it is generally though by no means
unanimously agreed that science seeks to
uncover
laws of nature the reason it's not
unanimously agreed
is it is occasionally thought that an
emphasis on laws of nature reveals a
kind of physics bias
and surely laws do figure more
prominently in physics than in say
biology or psychology
arguably that's a matter of the
complexity of those sciences the laws
are harder to state
harder to empirically test harder to use
doesn't necessarily show that those
sciences in principle
work differently but some people think
that they do that biology explains
narratively and that biology and
psychology both appeal to goal-directed
explanations
rather than law explanations that's a
complicated question whether you can
have
sciences that don't make any interesting
or important use of laws of nature
it requires more detailed examination of
particular sciences than we're going to
be able to go into
but it's worth noting that in biology
you do have laws or at least decent
approximations of laws
like gregor mendel's laws of classical
genetics
and in the human sciences we find quite
a lot of laws mainly in something like
economics
that's a highly law governed at least
alleged science
the law of supply and demand being the
best known case
economics while we're on that subject
raises a whole bunch of issues about
what makes science science
it's highly law governed highly
quantitative
but the empirical interpretation of
economic laws is itself a vexed question
they come up with very precise models
but do they interpret their models in
terms of predictions that are tested
against the world
that's a more complicated issue than we
can quite get into but you certainly
can have laws in the human sciences
other issues crop up of course now the
notion of a law of nature
like that of explanation and that of
causation these are closely intertwined
has seemed worthy of suspicion to
empiricist philosophers
the very terms in which it's expressed
have conjured up associations with
divine decrees and other metaphysical
pictures
if there are laws of nature who laid
them down
the picture is that laws aren't just
facts about how things
are which are supposed to be observable
and testable and all that good stuff
a law seems to be modeled on this idea
that there's a necessity out there in
the world
there's this t-shirt with a picture of
einstein
um describing the speed of light 186 000
miles per second
it's not just a good idea it's the law
that's a connection between
laws in the positive sense the sort of
things lawyers study
and laws in the physical sense and the
suggestion is
that laws impose requirements on nature
and empiricists want to know what the
observable output of a requirement
on nature is so for an empiricist like
aj air this feeling that
laws um require things of empirical
phenomena is a kind of metaphysical
hangover
it's back to this idea which might be a
fine idea but is not obviously
scientific that god
laid down the laws and makes things
follow them
and that has seemed metaphysical and
hence worthy of suspicion
so laws of nature must be distinguished
from positive laws which is what you
study if you go to law school
and also from the laws of logic which
for positivists and many other people
are analytic and hence necessarily true
right it's a an analytic truth or law
that there are no square circles for
instance
but the laws of nature are synthetic
they're not true by virtue of meaning
alone
and they're contingent they could be
otherwise than they are
so even if you accept this idea that
laws impose a kind of necessity on
things or events
that the law prevents anything from
going faster than light
the decree that would back them up this
idea that god laid down the law
is itself supposed to be contingent
though it makes
certain facts necessary what do i mean
by that
well god could have set our universe up
with gravity being inversely
proportional to the cube of the distance
between two objects rather than to the
square
so the law itself is contingent even if
it makes particular events obey it given
that it's a law
so it's a contingent necessitating kind
of statement
but empiricists like air are really
bothered by this idea
that laws make things happen or prevent
things from happening
so they want to as we've seen focus on
logic and language
to explicate the notion of a law most if
not all laws are of what philosophers
call
universal conditional form we've seen
that quite a lot
the form is all a's are b's or take
anything in the universe
if it's an a then it's a b all copper
conducts electricity has been our main
example of this
that's got the right logical form to be
a law but logical form by itself is not
going to guarantee
that something is a law and some laws
like the law of supply and demand which
asserts a kind of inverse proportion
relationship don't appear to have this
form but can be
reproduced in that form all cases in
which supply goes down
k and relating price and law supply and
demand that sort of stuff
they can be assimilated to the all a's
rb's form
singular facts can be crucial to
scientific explanation or understanding
but they can't themselves be laws
the location of the center of mass of
our galaxy might be very important for
understanding a bunch of things
but it's not a law it's a particular
fact laws are
general not particular
now it is generally though not as we'll
see next time unanimously agreed
that a statement isn't a law of nature
unless it's true
seems reasonable enough but names can
mislead a bit here because there are
lots of statements that are
called laws and at least strictly
speaking are not really true
newton's gravitational law gets
corrected by einstein's general
relativity
but sort of by tradition and courtesy it
gets called a law
and it can be used in lots of contexts
as if it were true
so strictly speaking a lot of laws
aren't laws because they're not true
and a lot of things that strictly
speaking are laws get called equations
instead of laws
but an equation can have that all a's
are b's form
so that needn't be a problem
for empiricists the most common approach
to laws of nature is a regularity
account
a regularity account of laws treats them
as statements about what always happens
laws of nature report or describe
patterns in experience
rather than something above beyond or
behind
the world which explains these patterns
these are empiricist friendly theories
because they say laws of nature just
describe
what always happens but a simple version
of an empiricist or regularity theory of
laws
faces devastating problems the simplest
version would say that
any true statement that has the right
logical form
any true statement of universal
conditional form
counts as a law of nature this is a
disaster
the main problem with such an approach
is it can't distinguish laws
from accidental generalizations that's
the usual contrast that's a true
statement
of universal conditional form that just
happens to be true
rather than being a law of nature so
even if it's true
the statement all the beer in my
refrigerator is american made
does not seem to express a law of nature
it says take everything in the universe
if it's a beer in my refrigerator it's
american-made it's got the right logical
form
and it needn't be perfectly accidental i
might have a habit or a
principle that says i will always buy
american beer but it still doesn't seem
like a law of nature even if it always
turns out to be true and even though it
has
the right logical form well empiricists
then need to explain
why it's not a law of nature one
suggestion is we can disqualify the law
on the basis of its being restricted to
just one place
something isn't a law if it's just about
something as small as my refrigerator
that might be too restrictive though
remember whenever we try to restrict
bad cases we have to worry about whether
we're going to prevent good cases
and we want to allow for the possibility
that some genuine laws of nature
hold at just one place for instance on
the earth
some biological laws might be laws but
might be as it were local laws
galileo's law of free fall which turns
out not quite to be true
would be a law if it were true but it's
just about the behavior of objects near
the surface of the earth
so the fact that my refrigerator law is
about objects
near my refrigerator doesn't
automatically disqualify it
from counting as a law
vacuous laws laws that don't have
instances
present a similar kind of problem for a
regularity account
so let's take the following law all
particles that travel faster than the
speed of light are pink
now that doesn't seem true intuitively
but remember that it's equivalent to
no particle traveling traveling faster
than the speed of light is non-pink
and that does seem true so once you
realize that a statement like
all dragons like jazz is logically
equivalent to
there are no jazz hating dragons you'll
see that it's not so hard to admit
that all dragons like jazz turns out to
be true
courtesy of there being no dragons right
so our statement that all pink all
particles traveling faster than the
speed of light are pink
turns out to be true courtesy of there
being no particles traveling faster than
the speed of light
well the simple way to get around this
problem would be to require
that there be at least one instance of
something for it to count as a law
you would rule out vacuous laws you
require
that any statement to be a law of nature
must have at least one
actual instance that would get you out
of the problem of vacuous laws
but again as soon as we try to exclude
bad cases we have to worry about whether
we'll be excluding
good cases not all laws that lack
instances are illegitimate or seem to be
anyway
the fact that there are no bodies on
which there are no forces
anywhere in the universe is some
gravitational maybe electromagnetic
force
acting on any given body does not
prevent newton's first law
which describes what would how a body
that on which no forces were acting
would behave
that still seems like a law and an
important law even though it doesn't
directly apply
to any objects there are no instances of
bodies on which there are
zero forces acting
so we're going to need to buttress our
regularity account we're going to need
to impose
some more conditions to try to avoid
these problems according to which
things that don't seem like laws end up
counting and if we exclude them things
that do seem like laws get excluded
the most common way to do this involves
an epistemic regularity account and this
was aj
air's approach it distinguishes laws
from other generalizations on the basis
of how we treat them
and this approach can handle the
problems we noted above but it's going
to face
some major problems of its own so how do
we treat laws differently than we treat
accidental generalizations
well we let laws support counterfactuals
a counterfactual conditional is a
conditional that describes
what would happen if things were
different
so we can talk about what would happen
if the people in the studio here were to
pull a certain switch
the lights would go off that's a true
statement about how the world would be
if things were different and so we can
say that
if my pen were made of copper it would
conduct electricity
that's a mark that we think all copper
conducts electricity is a law
while we don't want to say if a german
beer was placed in my refrigerator it
would become an american beer
the difference between a law of nature
or a difference between
a law of nature and an accidental
generalization is
we treat laws as supporting
counterfactuals
similarly laws as we saw with hempel
hold a special place in our explanatory
practices
we can at least begin to explain why an
object conducts electricity
by saying it's made of copper if you
don't buy the covering law model we're
only beginning to explain but at least
we're beginning to explain
but arguably we don't begin to explain
why a given beer was made in america by
saying that it comes out of my
refrigerator
right true generalizations of universal
conditional form can
explain things if they're laws of nature
but if they're accidental
generalizations saying something came
out of my refrigerator does not explain
even though it's true that all beers
coming out of my refrigerator are
american
that we can appeal to that statement to
explain why the beer is american
if it were a law we could laws are
relatively central to our webs of belief
to use the quinine metaphor
they are not easily undermined by new
information or
falsified by apparent counter examples
so if i'm told that this piece of copper
was freshly mined and i've never seen a
freshly mined piece of copper before
that's not going to threaten my
confidence that it conducts electricity
and that's a mark that i think the
statement all copper conducts
electricity is a law
but if i'm told that i had some friends
over and that they brought beer and
there's a brand of beer in my
refrigerator that's never been in there
before
i'm going to have my confidence
undermined that that beer is american
new information threatens accidental
generalizations
in a way that it doesn't threaten
statements we treat as laws of nature
in addition we treat laws as more
readily confirmed or supported by their
instances
than accidental generalizations are i
don't have to sample
that many instances of copper in order
to become convinced
that all copper conducts electricity but
if you've been to say a meeting of the
american philosophical association you
might have encountered a bunch of weird
philosophers
but you're not going to be perfectly
confident that
all philosophers are weird you might
think there's a normal one out there
somewhere
and that suggests that you don't think
that all philosophers are weird
is a law all copper conducts electricity
is a law you think we could easily find
an exception even though it's generally
true that philosophers are weird
you don't think that gets support from
the particular cases in the same way
that
all copper conducts electricity does and
this actually is how nelson goodman
originally set up
his new riddle of induction or the gru
problem his idea was that the gru
hypothesis has the right form to be a
law
all emeralds are gru has the same form
as all emeralds are green
but the mark of its not being a law is
that it's not confirmed by its instances
no matter how many grue emeralds we
observe we don't
confirm the hypothesis that all emeralds
are grew
if all emeralds are green is a law it
does get confirmation from its instances
and so we increase our confidence with
each green emerald that all emeralds are
green
so on this epistemic regularity approach
to laws of nature
it's a matter of how we treat laws what
work they do
for us that distinguishes laws from
accidental generalizations
the major problem this approach faces is
it doesn't look like it can make room
for undiscovered laws
what makes something a law of nature is
how we handle it
and so something as it were becomes or
gets transformed
into a law of nature courtesy of being
treated in a certain way
in our theories and that doesn't seem to
do justice to the idea that the laws are
in some sense admittedly this is
metaphorical but in some sense the laws
are out there waiting to be discovered
by us
not made or manufactured by us we think
we're tracking something
when we um get a hold of the laws of
nature not manufacturing it
or at least many people think that
which brings us to the most
sophisticated version of the regularity
theory or this broadly
empiricist approach to laws of nature
remember on a broadly empiricist
approach
laws are going to have to be nothing
more than
patterns in experience laws are going to
have to be built up out of statements
about
the ways in which things happen
so on the systems theory the laws of
nature flow from the deep
structural patterns in actual events
we identify the patterns by figuring out
the best way of
describing the world in a deductive
system
this fits the empiricist approach
according to which we can use
observation
and logic rather than metaphysics to
solve
philosophical problems so we have no
resources other than our observable
evidence
and deductive relations we're not
appealing to
some relationship out there of
a law preventing anything from going
faster than the speed of light
all events are separate was the human
motto
so any connections between events or
statements
have got to be as it were built up by us
rather than found out there by us
connections between facts
or events are not present in observation
for people in the human tradition and
it's not kosher to claim that we can
just reason our way to these things
that would be metaphysics that would be
claiming synthetic a priori
knowledge but the systems approach is
going to come as close as it can
while retaining these empiricist
scruples to putting laws
out there so let's examine this in a
little bit of detail
what do we mean when we talk about the
best way of systematizing experience
best here means the simplest and
strongest deductive
system this notion of a deductive system
is very like the positivist conception
of theories we saw
way back in lecture seven theory is
modeled on geometry it's a set of
statements that bear
logical relations to each other it's
also even more closely modeled on the
unificationist approaches to explanation
that we saw the lecture before last
deployed for a somewhat different
purpose in the philosophy of explanation
so what do we mean when we say a
deductive system has the virtue of
simplicity
simplicity is inversely proportional to
the number
and complexity of the axioms of the
system
right so it's a nice feature of say a
geometry if we don't need very many
axioms
very many independently accepted
statements statements for which we're
not providing a reason
but we want to do this with experiential
content as we don't do it in the
mathematics of geometry
so here's a nice simple theorem
everything happens according to the will
of elvis
well we're only positing one object so
far we only have
one theorem it's a pretty special object
we've only got one argument scheme which
also is
good right so everything is to be
explained in terms of
the argument from elvis's intentions now
you might need a few more
independently acceptable sentences in
order to flesh out
the king's will you might need to look
at song lyrics pretty carefully
try to get some evidence about what
elvis will is
but there aren't going to be very many
independently acceptable sentences and
you've just got this one argument
pattern
so that's a nice simple deductive system
at the other extreme a list of
everything that happens
is a very unsimple a very complex
deductive systematization
because it imposes no order it has no
tendency to try to do the most with the
least
strength is the other main virtue a
deductive system can have
strength is a matter roughly of how
informative the theorems
are that's measured by how many
statements about the world
can be derived from the statements that
make up the theory
so a list of everything that happens is
a very strong though not a very simple
deductive system why because if you've
got a list of everything that happens
it includes everything that happens you
can derive everything that happens from
that list
the system according to which everything
happens according to the will of elvis
scores well on simplicity but badly on
strength it's hard to derive
particular predictions from it at least
not without adding a whole bunch of
other statements in which case it loses
its simplicity
so as we see the simplicity and the
strength of a deductive system
tend to work against one another it's
easy to have
a simple theory that doesn't say much
and it's easy to have a strong theory
that isn't simple the laws of nature
according to systems theorists the most
sophisticated of the regularity
theorists
consist of all of the true contingent
generalizations all the statements that
have the right logical form
and are true that figure in
all the best deductive systems that's
the rule that's a little elaborate it's
easier to see with examples
so the following statement has a good
chance of being a law of nature
according to the system's view
there are no uranium spheres that are a
mile or more in diameter
why well our best physical theories
let's assume for the sake of argument
are highly likely to belong to the best
deductive systems
why because we can do a lot with a
little to oversimplify a little bit
newton's laws of physics unify a lot of
phenomena with a few independently
acceptable statements and argument
patterns we can derive a lot of
predictions
so if our best science we'll figure in
the best deductive systematization
then we can derive directly with no
other statements
that there are no uranium spheres more
than a mile in diameter because
those theories by themselves imply that
if you put that much uranium together in
one place it would go boom
on the other hand there are no gold
spheres a mile or more in diameter
anywhere in the universe
is not a law of nature even let though
let's assume it's true
pretty plausible that it's true but who
knows it's got the right logical form
and it's perfectly true it looks a lot
like the statement about uranium
the difference is it doesn't follow from
it doesn't flow out of
the best deductive system you would have
to add it
independently as an axiom to get it into
the best deductive system
and if you add it you're lessening the
simplicity of the system
without getting a compensatory payoff in
strength
so if it's perfectly true it
nevertheless
ends up being something that just
happens to be true and the difference
between
things that need in some sense to be
true and things that just happen to be
true
is the difference between laws of nature
and
accidental generalizations that we were
trying to get at in the first place
so this is what the systems theorists
have in mind when they say that to call
something a law of nature
is to say that it is a a generalization
that is true
and figures in or flows out of two
metaphors that amount to the same thing
all of our best deductive
systematizations of the world
this looks like a promising way of
handling the problems that plagued
simpler
versions of the empiricist approach to
laws of nature
because laws that don't have instances
are allowed but they have to pay their
way in terms of the currency of
simplicity and strength so there's no
ban
on laws that don't have any instances
but all particles
traveling faster than the speed of light
are pink does not
pay its way in terms of allowing us to
derive a lot of predictions we couldn't
otherwise
have derived while newton's law saying
that
all bodies on which no forces are acting
will continue in inertial motion
arguably does pay its way and so figures
in all the best deductive
systematizations
similarly laws can be restricted in
space or time
and still count as laws if they pay off
in terms of simplicity or strength
so if we get a large payoff in terms of
unifying our experience and our theories
by talking about laws that hold only on
earth if they let us derive a lot of
predictions using a
modest number of hypotheses then they
count as laws
but it's highly unlikely that they're
going to be laws governing the behavior
of objects in my refrigerator
we would need to posit them
independently and we derive
relatively few observational predictions
from those independent posits
so even though it might be true that all
the beers in my refrigerator are
american
it won't be a law because it would have
to be added to any
deductive system and it detracts from
the product of simplicity and strength
in the system
arguably this systems approach explains
why the laws of nature
have the role they have in explanation
why they support counterfactuals
so for instance if unification provides
the right account of explanation
then the depth of a statement in our
best theories
pro is a measure of how unifying its
force is
um and similarly the right way to
evaluate counter factuals
for an empiricist is going to be given
by how much havoc it would wreak with
our theory
if we evaluated the counter factual
differently so how do we decide
what would happen had oswald not shot
kennedy
well the way to evaluate counterfactuals
is first we try to keep
the laws of nature constant why because
if we change them
huge changes ramify throughout our
theory so we minimize
large widespread violations in laws of
nature
next we try to make the situation as
spatio-temporally continuous with our
world as possible
so we could say has had oswald shot
kennedy there would have been
uh black hole emerging in dallas oswald
not shot kennedy excuse me
a black hole would have emerged on the
grassy knoll and
uh all of matter would have gotten
sucked into some other dimension or
something like that
experience doesn't directly tell us what
would have happened had things gone
differently
but there are more and less reasonable
answers to these things
and the measure of reasonableness is a
matter of how
deeply ingrained in our best theories of
the world a given statement is
so even though that was an important
particular fact we don't need to change
much about how the universe would have
gone in order to talk about how things
would have been differently
in those cases what we preserve are laws
not facts even when they're important
facts because changing facts
changes to resort to the quinine
metaphor things at the periphery of the
web of belief
not things at the center of the web of
belief
so when we evaluate counterfactual
conditionals we're asking which
possible worlds are close to our
possible worlds
all right to our actual world sorry and
we do that by asking
whether according to our best theories
the world works
fundamentally differently from our world
and so this uh systems approach solves
the problem with the epistemic
regularity view the big problem with the
epistemic regularity view
because what makes something a law is
not that you and i believe it we don't
turn things into laws
by believing them or using them in a
particular way the idea is
our best theories structured in the best
possible way
determine which things the laws are it
doesn't matter whether you or i believe
that things are that way
what matters is the deductive
relationships that hold among them so
it's got a kind of objectivity what's
nifty about the system's view
is it makes laws depend on the
best patterns in experience but best
here doesn't mean
best as judged by you or i it means best
according to
a standard of maximizing simplicity and
strength
so it's as objective an account of the
laws of nature
as an empiricist view is going to be
able to get
because all the empiricist has to go on
is patterns in experience
and deductive relations that hold among
them
so though we're far from having a best
deductive systematization of our view
of our theories and it's not clear what
it would look like if we did
this approach can build laws and hence
explanation
out of mere deductive relations on this
approach
to say that the laws of nature forbid
something from happening
is not to say there's some metaphysical
relation of forbidding out there
it's to say the best version of our best
theories forbids this thing from
happening
and so this builds in as much mind
independence
for the laws of nature as you're going
to get if you're going to insist
that laws have to be built out of mere
patterns and experience and deductive
relations
so remember hume had made causation in
here in our heads
rather than out there there's no
necessity of the cue ball moving the
eight ball the necessity is in
our thinking about cue balls and eight
balls
similarly the systems approach treats
laws and causes
as in here in the sense of in our
theories rather than out in the world
but it's in here in the sense of an
idealized version of our theories
and so it's independently of what you
and i think and our current best
theories
and so the regularity or systems
approach uses all of the resources
available to empiricists
to prevent laws from having to be about
some kind of cement of the universe
some kind of stop sign that the world
gives to particles that try
traveling faster than the speed of light
and yet
it makes laws found rather than made
we'll look at a competing approach to
laws of nature in our next lecture
in this lecture we take a very different
look at what laws of nature might
believably be
in our last approach to laws of nature
and throughout the course we've been
more or less
assuming a starting point of a kind of
hume inspired empiricism
according to which observation just
presents occurrences
and laws of nature on such a view can
only be patterns or regularities in
experience
we saw the best shot that this kind of
classic empiricist approach
can take to laws of nature last time for
empiricists laws don't
say anything different than accidental
generalizations do
they are both true statements of
universal conditional
form a law and an accidental
generalization
each say of all a's that they are b's
what makes some statements of true
conditional form
laws rather than accidental
generalizations is that they get used in
a certain way
or fit into a certain system it is what
is done
with a true statement of a certain
logical form that
constitutes its as it were lawfulness
in addition to its truth and logical
form
but laws themselves have as a matter of
their content
just relations that are asserted among
objects
all objects that are made of copper are
objects that conduct electricity
that's a pattern that we can observe and
experience
and if we could solve that nasty problem
of induction we're entitled to project
that pattern into the future and so the
empiricist credentials of such a view
look pretty strong
we're taking observation and we are
generalizing it and then we do something
with
certain observation statements that
allow us to treat them as laws
or our theories on the systems approach
do something
with certain statements about observable
reality that allow them to serve as laws
and this generalizes somewhat to
statements about unobservable objects
like electrons
via the uh received view of theories and
the empiricist approach
to how meaning goes from observation up
to the theoretical parts of our theories
necessitarians about laws on the other
hand
take them to describe not the behavior
directly of observable objects
but tendencies or powers not themselves
observable
that explain observable phenomena
on this view laws have a different
logical form than they do for
empiricists
a law does not assert a relationship
between objects
it does not say of all copper things
that they are
electricity conducting things instead it
asserts a relationship between
properties it says something like being
made of copper
makes for or makes you conduct
electricity
it's a relationship between copperness
and
electricity conductivity
if that sounds weird it's because
against an empiricist background it is
weird
you don't see the property of copperness
at least in the usual sense of
seeing and if we follow hume at all we
certainly don't see
copperness making things conduct
electricity
hume had insisted that experience only
gives us one damn thing
after another and that as presented in
experience
each event is distinct from any other
event this view insists that some
properties make other properties hold
some things
make other things happen so these
necessitarians
understand they're going well beyond
what the empiricist scruples of somebody
like hume and the empiricist scruples of
ordinary philosophy of science
permit they are going behind or beyond
observation
but they think they have solid reasons
for this they think that if there are
laws of nature
they will not be the sorts of things
that can respect these empiricist
scruples
so necessitarians admit that experience
only shows
this piece of copper conducts
electricity that one conducts
electricity
at best experience in a reasonably
direct way
with induction and some other friends
can show us that all
copper conducts electricity
necessitarians freely admit
that experience does not in a
full-fledged sense show us that copper
must conduct electricity nevertheless
they say
if it's a law that copper conducts
electricity we've got a very different
kind of statement than just
that all copper does conduct electricity
if all we have are generalizations about
objects if all we have are statements of
the form
take everything in the universe if it's
an a then it's a b then
there are no laws of nature so they
insist
on going beyond observation because they
think it's at least plausible
that there are laws of nature and that
laws of nature
go beyond observation in a way that the
traditional empiricist view has trouble
with
according to this theory laws do not
describe or report
patterns in experience or they at least
don't merely do that
laws govern experience laws don't just
say what always happens they say what
has got to happen
no matter how universal or how true a
generalization is
all copper conducts electricity all the
beer in my fridge is american
it doesn't say the same kind of thing
that a law
says now we're here at the level of
semantics we're not talking about what
we
do with a statement we're talking about
what the statement says
and for necessitarians a law says not
just
that you won't find any non-conductive
copper but that you can't
find any non-conductive copper because
being made of copper means you must
conduct electricity so there's a kind of
physical necessity remember we've seen a
couple times in this course
necessity comes in various flavors
there's logical necessity or possibility
it's supposed to be impossible in a very
strong sense that there be a round
square
how many corners would a round square
have
and there's different kinds of lesser
kinds of possibility and necessity if i
played a one-on-one game of basketball
with shaquille o'neal it's no accident
that he'd beat me
he's sort of gotta win in a certain
sense but here we're talking about
an in-between kind of necessity a
physical necessity such that being made
of copper
is not a matter as a matter of meaning
entailing
conductivity but it physically makes
something conduct electricity
and empiricists are mystified by this
notion of necessity
they think all necessity is linguistic
necessity
my dissertation advisor when he was
chair of the department said the
strongest kind of necessity is
administrative necessity
it's much tougher than logical necessity
it's much easier to make a round square
than it is to convince a dean to do
something that the dean says is
administratively impossible
so empiricists want to know what we
could mean by this idea of something
physically rather than logically
requiring something else
the idea of necessity or requirement is
for them a conceptual
notion necessity happens within our
theories or concepts or language
not out there in the world
necessitarians on the other hand assert
that
laws anyway if there are any require
relationships of physical making this is
the very notion that aj air had mocked
as a kind of metaphysical hangover
air said the only reason we're tempted
to talk this way is this sort of
lingering idea that the deity or some
force behind nature
laid down the laws and said no no no you
particle don't get to travel
faster than the speed of light i mean
that he thinks is an unfortunate
remainder of intellectual history not a
sort of scientific insight
so nothing scientifically respectable
could
forbid things from happening or require
things to happen
science just talks about what does
happen
so necessitarians are talking a
different kind of language
from our classical empiricists a
necessitarian says
given a contingent fact it could be
otherwise right
god could have made copper so that it
didn't conduct electricity
but given the contingent fact that being
made of copper
makes for conducting electricity it is
necessary that a given bit of copper
does conduct electricity
so there's a contingent truth that makes
other truths
physically necessary and it's this
notion of physical necessity
that empiricists like air claim not to
be able to understand
so the challenge for necessitarians is
to try to make sense of this notion
um in somewhat scientifically if not
directly experientially terms
uh experiential terms sorry um so one of
the metaphors that fred dretzky one of
the leading necessitarians appeals to is
legal
and remember this was the very kind of
metaphor that air had mocked
that to talk about a law of nature
sounds like a kind of decree
and science doesn't study decrees that
somehow linger behind the natural world
so in dretzki's model the constitution
needn't have said
needn't have required that the president
consult congress but
before declaring war the uh constitution
is contingent on this
it could have said something different
than it does say
but given what it does say it's no
longer discretionary for the president
the president
must consult congress before declaring
war the constitution requires it
makes it happen that's the model here
something in nature makes something else
in nature happen
like the systems approach the
necessitarian approach has certain
virtues because it makes laws of nature
robust
in a way that the simple regularity
accounts according to which a law of
nature is just a pattern in experience
couldn't distinguish laws from
accidental generalizations
so the necessitarian account can handle
the problems that plagued the simple
versions of regularity accounts
so for instance vacuous laws laws that
don't have any instances
looked like they counted as genuine laws
of nature on a simple regularity account
because they were true statements
of the right form
so there was trivial that all particles
traveling faster than the speed of light
are pink
turns out to be true on a simple
regularity account
for an essetarian that's no law of
nature at all because of how demanding
the notion of a law of nature is
for a necessitarian a law says that the
property of traveling faster than the
speed of light
necessitates the property of being pink
and that clearly is false now
empiricists are going to want to know
how we know that that's clearly false
we'll come back to that kind of worry
but it's not a law we have no problem
excluding it
from being a law if we're necessitarians
because
it doesn't fit our conception of what a
law is there's no relationship of
making between the property of going
faster than the speed of light
and the property of being pink so
because this is a demanding conception
of laws we're generally not going to
have
problems excluding flimsy looking
apparent laws that's a problem that
plagues simple regularity views
not demanding necessitarian views their
problems are going to come from the
other side as it were
like the deductive systems approach the
most sophisticated version of the
regularity view with which we ended last
time
this view will permit laws that don't
have instances
if they pass the stringent test
there probably are no objects in the
universe that actually slide down
frictionless planes
but if there were any they
would meet a certain sort of law because
the property of being an object sliding
down a frictionless plane
does necessitate certain claims about
how an object moves
so even if the property is never fully
instantiated
there can be a law because there's the
right sort of relationship between the
property of being
on a frictionless plane at a certain
angle of course with a certain motion
and obeying certain laws similarly if
the universe were newtonian
which it isn't being inertial
necessitates having
zero acceleration there's a the right
sort of relationship
between the properties and so
laws that don't have instances can still
be laws on this view because
laws are not directly about objects at
all
they're about properties that objects
have
so on this view there's relatively
little problem distinguishing
laws from accidental generalizations
being made of uranium necessitates
requires being less than a mile in
diameter
because you'll blow up if you try as it
were to be uranium and more than a mile
in diameter
but being made of gold does not require
being less than a mile in diameter it
might be the case that nothing is both
gold and less than a mile in diameter
but it's not
required to be the case and so the
former is a law and the latter isn't
now it's clear on this kind of a view
that laws are discovered
not made the systems view has a very
interesting position on this issue right
laws are not made courtesy of any actual
theorizing we do
but laws do fall out of our best
possible theory so they're kind of on
the border between being made by
us and discovered by us the
necessitarian view takes a clear stand
on this
the law is out there it's a metaphysical
kind of critter
and we discover it these views are
metaphysically and
epistemologically ambitious they refuse
to constrain themselves within the
limits of what experience
more or less directly shows
and they think they're entitled to do
this because of the payoff for good
theorizing
of discarding these constraints so these
relationships of necessity of one
property making another property obtain
explain for instance why laws support
counterfactuals
on the regularity view a law is
something like all copper conducts
electricity
and it's not clear how we get from all
copper does conduct
electricity which is a statement in the
indicative
mood it's a statement about what happens
to a statement
if this pen were made of copper it would
conduct electricity
so empiricists say that a law does
support a counterfactual but they don't
have much of a story about
how the law supports a counterfactual we
talked about this a little bit last time
their best explanation here is
counterfactuals are to be evaluated in
terms of a kind of nestedness
or importance in our web of belief but
the necessitarians want to point out
that the law is a statement about what
always happens in the world
right all copper does conduct
electricity the counterfactual is a
statement about what would happen
in a different possible world and
there's an inferential
move there that's a little tricky for
regularity theorists empiricists to
explain
the necessitarians think they have a
much easier time here
it's easy to see how we can get from
being made of copper
requires necessitates makes something
conduct
electricity that does seem to imply
if this pen were made of copper it would
conduct electricity
because we got the premise that
copperness makes
for requires conductivity relations
between properties
carry across possible worlds any world
in which something is copper
is a world in which it conducts
electricity if copperness
carries with it conductivity
and this same necessity explains
explanation
necessitarians think that empiricists or
regularity theorists
have a hard time explaining why
explanation works
let me see if i can make that clear the
fact that all copper does
conduct electricity implies that a given
piece of copper
will conduct electricity but to imply
is not yet to explain
even to be implied by the best system of
generalizations
is not yet to explain according to
a necessitarian the best system of
generalizations just says
according to our best theories this sort
of thing always happens
that's all the explanatory oomph that's
all the explanatory
juice that an empiricist can have and an
essentarian says that's not
enough we need more for laws we need
more for explanation
being deduced from something even being
deduced from a lovely generalization
doesn't show why something is true it
doesn't explain being deduced from
something won't explain you
unless you're being deduced from
something that already has explanatory
force so for instance if i said
every marble in the universe is red that
doesn't imply
that i can't find a non-red marble it
implies that i won't
but laws of nature say make claims about
what must happen it doesn't just say i
won't find
some non-conductive copper it says i
can't
and that's a very different kind of
claim one that goes farther beyond
experience
than the empiricists are quite willing
to bite the bullet and admit
according to necessitarians so for a
necessitarian laws explained precisely
because they are not
generalizations about what always
happens
there are much stronger claims about
what must happen and the necessitarians
think we should get over that
and discard the empiricist scruples so
this controversy between the systems
approach and the necessity approach
raises deep issues about what is
fundamentally explanatory
is it enough to say of something that
it's the kind of thing that always
happens
or to really explain do we have to in
some sense say this sort of thing
must happen and there are costs and
benefits to each approach
empiricists and necessitarians have
strong disagreements about
the epistemology and the metaphysics of
a notion like
necessity of making happen empiricists
will raise the epistemological issue how
can we ever
see when something makes something else
happen
you're bringing in some kind of platonic
forms some notion of
the a thing called copperness that must
have some weird kind of existence in
some platonic heaven or something like
that
we shouldn't be taking a notion like
that scientifically seriously
we should require that science constrain
itself by what it sees
they want to know how we can tell when
we know when we see something make
something else happen or necessitate
something
any relationship of making has got to be
grounded in some fact
about what actually happens according to
empiricists
counterfactuals have to hold in virtue
of something
copperness making for conductivity has
to hold in virtue of some more
basic fact and the way they would press
this point is saying
we know at least sort of what grounds
the must
in the president must consult congress
before declaring war
it's some kind of sanction the supreme
court will slap the president on the
wrist or the president won't get
reelected or something
there's got to be some basis according
to which the must
holds and notice that's back to that
metaphysical hangover idea
that must's can only be some notion of
decrees
a lawgiver or a sanction
so empiricists think that laws cannot
float free
about particular facts about what
happens
necessitarians think that to say that
something is a law
is to say it imposes requirements on
what can happen
and that goes well beyond what does
happen empiricists don't want us
in science to be going that far beyond
what does happen
the empiricist will maintain that we
have to build our laws and our
conception of what's physically possible
what would be the case if the laws of
gravitation were different
all of that's got to be grounded pretty
tightly in what's physically
actual one way of making this point is
to say any two worlds that have the same
facts have got to have the same laws
the idea is if the laws can outrun the
facts
we'd have no way of factually testing
laws
we'd be slipping into metaphysics in the
pejorative sense
the laws would outrun any factual
constraint on them
so there's no change at the level of
laws without some change at the level of
more basic
facts the necessitarian is going to
reject this requirement though
the necessitarian's going to say isn't
it possible
that the facts about what actually
happens
are insufficient to determine the laws
about what can
and can't happen so imagine there are
two particles that are extremely rare
and have never been studied they have
never interacted and they never will
interact there is no actual fact about
what will happen
when they interact but isn't there room
for the idea that the laws of nature
tell
what would happen if they ever were to
interact
they think the ambitions of science push
it
beyond the kinds of constraints of the
possible
by the actual that empiricists require
so there's deeply competing intuitions
about whether
science is constrained by all of the
actual facts
or whether sciences need to explain
to impose order and laws on things
requires it to stretch evidence about
what actually happens
into claims about what could and
couldn't happen
or what would happen if things that
never will happen
were to happen the necessitarians make a
conditional claim
if there are laws there are true
statements about
relationships between say copperness and
conductivity
these things go way beyond observation
but if we can't make legitimate claims
like that then
there are no laws of nature and so they
rest
on the intuition that science can
discover laws of nature
and so they find empiricism timid in its
unwillingness
to go beyond observation and say we can
think our way
on the basis of observational evidence
to facts about
what would happen in different
circumstances than the actual ones
which raises the question of whether in
fact there are laws of nature
and an important related argument
offered by the philosopher of physics
nancy cartwright emerges here
she suggests either that the laws of
nature are
false but can be used to explain things
or that they're true but are useless for
explaining things
it's an unpalatable dilemma what does
she mean
our most fundamental laws she says don't
describe the actual behavior of bodies
the law of gravitational attraction put
forward by newton
only says how bodies would move if only
gravitational forces were acting on them
but that's almost never if at all true
there are generally say electrical
forces acting on bodies
so almost never will we be able to say
of an actual body that it will obey
this law for the law to be true
it would either have to be tremendously
restricted it would have to apply to
only those bodies on which
only gravitational forces are acting and
there might not be
any such bodies or the law would have to
be what philosophers call
hedged protected by a keterous paribus
clause and all other things equal
clause so we can make the gravitational
law
come out true but the strategy we use
to make the law come out true threatens
to rob it of any application
and of any explanatory power we need the
law
to apply to bodies if it's going to
explain what happens with their motion
and since all other things are hardly
ever equal a law that just says
here's how bodies move when according to
the gravitational force all other things
equal
doesn't tell us much about the actual
behavior of bodies since all other
things are hardly ever
equal cartwright thinks her approach is
friendly to a necessitarian construal of
laws
on her view laws of nature or laws of
physics
don't describe what actually happens
they describe
tendencies or powers that underlie
or explain what happens the
gravitational law
does not talk about the actual motion of
bodies
it talks about gravity's tendency to
produce
motion in bodies and that is not itself
a directly observable thing because
they're usually
interfering forces so if the law were
true
about observable objects it could
explain them what it's true of
is not about the observable behavior of
objects but
tendencies of objects to behave in
certain ways and the tendency is not the
behavior
we saw this way back when when we
realized that fragility
a tendency or disposition property
doesn't reduce to
actual instances it's something behind
the instances that explains
the instances it outruns experience
now cartwright's opponents have a few
options available to them they can try
to say that the laws describe
actual things rather than powers or
potentialities or tendencies
the actual thing would be a component
force
now what's the difference between saying
that a gravitational law describes a
real component force versus saying it
describes a
tendency for bodies to behave in a
certain way
cartwright's argument which is
enormously controversial says that you
can't treat component forces
as fully real because if they were fully
real
they would be forces in addition to net
forces you'd be double counting your
forces
net forces explain how objects actually
move but net forces are products of
multiple tendencies of objects the way
an object actually moves is a product of
a bunch of forces acting on it
but you don't want to treat each of
those forces as a
different thing on top of the net force
but many of cartwright's opponents think
you can
find a way it gets metaphysically a
little tricky for our purposes
to count a component force as a thing
that's not an additional force that has
to be added on top of
the net force i think there's a more
interesting approach here which is we
can use context
to preserve the truth of the unhedged
law
that here's how an object behaves if
only the gravitational force is acting
on it
so if i'm moving out of my house i can
say my house is empty
and if you and the real estate agent
come in and say no your house isn't
empty look there are light bulbs in the
fixtures
well there's something in my house and
in a certain sense if there's something
in my house it's not empty
but what counts as a thing in the
relevant sense is specified by context
to say that your house is empty in the
real estate context
is to say it's got no furniture in it
it's not to say it's got no air
molecules in it
or light bulbs similarly you don't
falsify a law
like metal bars expand when heated when
you point out that if somebody is
hammering on both ends of the metal bar
while it's being heated it won't expand
the the law still holds what counts as
holding is specified by context
you don't falsify a law by saying that
other things can override or impede it
so in that view
gravitational forces have the effects
they have
maybe they describe tendencies maybe
they describe actual behavior
but what the gravitational law says is
specified by a context in which
the theoretical statement is connected
to observation in the same way that
whether i've said something true or
false when i say my house is empty
depends on whether i'm doing a bizarre
physics experiment
in which case it's got to be a vacuum
right or whether i'm just showing my
house to a prospective buyer in which
case light bulbs don't count as
falsifying
the emptiness of the house what really
matters here is this is our deepest
take so far anyway at the tension
between
sciences urge to constrain itself
to the observational evidence to not
make claims that themselves cannot be
cashed out in experiential terms
that's what stands behind the empiricist
view you never
see anything having to happen you only
see it happening
and so they say if there are laws they'd
better
obey these empiricist constraints a law
has got to be some kind of pattern in
experience or something we can
deductively build up
out of a pattern and experience but
there's a an equally genuine competing
strand in science which says
science explains it explores the
structure of the world it talks about
how things would would be if the
universe were different science is
ambitious and the ambitions of science
suggest that something like a law of
nature doesn't just talk about what does
happen
it talks about what must and what cannot
happen
and if that's the legitimate role of
scientific claims then we might have to
jettison the idea that science is
strongly constrained
by observation of what does and doesn't
happen
this tension we've seen it recur in
talks about meaning and about evidence
and we're going to see it
throughout the remainder of the course
because these are both internal
legitimate aspirations of science
deeply difficult to reconcile with one
another and we'll turn
to an a new kind of metaphysical problem
here
in our next lecture about whether and in
what sense things like biology might
reduce
to physics