Kenny Anthony. Philosophy in the Modern World: A New History of Western Philosophy. Volume 4
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examination. Processes of investigation, if pushed far enough, will give one
certain solution to every question to which they can be applied. Scientists
may study a problem—e.g. that of the velocity of light—by many different
methods. They may at first obtain different results, but as each perfects his
method and his processes, the results will move steadily together towards a
destined centre. It is at that centre that truth is to be found.
Does this conflict with the thesis that reality is independent of thought?
Peirce’s answer to this is complex and subtle.
On the one hand, reality is independent, not necessarily of thought in general, but
only of what you or I or any finite number of men may think about it ...onthe
other hand, though the object of the final opinion depends on what that opinion
is, yet what that opinion is does not depend on what you or I or any man thinks.
Our perversity and that of others may indefinitely postpone the settlement of
opinion; it might even conceivably cause an arbitrary proposition to be universally
accepted as long as the human race should last. (EWP 155)
It is possible, therefore, that p should be true even though every human being
believes it to be false. Peirce offers two ways of making room for this possibility.
On the one hand, he says, another race might succeed the extinction of ours,
and the true opinion would be the one they ultimately came to. But he also
says that ‘the catholic consent that constitutes the truth is by no means to be
limited to men in this earthly life or to the human race, but extends to the
whole communion of minds to which we belong’ (EWP 60).
It is important to be clear about the content of the beliefs that we attain
in the course of this communal, unceasing pursuit of truth. Belief, Peirce
says, has three properties: first, it is something we are aware of; seco nd, it
appeases the irritation of doubt; third, it involves the establishment in our
nature of a rule of action, that is to say, a habit. Different beliefs are
distinguished by the different modes of action to which they give rise. ‘If
beliefs do not differ in this respect, if they appease the same doubt by
producing the same rule of action, then no more differences in the manner
of consciousness of them can make them differ ent beliefs.’
To illustrate this point Peirce uses a religious example. Protestants say
that after the words of consecration have been said the offerings on the
altar are bread and wine; Catholics say they are not. But members of
the two sects do not differ from each other in the expectations they have
of the sensible effects of the sacrament. ‘We can mean nothing by wine but
what has certain effects, direct or indirect, upon our senses; and to talk of
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something as having all the sensible characters of wine, yet being in reality
blood, is senseless jargon’ (EWP 146).
It is in this context that Peirce first put forward his principle of pragma-
tism, which he presents as the rule for attaining the maximum clearness
about our ideas. ‘Consider what effects, that might conceivably have prac-
tical bearings, we conceive the object of our conception to have. Then, our
conception of these effects is the whole of our conception of the object’
(EWP 146). It is important to note that Peirce’s pragmatism is a theory not of
truth, but of meaning; and as such it anticipates the verification theory of
meaning later put forward by the logical positivists. He applies the principle
to the concepts of hardness, weight, freedom, and force, and concludes, in
the latter case, ‘if we know what the effects of force are, we are acquainted
with every fact that is implied in saying that a force exists, and there is
nothing more to know’ (EWP 151).
In Peirce’s writing it is not always clear how he sees the relationship
between logic and psychology. At the beginning of his essays to illustrate
the logic of science he writes thus:
The object of reasoning is to find out, from the consideration of what we already
know, something else that we do not know. Consequently, reasoning is good if it
be such as to give a true conclusion from true premises and not otherwise. Thus
the question of its validity is purely one of fact and not of thinking. (EWP 122)
On the other hand, Peirce sometimes writes as if logical truths were laws of
mental behaviour. Thus, having told us that the three main classes of logical
inference are deduction, induction, and hypothesis, he goes on to say, ‘In
deduction the mind is under the dominion of a habit or association by virtue
of which a general idea suggests in each case a corresponding reaction’ (EWP
209). Perhaps the two statements are to be reconciled in this way: reasoning ,
whether good or bad, is a matter of habit; but it is a matter of fact, not of
thought, whether a particular piece of reasoning is valid or not.
Frege on Logic, Psychology, and Epistemology
In the writings of Frege, there is no lack of explicit discrimination between
logic and psychology. While he was writing his logicist works, from Begriffss-
chrift onwards, Frege was not interested in epistemology for its own sake, but
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he was concerned to set out the relationship between epistemology and
other related disciplines. In the tradition of Descartes, Frege believed,
epistemology had been given a fundamental role in philosophy that should
really be assigned to logic. On the other hand, philosophers in the empiricist
tradition had confused logic with psychology. In working out his logical
system Frege was anxious to show the difference in nature and role between
logic and these two other branches of study.
Frege took over, and adapted for his own purposes, Kant’s distinction
between a priori and a posteriori knowledge. To ensure that talk of a priori
knowledge involves no confusion between psychology and logic, he reminds
us that it is possible to discover the content of a proposition before we hit on a
proof of it. We must distinguish, therefore, between how we first come to
believe a proposition, and how we would eventually justify it. There must be a
justification, if we are to talk of knowledge at all, for knowledge is belief that is
both true and justified. It is absurd to talk of an a priori mistake, because one
can only know what is true.
When a proposition is called a posteriori or analytic in my sense, this is not a
judgement about the conditions, psychological, physiological and physical,
which have made it possible to represent the content of the proposition in
consciousness. Nor is it a judgement about the possibly defective method by
which some other person has come to believe it true. Rather, it is a judgement
about the fundamental ground which provides the justification for believing it to
be true. (FA 3)
If the proposition is a mathematical one, its justification must be mathe-
matical; it cannot be a psychological matter of processes in the mathe-
matician’s mind. To be sure, mathematicians have sensations and mental
images, and these may play a part in the thoughts of someone who is
calculating. But these images and thoughts are not what arithmetic is
about. Different mathematicians associate different images with the same
number: in operating with the number one hundred, one person may
think of ‘100’ and another of ‘C’. Even if psychology could give a causal
explanation of the occurrence of the thought that ten squared is one
hundred, it would still be totally different from arithmetic, for arithmetic is
concerned with the truth of such propositions, psychology with their
occurrence in thought. A proposition may be thought of without being
true, and a proposition may be true without being thought of.
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Psychology is interested in the cause of our thinking, mathematics in the
proof of our thoughts. Cause and proof are quite different things. Without
an appropriate ration of phosphorus in his brain, no doubt, Pythagoras
would have been unable to prove his famous theorem; but that does not
mean that a statement of the phosphorus content of his brain should occur
as a line in the proof. If humans have evolved, no doubt there has been
evolution in human consciousness; so if mathematics was a matter of
sensations and ideas, we would need to warn astronomers against drawing
conclusions about events in the distant past. Frege brings out the absurdity
of this position in an ironic passage:
You reckon that 2 2 ¼ 4; but the idea of number has a history, an evolution. It
may be doubted whether it had yet progressed so far. How do you know that in
that distant past that proposition already existed? Might not the creatures then
alive have held the proposition 2 2 ¼ 5? Perhaps it was only later that natural
selection, in the struggle for existence, evolved the proposition 2 2 ¼ 4, and
perhaps that in its turn is destined to develop into 2 2 ¼ 3. (FA, pp. vi–vii)
Throughout his life, Frege continued to maintain a sharp distinction
between logic and psychology. In his late essay ‘Thoughts’ he warned
against the ambiguity inherent in the statement that logic deals with the
laws of thought. If, by ‘laws of thought’, we mean psychological laws that
relate mental events to their causes, then they are not laws of logic because
they would make no distinction between true and false thoughts, since
error and superstition have causes no less than sound belief . Logical laws
are ‘laws of thought’ only in the same sense as moral laws are laws of
behaviour. Actual thinking does not always obey the laws of logic any more
than actual behaviour always obeys the moral law.
However, in his late ‘Thoughts’ Frege ventures into epistemology in a
manner that tends to blur the distinctions he had so resolutely defended. He
inquires about the sense, or mode of presentation, of the first-person pronoun
‘I’, which he treats as a proper name that has its user as its reference. Everyone,
Frege says, ‘is presented to himself in a special and primary way, in which he is
presented to no one else’. Suppose that Horatio has the thought that he has
been wounded. Only he can grasp the sense of that thought, since it is only to
himself that he is presented in this special way.
He cannot communicate a thought he alone can grasp. Therefore, if he now says
‘I have been wounded’ he must use ‘I’ in a sense which can be grasped by others,
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perhaps in the sense of ‘the person who is now speaking to you’. In doing so he makes
the circumstances of his utterance serve the expression of the thought. (CP 360)
This seems to contradict Frege’s hitherto consistent claim that whereas
mental images might be private, thoughts were the common property of
us all. On his own principles an incommunicable thought about a private
ego would not be a thought at all. But instead of rejecting the idea that ‘I’ is a
proper name and discarding the whole notion of the Cartesian ego, Frege
went on to present in highly Cartesian terms a full-blown doctrine of two
separate worlds, one interior and private and the other exterior and public.
Perceptible things of the physical world, he said, are accessible to us all: we
can all see the same houses and touch the same trees. But in addition, he
claimed, there is an inner world of sense-impressions, images and feelings, of
desires and wishes—items which, for present purposes, we may call ‘ideas’.
Anyone who maintains, as Frege did in this essay, that our mental life
takes place within an inner private world must at some time face the
question: what reason is there for believing that there is any such thing as
an outer world? Descartes, in his Meditations, used sceptical arguments to
purify the reader, temporarily, from belief in anything beyond the private
realm; he then endeavoured to restore the reader’s faith in the external
world by appealing to the truthfulness of God. Frege here accepts the
Cartesian distinction between matter (the world of things) and mind (the
world of ideas). Like Descartes, he accepted the need to provide an answer
to idealist scepticism, the thesis that nothing exists except ideas.
What if everything were only a dream, a play performed upon the stage
of my consciousness (CP 363)? I seem to be walking in a green field with a
companion; but perhaps the realm of things is empty, and all I have is ideas
of which I myself am the owner. If only what is my idea can be the object of
my awareness, then for all I know there is no green field (for a field is not
an idea, and there are no green ideas) and no companion (for human
beings are not ideas). For all I know there are not even any ideas other than
my own (for I can know of no one else to own them). Frege concludes:
‘Either the thesis that only what is my idea can be the object of my
awareness is false, or all my knowledge and perception is restricted to
the range of my ideas, to the stage of my self-consciousness. In this case
I should have only a n inner world and I should know nothing of other
people’ (CP 364). Indeed, does not this train of sceptical reasoning lead to
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the conclusion that I am myself an idea? Lying in a deckchair, I have a range
of visual impressions, from the toes of my shoes to the blurred outline of
my nose. By what right do I pick out one of my ideas and set it up as owner
of the others? Why have an owner for ideas at all?
Here we come to a full stop. If there is no owner of ideas, there are no
ideas either; there cannot be an experience without someone to experience.
A pain is necessarily felt, and what is felt must have someone feeling it. If so,
there is something that is not yet my idea, and yet can be an object of my
thought, namely myself. Frege, like Descartes, brings scepticism to an end
with a cogito, ergo sum. But whereas Descartes’s ego was a non-ideal subject of
thinking, Frege’s ego is a non-ideal object of thought. Its existence refutes
the thesis that only what is part of the content of my consciousness can be
the object of my thought.
If there is to be such a thing as science, Frege maintained, ‘a third realm
must be recognized’—a world in addition to the world of things and the
world of ideas. The ego, as the owner of ideas, is the first citizen of this third
realm. The third realm is the realm of objective thought. The denizens of
this realm share with ideas the property of being imperceptible by the
senses, and share with physical objects the property of being independent
of an owner. Pythagoras’ theorem is timelessly true and needs no owner; it
does not begin to be true when it is first thought of or proved (CP 362).
Other people, Frege says, can grasp thoughts no less than I; we are
not owners of our thoughts as we are owners of our ideas. We do not
have thoughts; thoughts are what we grasp. What is grasped is already there
and all we do is take possession of it. Our grasping a thought has no more
effect on the thought itself than our observing it affects the new moon.
Thoughts do not change or come and go; they are not causally active or
passive in the way in which objects are in the physical world. In that world,
one thing acts on another and changes it; it is itself acted upon and itself
changes. This is not so in the timeless world that Pythagoras’ theorem
inhabits (PW 138).
Few who have followed Frege down the path of Cartesian scepticism will
follow him in the route he offers out of the maze. His response to the
challenge is no more convincing than Descartes’s own. Both philosophers,
having accepted a division between a public world of physical things and a
private world of human consciousness, seek to rejoin what they have
separated by appealing to a third world: the divine mind in the case of
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Descartes, and the world of thoughts in the case of Frege. In each case the
fatal mistake was the acceptance of the initial dichotomy. There are not
two worlds, but a single one to which there belong not just inert physical
objects but also conscious rational animals. Frege was wrong, and sinned
against his own cardinal principle of separating thoughts from ideas, in
accepting that consciousness provides us with incommunicable contents
and unshareable certainties.
Knowledge by Acquaintance and Knowledge by Description
Six years before Frege published his articles on the nature of thought,
Bertrand Russell had written his brief Problems of Philosophy, a book that was
to give many generations of philosophy students their first introduction to
epistemology. Russell was a godson of John Stuart Mill, and for a great part of
his life he endeavoured to be faithful to the British empiricist tradition of
which Mill had been such an intrepid exponent. But Russell could not accept
Mill’s view of mathematics as an empirical science, and so his empiricism was
always blended with an element of the Platonism that he shared with Frege.
His starting point in Problems is the systematic doubt of Descartes.
It seems to me that I am now sitting in a chair, at a table of a certain shape, on
which I see sheets of paper with writing or print. By turning my head I see out of
the window buildings and clouds and the sun. I believe that the sun is about
ninety-three million miles from the earth; that it is a hot globe many times bigger
than the earth; that, owing to the earth’s rotation, it rises every morning, and will
continue to do so for an indefinite time in the future. (PP 7–8)
However evident this seems, Russell tells us, it may all be reasonably
doubted. The table looks different and feels different from different angles
and to different people in different circumstances. The real table is not
what we immediately experience, but is an inference from what is imme-
diately known. What is immediate ly known in sensation is something quite
different from any real table.
Let us give the name of ‘sense data’ to the things that are immediately known in
sensation: such things as colours, sounds, smells, hardnesses, roughnesses, and so
on. We shall give the name ‘sensation’ to the experience of being immediately
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aware of these things. Thus, whenever we see a colour, we have a sensation of the
colour, but the colour itself is a sense-datum, not a sensation. The colour is that
of which we are immediately aware, and the awareness itself is the sensation. (PP 12)
Sense-data are the only things of which we can be really certain. Descartes
brought his own doubt to an end with the cogito, ‘I think, therefore I am’. But
this, Russell warns us, says something more than what is certain: sense-data
bring no assurance of an abiding self, and what is really certain is not ‘I am
seeing a brown colour’ but ‘a brown colour is being seen’. Sense-data are
private and personal: is there any reason to believe in public neutral objects
such as we imagine tables to be? If there is not, then a fortiori there is no
reason to believe in persons other than myself, since it is only through their
bodies that I have any access to others’ minds.
Russell concedes that there is no actual proof that the whole of life is not
just a dream. Our belief in an independent external world is instinctive
rather than reflective, but this does not mean that there is any good reason
to reject it. If we agree provisionally that there are physical objects as well
as sense-data, should we say that these objects are the causes of the sense-
data? If we do, we must immediately add that there is no reason to think
that these causes are like sense-dat a—e.g. that they are coloured. Common
sense leaves us quite in the dark about their true nature.
In order to clarify the relationship between sense-data and the objects
that cause them, Russell introd uces his celebrated distinction between
knowledge by acquaintance and knowledge by description.
We shall say that we have acquaintance with anything of which we are directly aware,
without the intermediary of any process of inference or any knowledge of truths.
Thus in the presence of my table I am acquainted with the sense-data that make up
the appearance of my table—its colour, shape, hardness, smoothness, etc....My
knowledge of the table as a physical object, on the contrary, is not direct knowledge.
Such as it is, it is obtained through acquaintance with the sense-data that make up
the appearance of the table. We have seen that it is possible, without absurdity, to
doubt whether there is a table at all, whereas it is not possible to doubt the sense-
data. My knowledge of the table is of the kind which we shall call ‘knowledge
by description’. The table is ‘the physical object which causes such-and-such sense-
data’. This describes the table by means of the sense-data. (PP 46–7)
Sense-data are not the only things with which we have acquaintance.
Introspection gives us acquaintance with our own thoughts, feelings, and
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desires. Memory gives us acquaintance with past data of the inner or outer
senses. We may even, though this is a matter of doubt, have acquaintance
with our own selves. We do not have acquaintance with physical objects or
other minds. But we do have acquaintance with rather more rarefied
entities: namely, universal concepts, such as whiteness, brotherhood, and so on.
Like Plato, Russell thought that universals belonged to a supra-sensible
world, the world of being. The world of being was unchangeable, rigid,
perfect, and dead. It was the world of existence that contained thoughts,
feelings, and sense-data. By temperament some people preferred one
world, and others preferred the other. But ‘both are real, and both are
important to the metaphysician’ (PP 100).
Every proposition that we can understand, Russell maintained, must be
composed wholly of constituents with which we are acquainted. How then
can we make statements about Bismarck, whom we have never seen, or
Europe, which is far too big to be taken in by a sense-datum? Russell’s answer
is that any judgement about Bismarck or Europe really contains a nested
series of definite descriptions, and all knowledge about them is ultimately
reducible to knowledge of what is known by acquaintance. Only in this way
can we have any knowledge of things that we have never experienced.
When he came to write Our Knowledge of the External World (1914) Russell
described the relationship between physical objects and sense-data by
saying that the former were logical constructions out of the latter. Whereas
in Problems he though that objects caused sense-data, but were distinct
from them, he now came to believe that statements about the objects of
everyday life, and scientific statements also, were reducible by analysis into
statements about sensory experiences. But this too turned out to be a
temporary phase in his thinking, and in his last philosophical work, Human
Knowledge: Its Scope and Limits (1948), he returned to a causal theory of
perception. In the meantime much had happened to call in question the
whole basis and method of his epistemology.
Husserl’s Epoche
Husserl was the last great philosopher in the Cartesian tradition. He saw
the phenomenological reduction, and in particular the programme of
epoche, or suspension of judgement about the existence of extra-mental
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reality, as a refinement of Descartes’s methodological doubt. In several
ways he sought to be more radical than Descartes in cutting away from the
foundations of philosophy whatever it is possible to doubt. First of all, he
denied the indubitability of the cogito if that is supposed to affirm the
existence of an enduring self rather than just the subject of my present
sensations. Second, he thought that Descartes took the data of conscious-
ness at their face value, without distinguishing within them between what
was actually given in sensation, and what in them was the result of a
metaphysical interpretation that tacitly presupposed the existence of an
external world, spread out in space and time and subject to a principle of
causality (LI 16).
The differences that separate Husserl from Descartes are, however,
unimportant in comparison with the similarities that bind the two
together. Both philosophers saw epistemology as the basic discipline,
which is prior to all other parts of philosophy and to all empirical sciences.
Husserl, like Descartes, never doubted two things : the certainty of his own
mental states and processes, and the language that he uses to report these
phenomena. These certainties, they both believe, can survive any doubt
about the external world.
Descartes believed that God could have created my mind, just as it is,
without there being any such thing as matter. Husserl argued that our
awareness of external objects consists in our partial glimpses and contacts
with them—our ‘adumbrations’ of them, as he puts it. But unless these
adumbrations exhibited the order they do, we could not in any way
construct objects out of them. However, it is perfectly conceivable that
this order might be shattered, leaving only a chaotic series of sensations.
If so, we would cease to perceive physical objects, and our world would
be destroyed. But consciousness, Husserl argued, would survive such a
destruction of the world (Ideas, 49).
If my own consciousness is indubitably certain, while the world of
matter is essentially dubious, nothing could seem more judicious than to
suspend judgement about the latter while concentrating on the accurate
description and analysis of the former. But Husserl’s epoche, or suspension of
judgement, is not the neutral starting point that it appears to be between
realism and idealism. For the assumption that consciousness can be given
expression in a purely private world begs the question against realism from
the start. Because they separate the content of consciousness from any
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