Think: A Compelling Introduction to Philosophy (32 page)

Induction is the process of taking things within our experience to
be representative of the world outside our experience. It is a
process of projection or extrapolation. But it is only part of a wider
process of trying to increase our understanding of things. In the
final section of this chapter, I want to introduce some of the reasonings that this involves.

Suppose we have a complex system. We have various features,
which seem to interact. We can find the ways in which they seem to
interact, by noticing changes and variations. We might be able to
plot these against each other, and find reliable relationships.
Boyle's law, that the pressure of a given mass of gas is inversely proportional to its volume, at a given temperature, is an example. This
is a purely empirical law. It is found to hold within experience, and
we take it to hold across the wider world. Some disciplines would
be mightily pleased if they could get that far. Economics, for instance, wants to find the right features of an economic system, and to be able to plot the relationships between them reliably. And this
proves very hard. It takes art and craft, and most attempts crash in
flames. We are apt to forget that the same was true of physical science. For example, it took a century of effort for scientists to learn
to identify the energy of a mechanical system as its salient feature,
whose conservation enabled them to predict its behaviour. This is
a historical fact that science teachers should be made to write out a
hundred times, when they upbraid children as `dumb' because they
do not cotton onto the idea immediately.

If an economist has a story about the right variables and the relationships between them, it can be called a model of the economy.
But even if we had such a thing, we might still feel we did not understand what was going on. Isaac Newton (1642-1727) had a law
plotting the gravitational attraction between bodies as a function
of their masses and the distance between them: the famous inverse
square law. But both he and his contemporaries felt that this gave
them no real understanding of why gravity operated as it does. As
with Boyle's law, we can say that while it is all we have got, we know
something about the system. But we do not really understand why
it is behaving as it does. Why should pressure vary inversely with
volume? If it always does, why does it always do so? And why
should constancy of temperature be important?

These questions were answered by providing a model in a more
robust sense. The kinetic theory of gases sees gases as volumes of
molecules in motion. Pressure is the result of the impact of these
molecules on the walls of the container. The molecules speed up
with increased temperature. Once a gas is seen like this, we have a
mechanism, and given suitable assumptions, the empirical laws such as Boyle's law can be derived from the nature of the mechanism.

Finding a mechanism does not bypass the problem of induction. The continued uniform behaviour of items in a mechanism is
a projection or extrapolation from what we have found so far, just
as much as anything else. But it reduces the number of independent assumptions we need to make. A few stable features of things,
and reliable interactions between them, might explain others. If we
take the stable features for granted, we can explain the others in
terms of them. These represent the explanatory and simplifying
ideals of science.

But what kinds of thing count as satisfactory `mechanisms'?
Things whose behaviour we understand `clearly and distinctly'? Or
something else? The answer to this question opens one of the most
exciting chapters of modern thought. Nearly everyone is inclined
to think that there are some kinds of systems that we understand
better than we understand others. To most people, some kinds of
causation, like shunting, seem especially intelligible, whereas others, like action at a distance, or the effects of body on mind, seem
very mysterious. In fact until Hume, almost everyone-both
philosophers and natural scientists like Newton-thought this.
They thought we had a priori knowledge of what does cause what,
and still more, of what could not cause what. We have already seen
this. Even Newton thought that it was clear that gravitational attraction could not be a case of action at a distance. He thought that
any idiot could see that if the Sun exerts an attraction on the Earth
this must be because of a chain of some kind between them. Causation had to be a matter of pushes and pulls:

That gravity should be innate, inherent and essential to matter, so that one body may act upon another at a distance
through a vacuum, without the mediation of anything else,
by and through which their action and f force may be conveyed
from on, to another, is to me so great an absurdity that I believe no man who has in philosophical natters a competent
faculty of thinking, can ever fall into it.

Surely it `stands to reason' or is `clear and distinct' or `a priori' that
a body cannot act somewhere where it is not! We still reason like
this when, for instance, we attempt to show by pure reason that the
Universe must he the creation of a god. We are supposing that we
know what kind of thing must cause some effect, and what could
not cause it.

Hume blows this rationalism right out of the water:

I shall venture to of fire, as a general proposition, which ad-
nnits of nto exception, that the knowledge of this relation is not,
in arty instance, attained by reasonings a priori; but arises en-
tirelyfront experience, when we find, that any particular objects are constantly conjoined with each other. Let art object be
presented to a man of ever so strong natural reason and abilities; if that object lie entirely new to him, he will not be able,
by the most accurate examination of its sensible qualities, to
discover any of its causes or effects. Main, though his rational
faculties be supposed, at the very first, entirely perfect, could
not have inferred from the fluidity, and transparency of water,
that it would suffitcate hint, or front the light and warmth of
fire, that it would consume him.

As a good psychologist should, he gives an explanation of the
prejudice that we can argue a priori about cause and effect:

We fancy, that were we brought, on a sudden into this world,
we could at first have inferred, that one Billiard-ball would
communicate motion to another upon impulse; and that we
needed not to have waited for the event, in order to pronounce
with certainty concerning it. Such is the influence of custom,
that, where it is strongest, it not only covers our natural ignorance, but even conceals itself and seems not to take place,
merely because it is found in the highest degree.

Hume knew that philosophers and scientists hankered after an
ideal of `insight' into the laws of nature: something like a geometry
or algebra enabling them to see why events fall out in patterns that
are necessary, mathematically certain. They wanted a Cartesian
`clear and distinct' perception of why things have to be the way they
are. But Hume believes that this goal is an illusion. Nothing the scientist does would accomplish it.

It is good to remember here that when Newton published Principia Mathetnatica in 1687, revealing the laws of motion, there were
scientists of his time who were disappointed. They wanted an insight into what gravitational attraction is, but Newton only told
them what it does. Newton tells you how bodies accelerate towards
each other, and that is all. Hume argues that the kind of thing Newton did was the only kind of thingscience can ever do. He holds that
anything else represents an incoherent ideal. In the following quotation `philosophers' are scientists, and `philosophy of the natural
kind' means what would now be called natural science, and especially physics and chemistry:

Hence we may discover the reason why no philosopher, who
is rational and modest, has ever pretended to assign the ultimate cause of any natural operation, or to show distinctly
the action of that power, which produces any single eftect I'll
the universe. It is confessed, that the utmost effort of human
reason is to reduce the principles, productive of natural phenomena, to a greater simplicity, and to resolve the many particular effects into a Jew general causes, by means of
reasonings Jronn analogy, experience, and observation. But as
to the causes of these general causes, we should in vain attempt their discovery; nor shall we ever be able to satisfy ourselves, by any particular explication of them. These ultimate
springs and principles are totally shut up from human curiosity and enquiry. Elasticity, gravity, cohesion of parts, c onnmu-
nication of motion by impulse; these are probably the
ultimate causes and principles which we shall ever discover in
nature; and we may esteem ourselves sufficiently happy, if, by
accurate enquiry and reasoning, we can trace up the particular phenomena to, or near to, these general principles. The
most perfect philosophy ol'the natural kind only staves off our
ignorance it little longer.

What we have here is a splendid rejection of the rationalist ideal. In
its place we seem to he left only with more or less luniliar systems.
At any time those with which we are comfortable provide 'paradigms, or systems against which we compare others.'I'hey give us
our sense of what would count as a satisfactory explanation. But
without the rationalist ideal, we become aware that this sense is
perhaps itself changeable. If we replace `reason' by 'habit and custom', then cannot our customs and habits change? The famous
philosopher of science Thomas Kuhn (1922-96) argued that indeed they can. 'Normal' science proceeds in the light of a set of
paradigms, or implied views about what kind of explanations we should hope for. Periods of revolutionary science occur when the
paradigms are themselves challenged. Science is to be seen as `a
series of peaceful interludes punctuated by intellectually violent
revolutions'. After the revolutions, our sense of what makes for a
comfortable explanation of why things hang together changes.

Some people get quite excited quite quickly by this kind of
thought. They take it to suggest a kind of`relativism', whereby some
people have their `paradigms' and other people have others, and
there is no judging which is better. But that is unwarranted. There
may be better or worse paradigms. Looking at the sky as an opaque
veil with holes in it through which we see specks of the heavens beyond was once a paradigm or model of the way the heavens are. We
believe that we know better, and I hold that belief too. Paradigms
can be asked to show their worth, and some of them do not
stand up.

Thus, suppose it is true that we inevitably approach the world
with a particular set of preferred categories, partly set by our culture and history. It still does not follow that all such sets are equally
`good'. Some sets have been discarded for good and sufficient reason. A scientific environment is (ideally) an environment in which
the constant process of experimenting, predicting, and testing,
weeds out the bad ideas. Only the ones that survive go on into the
next generation. This is not to say that actual scientific environments are as ideal as all that: at any time science can no doubt boast
its fair share of blinkers, prejudices, and distortions. But the
process contains within itself the mechanisms of correction. We
might remember here the discussion in Chapter i, when we criticized Descartes for not taking account of the `self-corrective' nature of the senses, whereby illusions are detected as such. Science
similarly contains within itself the devices for correcting the illusions of science. That is its crowning glory. When we come upon
intellectual endeavours that contain no such devices-one might
cite psychoanalysis, grand political theories,`new age'science, creationist science-we need not be interested.

In this chapter we have discovered some of the elements to notice in our reasonings. We have seen some of the ideas that underlie formal logic. We have distinguished processes of inductive
reasoning, and seen how dependent we are on brute faith in the
uniformity of nature. We have a sense of how to reason about the
probability of things. And we have looked a little at processes of
model building and explanation, and been led to mistrust a priori
reasonings about cause and effect. All these give us tools to be used
as we go on to think about the world and our place in it.

IN THE SIX CHAPTERS so far, we have visited six problem areas.
These were: thoughts about our own global reliability, thoughts
about mind and body, thoughts about freedom and fate, thoughts
about the self, thoughts about God, and thoughts about the order
of nature. These are each notorious areas of difficulty, where the
structure of our thoughts, or the way to think properly, are hard to
discern. We might hope, by comparison, that thinking about the
world around us is relatively problem-free. In this chapter, we visit
areas in which a little thought generates trouble about that, as well.