depend partly on us. Second, he rejects the r jects the rigid distin gid distinction ction between between th the logical and empirical worlds, which e logical and empirical worlds, which goes back to Pla goes back to Plato –

• –

he argues e argues tha that this t this boundary can be crossed. boundary can be crossed.

• 1. Kant w ished to derive from 1 st principles

the w ay in w hich the form & content of experience is molded by the observer. To do this he fell back on Aristotelian ideas, assuming that one could derive ‘categories’

• f understanding from the structure of propositions in language.

These categories correspond to formal features of propositions in language – the idea is that inchoate experience is formless until organised by the categories. Experience here includes all the contents of and processes occurring in our minds. Kant w as making a very bold claim – that he could deduce all those features of our experience that came from our ow n sensory & mental apparatus, and that these features w ere pre-conditions

• f any kind of experience or thought w hatsoever.

2. 2. Kant distinguishes between AN Kant distinguishes between ANALYTIC propositio ALYTIC propositions ns, which are tautolog , which are tautological, and S ical, and SYNTHE NTHETIC TIC propositio propositions ns, where the conclusio , where the conclusion is not cont is not contained in the premises ained in the premises. He also dis . He also distinguishes inguishes between between a prior a priori kno knowledge (true independent o wledge (true independent of experience) & experience) & a posteriori a posteriori knowledge (derived knowledge (derived from experience). Ho from experience). However, he asser wever, he asserts that there exist some synthetic s that there exist some synthetic a priori a priori propositions (eg., propositions (eg., mathematical truths like 3+4 = 7) mathematical truths like 3+4 = 7), which apply to the world of ex , which apply to the world of experie perience (in sharp contrast to ce (in sharp contrast to Hume or Plato, for whom no ce Hume or Plato, for whom no cert rtain/general pr ain/general propositions can apply

• positions can apply to the world o

to the world of experience). experience).

I Kant (1724-1804)

PCES 3.46

Immanuel Kant: Phenomena & Noumena KANT: Space, Time & Causality

If we accept that the organised contents of our minds are now ‘phenomena’ , ie., appearances whose source is both the real world and the categories imposed by our own faculties, it then remains to explain what we are allowed to know about the real world. Kant then argued that there existed a real world of ‘Noumena’, or “things in themselves”, beyond the world of appearances (and beyond our ken as well). Kant was not clear on the ontological status of the phenomena, nor on their exact relationship to the Noumena (and confused things by changing his mind between the 1781 and 1787 editions of his book). But it is logically obvious that the Noumena are themselves unknowable, since we have no direct access to them. A common (but problematic – see below) interpretation of Kant makes them one of the ‘causes’ of the phenomena (the other being our own faculties, as embodied in the categories). Kant give a special discussion of the ideas of space, tim e, and causality – this in direct response to Hum e. Kant’s rather curious view w as that these 3 notions w ere ‘pure intuitions’, w hich w ere not objective or real, but ‘subjective and ideal’, required for the ‘coordinating of all outer sensa’. I n other w ords, they w ere rather like the categories, necessary for experience. Space w as an intuition, necessary for the very notion of geom etry. Likew ise, causation is an ‘a priori synthetic principle’, w ithout w hich know ledge of anything is considered to be im possible. Thus Kant’s answ er to Hum e – that there are general concepts like causation, not derived from experience, yet acting w ithin the w orld of experience. One difficulty here is that the noum ena m ust stand outside these 3 intuitions, so it is hard to see how they can ‘cause’ phenom ena.

PCES 3.47

Ernst Mach (1838-1916)

19 TH CENTURY: Empiricism & Positivism

First photo of a sonic shock w ave (E Mach, 1877)

The 19 he 19th

th

century saw ve century saw very important advances ry important advances in classical physics, no in classical physics, notably the tably the unders understanding o tanding of electromag electromagnetism & netism & heat; the latter was crucial heat; the latter was crucial for new

• r new

industrial techniques. This led to grea industrial techniques. This led to great confidence in the large t confidence in the largely empir y empirical cal methodolo methodology behind these advances. y behind these advances. British philosophy continued to analys British philosophy continued to analyse the r he reasoning underlying em asoning underlying empiric piricism sm. . The social activis The social activist JS Mill attempted to JS Mill attempted to give rules o give rules of inductio induction in science, which n science, which were desig were designed to explicate ed to explicate & jus & justify the use of idea tify the use of ideas li s like causation. Some of ke causation. Some of these rules were no these rules were not original, but the id t original, but the idea of formulating rules

• f formulating rules

for ‘scientific

• r ‘scientific

method’ method’ beyo eyond simple induction, a d simple induction, and to ti d to tie this in with a theory of knowledge, e this in with a theory of knowledge, was important. was important. A new philosophical movement A new philosophical movement, called ‘positivism’, partly inspired by empiricism, , called ‘positivism’, partly inspired by empiricism, grew up in the 2 ew up in the 2nd

nd

half of the 19 half of the 19th

th

• century. In its applicatio
• century. In its application to the sciences

n to the sciences, o , one e

• f its foremost e
• f its foremost exponents was E Mach, al

ponents was E Mach, also an accomplis so an accomplished physicist (kno hed physicist (known wn principally for his studies of supersonic flow principally for his studies of supersonic flow & for & for ‘Mach’s princip Mach’s principle’). e’).

Mach’s ideas w ere peculiar but quite influential, even amongst some experimental physicists. He follow ed the British empiricists in holding that sensations w ere primitive (remarking that “the w orld consists only of

• ur sensations”). Scientific Law s simply linked

sensations, and the only purpose of a theory w as to provide quantitative links. Scientific explanation w as then merely descriptive – in terms of sensations.

John Stuart Mill (1806 – 1873)

PCES 3.48

EARLY 20 TH CENTURY: Verification & Falsification

The 20th century saw very important developments in logic, discussed elsewhere in this course. These naturally spilled over into the philosophy

• f science, and led

some of the logicians to new ideas on the logical underpinnings of science and of

• empiricism. Early developments tried to incorporate these ideas directly (as in

Russell’s ‘logical atomism’, according to which mathematical logic mirrors the structure of reality). But the debate quickly returned to the role of experiment.

The ‘Vienna circle”, started by a group of philosophers & logicians surrounding M. Schlick, argued that the meaning of any statement in language w as found in the means used to empirically verify it – w ithout such means, the statement w as held to be literally meaningless. Hence all of metaphysics w as held to be meaningless – the view of ‘logical positivism’. There are some obvious problems w ith this. First, how is the criterion of verifiability itself meaningful (how is it to be verified)? Second, how is a scientific law itself verifiable – experiments can never guarantee its truth, only confirm it.

These problems led K hese problems led Karl Popper to the id rl Popper to the idea that scientific statements were ea that scientific statements were defined by a criterio defined by a criterion of ‘falsifiabilit

• f ‘falsifiability’

y’

• scientists invent hypo

cientists invent hypotheses about theses about Nature, which can’t be verified by ex ature, which can’t be verified by experiment (this is merely inductive & periment (this is merely inductive & cannot prove hypo cannot prove hypotheses theses), but can be fals ), but can be falsified by a single experiment. This ified by a single experiment. This means that all scientific means that all scientific laws are prov laws are provisional – isional – we can never we can never be sure of them. be sure of them. The mos The most important laws have maxi important laws have maximum simplicity, generality, & also mum simplicity, generality, & also extensive confirmatio extensive confirmation. P . Popper’s ideas pper’s ideas have been very i have been very influential, e fluential, even en thoug though in practise in practise falsificatio falsification does n does no not always kill theories, because the t always kill theories, because the formulation & interpretation of experime formulation & interpretation of experiments itself involves a lot of theory. nts itself involves a lot of theory.

M Schlick (1882-1936) R Carnap (1891-1970)

B Russell (1872-1970)

K Popper (1902-1994)

PCES 3.49