The Existence of MatterThe Existence of Matter

The Problem of Perception and the External World

Bertrand RussellBertrand Russell

Whoever wishes to become a philosopher must learn not to be frightened by absurdities.

------Bertrand Russell, Problems of Philosophy

An Old ProblemAn Old Problem

• Are things as they seem?

• Are there objects independent of me?

• Are there other minds?

• And even if there are…

• …how could I ever know any of these things?

Skepticism about the External World

Causes of my experiences?Causes of my experiences?

• External objects?

• Berkeley’s God?

• Updated version of Berkeley’s God: I’m a brain in a vat and a computer is feeding in experiences?

It was at that precise moment that Stanley realized that he may very well be a brain in a vat.

Problem: how to avoid skepticismProblem: how to avoid skepticism

Direct (“Naïve”) Realism: physical objects are directly (“immediately”) perceived

We don’t need to justify an inference from sensory experience to physical reality because physical objects are the objects of sensory experience.

Sense Data Theories:the objects of immediate experience are sense data—private, non-physical entities, “ideas”

• Representationalism (indirect realism): the immediate objects of experience represent the physical objects which cause them

• Phenomenalism: physical objects are reducible to the occurrence of the immediate objects of experience

The Classic Alternatives

Direct & Indirect Realism failDirect & Indirect Realism fail

Direct Realism: we do need justification for beliefs about physical objects.

• Argument from illusion: cases of non-veridical perception

• Argument from perspectival differences

• Argument from the scientific account of perception: the intervening medium affects experience, the finite speed of light.

• Representationalism: we can’t know either that there are objects outside of experience that cause experience or that whatever objects there are ‘out there’ resemble the objects of immediate experience (i.e. sense data)

• We can’t observe the alleged causal connection.

• We can’t observe the alleged resemblance.

Russell argues that neither direct realism nor indirect realism can get us out of skepticism.

RepresentationalismRepresentationalism

Vei

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f P

erce

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What’s the problem with this picture?

What we need to doWhat we need to do

• Avoid skepticism: give good reason for our commonsense belief that there is an “external world”

– Why? Because that’s what philosophers do: “philosophy leaves everything as it is.”

• Explain the relation between our sense data and physical objects

– Phenomenalism: physical objects are “logical constructions” out of sense-data—”permanent possibilities of sensation” (Mill)

• Explain the relation between our sense data and us—and other people’s sense data and them

– Neutral Monism: physical objects and “selves” (minds) are constructed out of the same (“neutral”) items but in different ways.

What Russell Will DoWhat Russell Will Do

• Russell will rehearse the case for skepticism

– Hard and soft data: logical facts and facts about sense data are all that are certain

• How the question should be put: “independent of ourselves” won’t do because

– What is the self?

– What is meant by independent?

• An hypothesis to fit commonsense talk

– physical objects as logical constructions

What is What is ““givengiven”” in sense in sense

The first thing that appears when we begin to analyze our common knowledge is that some of it is derivative and some of it is primitive…the immediate facts perceived by sight or touch or hearing do not need to be proved by argument…[but] what is actually given in sense is much less than most people would naturally suppose and…what at first sight seems to be given is really inferred.

• Sense perception is “constructive”: not all is “given”

– We fill in the details: listening to English vs. foreign language, seeing faces, reading people’s expressions, etc.

– We (unconsciously) make assumptions, e.g. about the persistence of unperceived objects

• For what is not “given” we need arguments

Hard and Soft DataHard and Soft Data

I mean by ‘hard’ data those which resist the solvent influence of critical reflection, and by ‘soft’ data those which, under the operation of this process, become to our minds more or less doubtful.

• Russell will attempt to sort out the hard data, which requires no argument from the soft data

• And to produce arguments in support of the ‘soft’ data of science and common sense.

• The aim is to avoid fruitless skepticism.

• Hard Data: “the facts of sense (i.e. of our own) sense-data and laws of logic

• Soft Data: persistence of unsensed objects and other minds.

Stating the ProblemStating the Problem

The Problem: Can the existence of anything other than our own hard data be inferred from the existence of those data?

• In the past the problem has not been stated in a non-question-begging way

• Wrong way of asking the question: “Can we know of the existence of any reality which is independent of ourselves?”

• This is a bad formulation because it begs the question of

– What the “self” is

• bundle of psychological states or the “bare subject” which “has” them

– How “independent” is to be understood

• logically independent or causally independent?

The SelfThe Self

• Why we cannot appeal to the “self” in posing the question

• Suppose the “self” is understood as the subject of psychological states

– The self in this sense is inferred, not immediately experienced (vide Hume!)

– Experience of the self is not hard data—and we agreed to start with hard data

• Suppose the “self” is “the whole assemblage of things that would necessarily cease to exist if our lives came to an end.”

– What are these things? Back to the question of sorting out the given

– In what sense are they “dependent” on us s.t. they’d cease to exist if our lives came to an end?

DependenceDependence

• Logical independence: it is logically possible for one thing to exist without the other

– logical possibility: conceivability, doesn’t involve a contradiction

– Russell claims one thing is logically dependent upon another only when it has the other as a part: e.g. the book is logically dependent on its pages. Is this true?

– This brings us back to the question of what the Self is.

• Causal independence: “there is no causal relation between the two such that the one only occurs as the effect of the other.”

• We can’t determine this because we’re stuck behind the Veil of Perception!

Setting the QuestionSetting the Question

The Problem: Can the existence of anything other than our own hard data be inferred from the existence of those data?

• We need to distinguish two separate questions

1. Can we know that objects of sense, or very similar objects, exist at times when we are not perceiving them?

2. If this cannot be known, can we know that other objects, inferable from objects of sense but not necessarily resembling them, exist either when we are perceiving the objects of sense or at any other time?

• We can’t answer (2) because “both the thing-in-itself of philosophy and the matter of physics present themselves as causes of sensible objects”

• Russell is offers a response to (1)

Logical Constructions and Inferred EntitiesLogical Constructions and Inferred Entities

Whenever possible, substitute constructions out of known entities for inferences to unknown entities.

Objects of a kind, F, are said to be “logical constructions” out of objects of another kind, G, if the facts about Fs reduce to facts about Gs, or everything said using the F vocabulary may be said in a more basic or fundamental way referring only to Gs.

The Average Plumber has 2.3 children.

Logical Constructions and Inferred EntitiesLogical Constructions and Inferred Entities

• The Average Plumber is a logical construction.

• There is no such being as the Average Plumber over and above regular plumbers!

• The form of the sentence “the Average Plumber has 2.3 children” is misleading: “the Average Plumber” does not refer to any individual.

• What we mean is that if we divide the number of plumbers’ children by the number of plumbers we get 2.3.

The Average Plumber

Logical Constructions and AnalysisLogical Constructions and Analysis

“The method of ‘postulating’ what we want has many advantages; they are the same as the advantages of theft over honest toil. Let us leave them to others and proceed with our honest toil.” Russell Introduction to Mathematical Philosophy

• We prefer logical constructions to (“postulated”) inferred entities in the interests of epistemic security

• We get into trouble with talk about “the average plumber” because of a mistaken understanding of language: we imagine that wherever there’s a noun or noun it must be the name of some object.

• We need to distinguish surface grammar from logical form to paraphrase away the Average Plumber and other weird non-entities

Surface Grammar vs. Logical FormSurface Grammar vs. Logical Form

• Al did the wash for Betty’s sake

• Surface grammar suggests that this sentence is about 4 things: Al, the wash, Betty…and a sake that somehow Betty has.

• But there are no such things as sakes, as the true logical form of this sentence shows

• Al did the wash in order to help Betty.

• Doping out the true logical form beneath the “surface grammar” is taken to be one of the chief projects of analytic philosophy by Russell: this is “analysis.”

Physical Objects as Logical ConstructionsPhysical Objects as Logical Constructions

• Russell is going to suggest that we understand physical objects as logical constructions out of the ‘hard data’ of sense experience.

• E.g. to say that there’s a table in front of me is to say something about the various experiences I and others have or would have: to talk about a certain structure of sensory experiences.

• There is no table over and above that structure of experiences if we understand claims about physical objects correctly

• And so we can avoid skeptical worries about the existence of objects behind the Veil of Perception!

Sense DataSense Data

• When I speak of a ‘sensible object,’ it must be understood that I do not mean such a thing as a table, which is both visible and tangible, can be seen by many people at once, and is more or less permanent. What I mean is just that patch of colour which is momentarily seen when we look at the table, or just that particular hardness which is felt when we press it, or just that particular sound which is heard when we rap it.

• Sense Data

• We need to state the external world problem without assuming an answer (i.e. “begging the question”) so we have to state it in terms of the appearances of the table

• The problem is that there are so many and they’re so different!

• Perspectival variation

• Illusion

Perspectival VariationPerspectival Variation

A table viewed from one place presents a different appearance from that which it presents from another place. This is the language of common sense, but this language already assumes that there is a real table of which we see the appearances…What we ought to say is that, while we have those muscular and other sensations which make us say we are walking, our visual sensations change in a continuous way…What is really known is a correlation of muscular and other bodily sensations with changes in visual sensations.

• This perspectival variation is supposed to show that the “sensible objects” we immediately experience are not physical objects

• Different appearances of the table are different in size and shape—the one physical object can’t have all those different properties

• Why do we privilege certain appearances as the “real” sizes or shapes of physical objects?

IllusionIllusion

We can shut one eye, or put on blue spectacles…Physiological changes also alter the appearances of things…Experience has taught us that where we see certain kinds of coloured surfaces we can, by touch, obtain certain expected sensations of hardness or softness, tactile shape, and so on…But the mere fact that we are able to infer what our tactile sensations would be shows that it is not logically necessary to assume tactile qualities before they are felt.

• Arguments from illusion too are supposed to show that the “sensible objects” we immediately experience are not physical objects

• Things don’t always appear to be as the “really are.

• Things that really aren’t appear to us in dreams, hallucinations, mirages, etc.

• Why do we privilege some appearances as veridical while dismissing illusions, dreams, etc. as non-veridical?

On Not Begging the QuestionOn Not Begging the Question

• We cannot speak legitimately of changes in the point of view and the intervening medium until we have already constructed some world more stable than that of momentary appearances.

• We cannot appeal to science—e.g. to optics and the science of perspective, to neurophysiology or physics—because science assumes that there is a world more stable than that of momentary appearances.

• Philosophy is not…

– an alternative “worldview” to the scientific or commonsensical “worldview”

– a body of doctrines that conflict with science or commonsense

The External World ProblemThe External World Problem

Can the existence of anything other than our own hard data be inferred from these data?

• The hard data of sense experience are sense data, which cannot be identified with ordinary physical objects given perspectival variation and the possibility of illusion.

• We can’t assume that our experiences are caused by concurrently existing objects outside of experience.

• We can’t appeal to the testimony of others because this assumes the existence of objects outside of our experience, viz. other minds.

• We can’t appeal to science or commonsense because we are looking for explanation and justification of scientific and commonsensical claims!

RussellRussell’’s Provisional Solutions Provisional Solution

Instead of inquiring what is the minimum of assumption by which we can explain the world of sense, we will, in order to have a model hypothesis as a help for the imagination, construct one possible (not necessary) explanation of the facts.

• The system of “perspectives”: all views of the universe, perceived and unperceived, including the private spaces of actual perceivers.

– There are as many private spaces as there are perspectives…but there is only one perspective-space, whose elements are single perspectives, each with its own private space.

• Our problem is that of constructing our common world—including physical space and its occupants—from these private perspectives, whose occupants constitute the hard data of experience.

The Penny ExampleThe Penny Example

• Private spaces are ordered by means of their similarities…we start from one which contains the appearance of a circular disk…then form a whole series of perspectives containing a graduated series of circular aspects of varying sizes.

• We can form another straight line of perspectives in which the penny is seen end-on and looks like a straight line of a certain thickness.

• These two lines will meet…where the penny is.

The penny i

s here

!

The penny i

s here

!

A Way the World Could beA Way the World Could be

• We may define ‘here’ as the place, in perspective space, which is occupied by our private world…A thing is near to ‘here’ if the place where it is near to is my private world.

• [T]wo places in perspective space are associated with every aspect of a thing…Every aspect of a thing is a member of two different classes of aspects, namely: (1) the various aspects of the thing, of which at most one appears in any given perspective; (2) the perspective of which the given aspect is a member.

• The physicist naturally classifies aspects in the first way, the psychologist in the second.

• The world we have constructed can, with a certain amount of trouble, be used to interpret the crude acts of sense, the facts of physics, and the facts of physiology. It is therefore a world which may be actual. It fits the facts, and there is no empirical evidence against it; it also is free from logical impossibilities.

What is real?What is real?

• Russell’s view may be interpreted as a version of Neutral Monism according to which what there is in the world is neither intrinsically mental nor physical—hence “neutral.

• The same things belong to two different classes: one way of classifying them is of interest to physicists; the other way to psychologists.

• ‘Real things’ are aggregates of the world’s constituents that hang together in a coherent way—a way of classifying them that’s useful for explanation and prediction. For example…

• The hypothesis that other people have minds…is a hypothesis which systematizes a vast body of facts and never leads to any consequences which there is reason to think false. There is therefore…good reason to use it as a working hypothesis.

Against SkepticismAgainst Skepticism

Our hypothesis…shows that the account of the world given by common sense and physical science can be interpreted in a way which is logically unobjectionable, and finds a place for all the data, both hard and soft. It is this hypothetical construction, with its reconciliation of psychology and physics, which is the chief outcome of our discussion.

• By understanding sense-data, the objects of direct acquaintance, as the fundamental constituents of the world we take as our starting place the ‘hard’ data of experience, which is self-evident and requires no argument.

• By eliminating “inferred entities” in favor of “logical constructions” we avoid skepticism

• And provide an account of the world that is consistent with science and common sense.

The Elephant is ConstructedThe Elephant is Constructed

The End