--- is an example by Grice in "Way in the Way of Words" -- his argument against Malcolm.
Let us reconsider what we mean, 'infinity', or
"∞"
or
"ℵ" (aleph).
We can start with the excellent job done by R. B. Jones at
where Locke's Essay is converted to HTML for RBJones.com by first edition 1994/10/29 last
modified 2009/3/30.
Chapter XVII
modified 2009/3/30.
Chapter XVII
"Of Infinity"
Locke writes:
space, duration, and number."
"He that would know what kind of idea it is to which we give the name of
"infinity", cannot do it better than by considering to what infinity is by the
mind more immediately attributed."
"And then we cannot do it better than by considering how the mind comes to frame it."
""Finite" and "infinite" seem to me to be looked upon by the mind as the modes
of quantity, and to be attributed primarily in their first designation only
to those things which have parts, and are capable of increase or
diminution by the addition or subtraction of any the least part."
"And such are the ideas of space, duration, and number, which we have
considered in the foregoing chapters."
"It is true, that we cannot but be assured, that the great God, of whom and
from whom are all things, is incomprehensibly infinite."
"But yet, when we apply to that first and supreme Being our idea of
"infinite", in our weak and narrow thoughts, we do it primarily in respect to his
duration and ubiquity."
"And, I think, more figuratively to his power, wisdom, and goodness, and
other attributes, which are properly inexhaustible and incomprehensible, &c."
"For, when we call them "infinite", we have no other idea of this infinity
but what carries with it some reflection on, and imitation of, that number or
extent of the acts or objects of God's power, wisdom, and goodness, which
can never be supposed so great, or so many, which these attributes will not
always surmount and exceed, let us multiply them in our thoughts as far as
we can, with all the infinity of endless number."
"I do not pretend to say
how these attributes are in God, who is infinitely beyond the reach of our
narrow capacities."
"They do, without doubt, contain in them all possible
perfection."
"But this, I say, is our way of conceiving them, and these our ideas
of their infinity."
"The idea of "finite" is easily got."
"Finite then, and infinite, being by the
mind looked on as modifications of expansion and duration, the next thing to
be considered, is,- How the mind comes by them.
As for the idea of finite,
there is no great difficulty.
The obvious portions of extension that affect
our senses, carry with them into the mind the idea of finite: and the
ordinary periods of succession, whereby we measure time and duration, as hours,
days, and years, are bounded lengths.
The difficulty is, how we come by
those boundless ideas of eternity and immensity; since the objects we converse
with come so much short of any approach or proportion to that largeness."
"How we come by the idea of infinity.
Every one that has any idea of any
stated lengths of space, as a foot, finds that he can repeat that idea; and
joining it to the former, make the idea of two feet.
And by the addition of
a third, three feet; and so on, without ever coming to an end of his
additions, whether of the same idea of a foot, or, if he pleases, of doubling it,
or any other idea he has of any length, as a mile, or diameter of the
earth, or of the orbis magnus.
For whichever of these he takes, and how often
soever he doubles, or any otherwise multiplies it, he finds, that, after he
has continued his doubling in his thoughts, and enlarged his idea as much
as he pleases, he has no more reason to stop, nor is one jot nearer the end
of such addition, than he was at first setting out: the power of enlarging
his idea of space by further additions remaining still the same, he hence
takes the idea of infinite space."
"For let us consider our idea of space as boundless."
"This, I think, is the way whereby the mind gets the idea of infinite
space.
It is a quite different consideration, to examine whether the mind has
the idea of such a boundless space actually existing; since our ideas are not
always proofs of the existence of things: but yet, since this comes here
in our way, I suppose I may say, that we are apt to think that space in
itself is actually boundless, to which imagination the idea of space or
expansion of itself naturally leads us.
For, it being considered by us, either as
the extension of body, or as existing by itself, without any solid matter
taking it up, (for of such a void space we have not only the idea, but I
have proved, as I think, from the motion of body, its necessary existence), it
is impossible the mind should be ever able to find or suppose any end of
it, or be stopped anywhere in its progress in this space, how far soever it
extends its thoughts.
Any bounds made with body, even adamantine walls, are
so far from putting a stop to the mind in its further progress in space
and extension that it rather facilitates and enlarges it.
For so far as that
body reaches, so far no one can doubt of extension; and when we are come to
the utmost extremity of body, what is there that can there put a stop, and
satisfy the mind that it is at the end of space, when it perceives that it
is not; nay, when it is satisfied that body itself can move into it?
For,
if it be necessary for the motion of body, that there should be an empty
space, though ever so little, here amongst bodies; and if it be possible for
body to move in or through that empty space;- nay, it is impossible for any
particle of matter to move but into an empty space; the same possibility
of a body's moving into a void space, beyond the utmost bounds of body, as
well as into a void space interspersed amongst bodies, will always remain
clear and evident: the idea of empty pure space, whether within or beyond the
confines of all bodies, being exactly the same, differing not in nature,
though in bulk; and there being nothing to hinder body from moving into it.
So that wherever the mind places itself by any thought, either amongst, or
remote from all bodies, it can, in this uniform idea of space, nowhere find
any bounds, any end; and so must necessarily conclude it, by the very
nature and idea of each part of it, to be actually infinite."
"And so of duration."
"As, by the power we find in ourselves of repeating, as often as we will,
any idea of space, we get the idea of immensity; so, by being able to repeat
the idea of any length of duration we have in our minds, with all the
endless addition of number, we come by the idea of eternity.
For we find in
ourselves, we can no more come to an end of such repeated ideas than we can
come to the end of number; which every one perceives he cannot.
But here
again it is another question, quite different from our having an idea of
eternity, to know whether there were any real being, whose duration has been
eternal.
And as to this, I say, he that considers something now existing, must
necessarily come to Something eternal.
But having spoke of this in another
place, I shall say here no more of it, but proceed on to some other
considerations of our idea of infinity."
"Why other ideas are not capable of infinity."
"If it be so, that our idea of infinity be got from the power we observe in
ourselves of repeating, without end, our own ideas, it may be demanded,-
Why we do not attribute infinity to other ideas, as well as those of space
and duration."
"Since they may be as easily, and as often, repeated in our minds as the
other: and yet nobody ever thinks of infinite sweetness, or infinite
whiteness, though he can repeat the idea of sweet or white, as frequently as those
of a yard or a day?
"To which I answer as follows.
All the ideas that are considered as having parts, and
are capable of increase by the addition of any equal or less parts, afford
us, by their repetition, the idea of infinity; because, with this endless
repetition, there is continued an enlargement of which there can be no end.
But in other ideas it is not so.
For to the largest idea of extension or
duration that I at present have, the addition of any the least part makes an
increase; but to the perfectest idea I have of the whitest whiteness, if I
add another of a less or equal whiteness, (and of a whiter than I have, I
cannot add the idea), it makes no increase, and enlarges not my idea at
all; and therefore the different ideas of whiteness, &c. are called degrees."
"For those ideas that consist of parts are capable of being augmented by
every addition of the least part; but if you take the idea of white, which
one parcel of snow yielded yesterday to our sight, and another idea of white
from another parcel of snow you see to-day, and put them together in your
mind, they embody, as it were, and run into one, and the idea of whiteness
is not at all increased; and if we add a less degree of whiteness to a
greater, we are so far from increasing, that we diminish it.
Those ideas that
consist not of parts cannot be augmented to what proportion men please, or be
stretched beyond what they have received by their senses; but space,
duration, and number, being capable of increase by repetition, leave in the mind
an idea of endless room for more; nor can we conceive anywhere a stop to a
further addition or progression: and so those ideas alone lead our minds
towards the thought of infinity."
"There is a Difference between infinity of space, and space infinite."
"Though our idea of infinity arise from the contemplation of quantity, and
the endless increase the mind is able to make in quantity, by the repeated
additions of what portions thereof it pleases; yet I guess we cause great
confusion in our thoughts, when we join infinity to any supposed idea of
quantity the mind can be thought to have, and so discourse or reason about an
infinite quantity, as an infinite space, or an infinite duration.
For, as
our idea of infinity being, as I think, an endless growing idea, but the
idea of any quantity the mind has, being at that time terminated in that idea,
(for be it as great as it will, it can be no greater than it is,)- to join
infinity to it, is to adjust a standing measure to a growing bulk; and
therefore I think it is not an insignificant subtilty, if I say, that we are
carefully to distinguish between the idea of the infinity of space, and the
idea of a space infinite.
The first is nothing but a supposed endless
progression of the mind, over what repeated ideas of space it pleases; but to
have actually in the mind the idea of a space infinite, is to suppose the
mind already passed over, and actually to have a view of all those repeated
ideas of space which an endless repetition can never totally represent to it;
which carries in it a plain contradiction.
"We have NO idea of infinite space."
"This, perhaps, will be a little plainer, if we consider it in numbers."
-------------------------
"The infinity of numbers, to the end of whose addition every one perceives
there is no approach, easily appears to any one that reflects on it."
"But, how clear soever this idea of the infinity of number be, there is
nothing yet more evident than the absurdity of the actual idea of an infinite
number."
"Whatsoever positive ideas we have in our minds of any space, duration, or
number, let them be ever so great, they are still finite."
"But when we suppose an inexhaustible remainder, from which we remove all
bounds, and wherein we allow the mind an endless progression of thought,
without ever completing the idea, there we have our idea of infinity: which,
though it seems to be pretty clear when we consider nothing else in it but
the negation of an end, yet, when we would frame in our minds the idea of an
infinite space or duration, that idea is very obscure and confused,
because it is made up of two parts, very different, if not inconsistent."
"For, let a man frame in his mind an idea of any space or number, as great
as he will; it is plain the mind rests and terminates in that idea, which
is contrary to the idea of infinity, which consists in a supposed endless
progression.
And therefore I think it is that we are so easily confounded,
when we come to argue and reason about infinite space or duration, &c.
Because the parts of such an idea not being perceived to be, as they are,
inconsistent, the one side or other always perplexes, whatever consequences we
draw from the other; as an idea of motion not passing on would perplex any one
who should argue from such an idea, which is not better than an idea of
motion at rest.
And such another seems to me to be the idea of a space, or
(which is the same thing) a number infinite, i.e. of a space or number which
the mind actually has, and so views and terminates in; and of a space or
number, which, in a constant and endless enlarging and progression, it can in
thought never attain to.
For, how large soever an idea of space I have in
my mind, it is no larger than it is that instant that I have it, though I
be capable the next instant to double it, and so on in infinitum; for that
alone is infinite which has no bounds; and that the idea of infinity, in
which our thoughts can find none."
"Number affords us the clearest idea of infinity.
But of all other ideas,
it is number, as I have said, which I think furnishes us with the clearest
and most distinct idea of infinity we are capable of.
For, even in space and
duration, when the mind pursues the idea of infinity, it there makes use
of the ideas and repetitions of numbers, as of millions and millions of
miles, or years, which are so many distinct ideas,- kept best by number from
running into a confused heap, wherein the mind loses itself; and when it has
added together as many millions, &c., as it pleases, of known lengths of
space or duration, the clearest idea it can get of infinity, is the confused
incomprehensible remainder of endless addible numbers, which affords no
prospect of stop or boundary."
"Our different conceptions of the infinity of number can be contrasted with those
of duration and expansion.
It will, perhaps, give us a little further light
into the idea we have of infinity, and discover to us, that it is nothing
but the infinity of number applied to determinate parts, of which we have
in our minds the distinct ideas, if we consider that number is not generally
thought by us infinite, whereas duration and extension are apt to be so;
which arises from hence,- that in number we are at one end, as it were: for
there being in number nothing less than an unit, we there stop, and are at
an end; but in addition, or increase of number, we can set no bounds: and
so it is like a line, whereof one end terminating with us, the other is
extended still forwards, beyond all that we can conceive. But in space and
duration it is otherwise.
For in duration we consider it as if this line of
number were extended both ways- to an unconceivable, undeterminate, and
infinite length; which is evident to any one that will but reflect on what
consideration he hath of Eternity; which, I suppose, will find to be nothing else
but the turning this infinity of number both ways, a parte ante, and a
parte post, as they speak.
For, when we would consider eternity, a parte ante,
what do we but, beginning from ourselves and the present time we are in,
repeat in our minds the ideas of years, or ages, or any other assignable
portion of duration past, with a prospect of proceeding in such addition with
all the infinity of number: and when we would consider eternity, a parte
post, we just after the same rate begin from ourselves, and reckon by
multiplied periods yet to come, still extending that line of number as before.
And
these two being put together, are that infinite duration we call Eternity:
which, as we turn our view either way, forwards or backwards, appears
infinite, because we still turn that way the infinite end of number, i.e. the
power still of adding more.
"How we conceive the infinity of space.
The same happens also in space,
wherein, conceiving ourselves to be, as it were, in the centre, we do on all
sides pursue those indeterminable lines of number; and reckoning any way
from ourselves, a yard, mile, diameter of the earth, or orbis magnus,- by the
infinity of number, we add others to them, as often as we will.
And having
no more reason to set bounds to those repeated ideas than we have to set
bounds to number, we have that indeterminable idea of immensity."
"Let us speak of Infinite divisibility."
"And since in any bulk of matter our thoughts can never arrive at the
utmost divisibility, therefore there is an apparent infinity to us also in that,
which has the infinity also of number; but with this difference,- that, in
the former considerations of the infinity of space and duration, we only
use addition of numbers; whereas this is like the division of an unit into
its fractions, wherein the mind also can proceed in infinitum, as well as in
the former additions; it being indeed but the addition still of new
numbers: though in the addition of the one, we can have no more the positive idea
of a space infinitely great, than, in the division of the other, we can
have the [positive] idea of a body infinitely little;- our idea of infinity
being, as I may say, a growing or fugitive idea, still in a boundless
progression, that can stop nowhere."
"There is No positive idea of infinity."
"Though it be hard, I think, to find anyone so absurd as to say he has the
positive idea of an actual infinite number;- the infinity whereof lies only
in a power still of adding any combination of units to any former number,
and that as long and as much as one will; the like also being in the
infinity of space and duration, which power leaves always to the mind room for
endless additions;- yet there be those who imagine they have positive ideas
of infinite duration and space.
It would, I think, be enough to destroy any
such positive idea of infinite, to ask him that has it,- whether he could
add to it or no; which would easily show the mistake of such a positive
idea.
We can, I think, have no positive idea of any space or duration which is
not made up of, and commensurate to, repeated numbers of feet or yards, or
days and years; which are the common measures, whereof we have the ideas in
our minds, and whereby we judge of the greatness of this sort of
quantities.
And therefore, since an infinite idea of space or duration must needs be
made up of infinite parts, it can have no other infinity than that of
number capable still of further addition; but not an actual positive idea of a
number infinite.
For, I think it is evident, that the addition of finite
things together (as are all lengths whereof we have the positive ideas) can
never otherwise produce the idea of infinite than as number does; which,
consisting of additions of finite units one to another, suggests the idea of
infinite, only by a power we find we have of still increasing the sum, and
adding more of the same kind; without coming one jot nearer the end of such
progression."
"Let us show how we cannot have a positive idea of infinity in quantity."
"They who would prove their idea of infinite to be positive, seem to me to
do it by a pleasant argument, taken from the negation of an end; which
being negative, the negation of it is positive.
He that considers that the end
is, in body, but the extremity or superficies of that body, will not
perhaps be forward to grant that the end is a bare negative: and he that
perceives the end of his pen is black or white, will be apt to think that the end
is something more than a pure negation.
Nor is it, when applied to duration,
the bare negation of existence, but more properly the last moment of it.
But if they will have the end to be nothing but the bare negation of
existence, I am sure they cannot deny but the beginning is the first instant of
being, and is not by any body conceived to be a bare negation; and therefore,
by their own argument, the idea of eternal, a parte ante, or of a duration
without a beginning, is but a negative idea."
"Let us consider what is positive, what negative, in our idea of infinite."
"The idea of infinite has, I confess, something of positive in all those
things we apply to it."
"When we would think of infinite space or duration, we at first step
usually make some very large idea, as perhaps of millions of ages, or miles,
which possibly we double and multiply several times.
All that we thus amass
together in our thoughts is positive, and the assemblage of a great number of
positive ideas of space or duration.
But what still remains beyond this we
have no more a positive distinct notion of than a mariner has of the depth
of the sea; where, having let down a large portion of his sounding-line, he
reaches no bottom.
Whereby he knows the depth to be so many fathoms, and
more; but how much the more is, he hath no distinct notion at all: and could
he always supply new line, and find the plummet always sink, without ever
stopping, he would be something in the posture of the mind reaching after a
complete and positive idea of infinity.
In which case, let this line be
ten, or ten thousand fathoms long, it equally discovers what is beyond it,
and gives only this confused and comparative idea, that this is not all, but
one may yet go farther.
So much as the mind comprehends of any space, it
has a positive idea of: but in endeavouring to make it infinite,- it being
always enlarging, always advancing,- the idea is still imperfect and
incomplete.
So much space as the mind takes a view of in its contemplation of
greatness, is a clear picture, and positive in the understanding: but infinite
is still greater. 1.
Then the idea of so much is positive and clear. 2.
The
idea of greater is also clear; but it is but a comparative idea, the idea
of so much greater as cannot be comprehended. 3.
And this is plainly
negative: not positive.
For he has no positive clear idea of the largeness of any
extension, (which is that sought for in the idea of infinite), that has not
a comprehensive idea of the dimensions of it: and such, nobody, I think,
pretends to in what is infinite.
For to say a man has a positive clear idea
of any quantity, without knowing how great it is, is as reasonable as to
say, he has the positive clear idea of the number of the sands on the
sea-shore, who knows not how many there be, but only that they are more than
twenty.
For just such a perfect and positive idea has he of an infinite space or
duration, who says it is larger than the extent or duration of ten, one
hundred, one thousand, or any other number of miles, or years, whereof he has
or can have a positive idea; which is all the idea, I think, we have of
infinite.
So that what lies beyond our positive idea towards infinity, lies in
obscurity, and has the indeterminate confusion of a negative idea, wherein
I know I neither do nor can comprehend all I would, it being too large for
a finite and narrow capacity.
And that cannot but be very far from a
positive complete idea, wherein the greatest part of what I would comprehend is
left out, under the undeterminate intimation of being still greater.
For to
say, that, having in any quantity measured so much, or gone so far, you
are not yet at the end, is only to say that that quantity is greater.
So that
the negation of an end in any quantity is, in other words, only to say
that it is bigger; and a total negation of an end is but carrying this bigger
still with you, in all the progressions of your thoughts shall make in
quantity; and adding this idea of still greater to all the ideas you have, or
can be supposed to have, of quantity.
Now, whether such an idea as that be
positive, I leave any one to consider."
"We have no positive idea of an infinite duration.
I ask those who say they
have a positive idea of eternity, whether their idea of duration includes
in it succession, or not?
If it does not, they ought to show the difference
of their notion of duration, when applied to an eternal Being, and to a
finite; since, perhaps, there may be others as well as I, who will own to
them their weakness of understanding in this point, and acknowledge that the
notion they have of duration forces them to conceive, that whatever has
duration, is of a longer continuance to-day than it was yesterday.
If, to avoid
succession in external existence, they return to the punctum stans of the
schools, I suppose they will thereby very little mend the matter, or help
us to a more clear and positive idea of infinite duration; there being
nothing more inconceivable to me than duration without succession.
Besides, that
punctum stans, if it signify anything, being not quantum, finite or
infinite cannot belong to it.
But, if our weak apprehensions cannot separate
succession from any duration whatsoever, our idea of eternity can be nothing
but of infinite succession of moments of duration wherein anything does
exist; and whether any one has, or can have, a positive idea of an actual
infinite number, I leave him to consider, till his infinite number be so great
that he himself can add no more to it; and as long as he can increase it, I
doubt he himself will think the idea he hath of it a little too scanty for
positive infinity."
"No complete idea of eternal being.
I think it unavoidable for every
considering, rational creature, that will but examine his own or any other
existence, to have the notion of an eternal, wise Being, who had no beginning:
and such an idea of infinite duration I am sure I have.
But this negation of
a beginning, being but the negation of a positive thing, scarce gives me a
positive idea of infinity; which, whenever I endeavour to extend my
thoughts to, I confess myself at a loss, and I find I cannot attain any clear
comprehension of it."
"There is No positive idea of infinite space."
"He that thinks he has a positive idea of infinite space, will, when he
considers it, find that he can no more have a positive idea of the greatest,
than he has of the least space.
For in this latter, which seems the easier
of the two, and more within our comprehension, we are capable only of a
comparative idea of smallness, which will always be less than any one whereof
we have the positive idea.
All our positive ideas of any quantity, whether
great or little, have always bounds, though our comparative idea, whereby we
can always add to the one, and take from the other, hath no bounds.
For
that which remains, either great or little, not being comprehended in that
positive idea which we have, lies in obscurity; and we have no other idea of
it, but of the power of enlarging the one and diminishing the other,
without ceasing.
A pestle and mortar will as soon bring any particle of matter to
indivisibility, as the acutest thought of a mathematician; and a surveyor
may as soon with his chain measure out infinite space, as a philosopher by
the quickest flight of mind reach it, or by thinking comprehend it; which
is to have a positive idea of it.
He that thinks on a cube of an inch
diameter, has a clear and positive idea of it in his mind, and so can frame one
of 1/2, 1/4, 1/8, and so on, till he has the idea in his thoughts of
something very little; but yet reaches not the idea of that incomprehensible
littleness which division can produce.
What remains of smallness is as far from
his thoughts as when he first began; and therefore he never comes at all to
have a clear and positive idea of that smallness which is consequent to
infinite divisibility."
"What is positive, what negative, in our idea of infinite.
Every one that
looks towards infinity does, as I have said, at first glance make some very
large idea of that which he applies it to, let it be space or duration; and
possibly he wearies his thoughts, by multiplying in his mind that first
large idea: but yet by that he comes no nearer to the having a positive clear
idea of what remains to make up a positive infinite, than the country
fellow had of the water which was yet to come, and pass the channel of the
river where he stood."
Rusticus expectat dum defluat amnis, at ille
Labitur, et labetur in omne volubilis oevum.
"Some think they have a positive idea of eternity, and not of infinite
space."
"There are some I have met that put so much difference between infinite
duration and infinite space, that they persuade themselves that they have a
positive idea of eternity, but that they have not, nor can have any idea of
infinite space.
The reason of which mistake I suppose to be this- that
finding, by a due contemplation of causes and effects, that it is necessary to
admit some Eternal Being, and so to consider the real existence of that
Being as taken up and commensurate to their idea of eternity; but, on the other
side, not finding it necessary, but, on the contrary, apparently absurd,
that body should be infinite, they forwardly conclude that they can have no
idea of infinite space, because they can have no idea of infinite matter.
Which consequence, I conceive, is very ill collected, because the existence
of matter is no ways necessary to the existence of space, no more than the
existence of motion, or the sun, is necessary to duration, though duration
used to be measured by it.
And I doubt not but that a man may have the idea
of ten thousand miles square, without any body so big, as well as the idea
of ten thousand years, without any body so old.
It seems as easy to me to
have the idea of space empty of body, as to think of the capacity of a
bushel without corn, or the hollow of a nut-shell without a kernel in it: it
being no more necessary that there should be existing a solid body,
infinitely extended, because we have an idea of the infinity of space, than it is
necessary that the world should be eternal, because we have an idea of
infinite duration.
And why should we think our idea of infinite space requires
the real existence of matter to support it, when we find that we have as
clear an idea of an infinite duration to come, as we have of infinite duration
past?
Though I suppose nobody thinks it conceivable that anything does or
has existed in that future duration.
Nor is it possible to join our idea of
future duration with present or past existence, any more than it is possible
to make the ideas of yesterday, to-day, and to-morrow to be the same; or
bring ages past and future together, and make them contemporary. But if
these men are of the mind, that they have clearer ideas of infinite duration
than of infinite space, because it is past doubt that God has existed from
all eternity, but there is no real matter co-extended with infinite space;
yet those philosophers who are of opinion that infinite space is possessed by
God's infinite omnipresence, as well as infinite duration by his eternal
existence, must be allowed to have as clear an idea of infinite space as of
infinite duration; though neither of them, I think, has any positive idea
of infinity in either case.
For whatsoever positive ideas a man has in his
mind of any quantity, he can repeat it, and add it to the former, as easy as
he can add together the ideas of two days, or two paces, which are
positive ideas of lengths he has in his mind, and so on as long as he pleases:
whereby, if a man had a positive idea of infinite, either duration or space,
he could add two infinities together; nay, make one infinite infinitely
bigger than another- absurdities too gross to be confuted."
"The Supposed positive ideas of infinity is the cause of mistakes."
"But yet if after all this, there be men who persuade themselves that they
have clear positive comprehensive ideas of infinity, it is fit they enjoy
their privilege: and I should be very glad (with some others that I know,
who acknowledge they have none such) to be better informed by their
communication.
For I have been hitherto apt to think that the great and inextricable
difficulties which perpetually involve all discourses concerning
infinity,- whether of space, duration, or divisibility, have been the certain marks
of a defect in our ideas of infinity, and the disproportion the nature
thereof has to the comprehension of our narrow capacities.
For, whilst men talk
and dispute of infinite space or duration, as if they had as complete and
positive ideas of them as they have of the names they use for them, or as
they have of a yard, or an hour, or any other determinate quantity; it is no
wonder if the incomprehensible nature of the thing they discourse of, or
reason about, leads them into perplexities and contradictions, and their
minds be overlaid by an object too large and mighty to be surveyed and managed
by them."
"All these are modes of ideas got from sensation and reflection.
If I have
dwelt pretty long on the consideration of duration, space, and number, and
what arises from the contemplation of them,- Infinity, it is possibly no
more than the matter requires; there being few simple ideas whose modes give
more exercise to the thoughts of men than those do.
I pretend not to treat
of them in their full latitude. It suffices to my design to show how the
mind receives them, such as they are, from sensation and reflection; and how
even the idea we have of infinity, how remote soever it may seem to be from
any object of sense, or operation of our mind, has, nevertheless, as all
our other ideas, its original there.
Some mathematicians perhaps, of
advanced speculations, may have other ways to introduce into their minds ideas of
infinity.
But this hinders not but that they themselves, as well as all
other men, got the first ideas which they had of infinity from sensation and
reflection, in the method we have here set down."
This is one of the few philosophical issues in relation to which relatively recent developments in mathematics make a real difference, and threaten to enter decisively into a matter one might have thought the province of Philosophy.
ReplyDeleteLocke here seems to be taking the Aristotelian path of allowing potential but rejecting actual infinity, as well as a more specific rejection of infinite numbers.
Later Bishop Berkeley was to take aim at the use by mathematicians in the differential and integral calculus of infintary quantities or numbers (those which are infinitely small).
Since then a number of developments in Mathematics and Logic have made a significant difference.
The first was the "rigorisation" of analysis,taking place in the first half of the 19th century, which put right what Berkeley complained of by recasting analysis without the use of infinitesimals.
From there on in the news is bad for philosophical sceptics about infinity (at least in mathematics).
First Cantor came up with a coherent account of what an infinite number might be, in his theory of cardinal numbers, and these became a standard aspect of set theoretical foundations for "classical" mathematics.
These are perhaps not the kinds of infinity of which Locke and Berkeley spoke.
Later a Robinson invented "non-standard" analysis in which infinitesimal and infinite numbers are reinstated, retrospectively justifying the Leibnizian methods which Berkeley had criticised (though to make a bit of mathematics respectable retrospectively is odd, since one expects proofs to be complete in the first place).
To this one may then add the usurpation of metaphysics by physicists, who since Einstein have thought that observation and experiment can tell us about the structure of space, including whether space is or is not in fact infinite in extent.
I believed that received opinion now is that space is infinite in extent, but that the amount of matter in the universe is nevertheless finite.
How all this fits into Grice's philosophising I don't know, but I thought I would throw it in.
Roger Jones
This is EXCELLENT!
ReplyDeleteThe whole point of 'pasting' the excellent edition by Jones of Locke -- that wonderful section on "Infinity" -- was to have it on record, as it were -- since one may think that Locke's prose (however clear) may be in need of elaboration or commentary.
So I will re-read Jones's commentary from the mathematical standpoint and try to comment on a different thread.
Thanks again!