Deriving OUGHT from IS [ was Re: [evol-psych] Re: The Moral Animal ]
- On Sat, 1 Feb 2003 01:49, Jeremy Bowman wrote:
> A lot of people seem to think that Hume's distinction between "is"There is a subtle flaw in your argument. Suppose I am a scientist who
> and "ought" applies only to MORAL "ought"s. But no "ought" of ANY
> kind can be derived from factual statements alone.
> (To "derive X from Ys" here means: "X occurs as the conclusion of a
> deductively valid argument whose premises are exclusively Ys".)
> There is nothing terribly mysterious about it. It is simply that a
> genuine "ought" expresses a desideratum of some kind, which may or
> may not be realised, whereas an "is" describes an actual state of
> Take a mundane example: "This car's tyres ought to be kept at a
> pressure of 30 pounds per square inch". It's pretty obvious that even
> if we decide to treat this as a "fact" -- so that the quoted sentence
> is literally true -- it is a very different sort of "fact" from, say,
> the brute fact of the tyres' ACTUAL pressure.
> No one denies that there are clear REASONS why the tyres ought to be
> kept at that pressure. There are obvious drawbacks to driving with
> the tyres at too low or too high a pressure. The manufacturers arrive
> at their specifications following rigorous testing, which is enough
> to very narrowly constrain the range of "best pressures for normal
> conditions" -- so there is no scope for disagreement about it.
wishes to derive the pressure that a car's tires OUGHT to be kept at: I
weigh the car, fully laden with passengers and luggage, I measure the
air temperature and the properties of the surface on which the car will
be driven, etc.
But there is one factor which I haven't accounted for: the purpose of
the car (or the REASON, as you put it). Being entirely ignorant of the
uses of cars (perhaps I am a Martian) I do what any respectable
scientist does: I capture a driver and analyse his brain to discover
the answer (Martian science is terrifically advanced). Or perhaps just
ask him "What do you want to use the car for?"
This PURPOSE is entirely determinable, so far as the driver is able to
articulate it. Even if the driver is unaware of his *real* motives for
driving (perhaps he says he wishes to get from point A to point B as
quickly as possible, as cheaply as possible, and as safely as possible,
when his actual, hidden purposes are to blow out a tire at 120mph, spin
out of control and be killed in a flaming wreck) then I should be able
to use statistical analysis of the behaviour of drivers just like him
to determine the underlying, hidden motives.
So you can see, PURPOSE or REASON themselves become just another
variable to be measured. Admittedly there are many potential pitfalls
and difficulties in doing so, but as a matter of principle that is
I don't see the advantage of the equation IS + PURPOSE -> OUGHT. As I
see it, PURPOSE is merely another IS. It is true that if you change the
PURPOSE the OUGHT also changes; but if you change any of the ISes
(change the material of the tyre) the OUGHT also changes.
Some people might argue that PURPOSE is not something that science can
measure or describe -- after all, we can't derive it from quantum
mechanics. But so what? Science is full of quantities that can't be
derived from quantum mechanics, including the electron structure of the
hydrogen atom. The coefficient of friction between the tire and the
road is one such variable: even though it is derived from the molecular
structures of the road and tire, their geometric shapes, and the
electromagnetic forces between them, in practice we treat it is an
independent variable to be measured rather than the derived quantity it
I will admit one thing: one cannot derive OUGHT by ignoring PURPOSE,
even if PURPOSE is an IS. An example of faulty reasoning should show
what I mean:
"Since foxes eat chickens alive, we ought not worry about cruelty to
hens in battery farms." Invalid: foxes' PURPOSE is to eat chickens,
they don't care about their prey. Since we are not foxes, we cannot
derive our PURPOSE from theirs.
"Since foxes eat chickens alive, and since like the fox we care only for
our short term benefit, we ought not worry about cruelty to hens in
battery farms." This is a valid moral argument, although it is not one
which many people would agree with.
"Happy and healthy hens are more productive than unhappy hens, and since
we wish for maximal productivity from our hens, so we ought to worry
about cruelty to hens in battery farms." Again, it is valid moral
"Happy and healthy hens are more productive than unhappy hens, and since
we wish for maximal productivity at minimal cost from our hens, so we
ought to worry somewhat about cruelty to hens in battery farms, but not
excessively." Again, it is valid moral argument: the profit margin is
more important to us than the welfare of the hens, but not all
important. (Of course this is a moral argument: morality does not
automatically mean 'good for others'.)
> So, given our agreed purposes, and the world being the way it is, theMany other facts are not derivable either. Why should we treat PURPOSE
> practical "ought" for tyre pressures on a given car is rigidly fixed.
> However, it stubbornly remains an "ought" rather than an "is", and it
> is not derivable from any set of facts ALONE, because "our agreed
> purposes" are an ESSENTIAL ingredient in fixing the recommended value
> of 30 pounds per square inch. If our purposes change, then that value
> changes too. For example, if the car is to be driven heavily laden,
> the pressure should be higher. If the car is to be driven over soft
> sand dunes, the pressure should be lower.
as any different from them and imbue it with mystical meaning it
The argument about IS and OUGHT is a brouhaha over nothing, but there is
a good reason for it. People have a tendency to hide the PURPOSE in
their moral arguments. This is especially great amongst those who
(rightly or wrongly) suspect that their PURPOSE would not be popular if
it were articulated.
"Just as ants know their station in life and are content, so the working
classes should be content with their station in life and stop aspiring
to become upper class [since otherwise I might lose my privileged
position in society and become a worker myself]."
If people don't explain their own PURPOSES, we can hardly be blamed if
we guess wrongly, can we?
> So even a completely mundane, wholly unmysterious, rigidlyPURPOSE is just a sub-class of factual statement, although with certain
> constrained "ought" cannot be derived from factual statements alone.
characteristics that make it difficult to measure objectively. This is
not an insurmountable problem: many other variables are difficult to
> And so to morality, which philosophers generally do not distinguishNot so. If it were true that everybody in the world, living or dead,
> from ethics, and which is about how people OUGHT to behave, NOT with
> how they ACTUALLY DO behave...
> Because people are complicated, and because there is a very wide
> range of human desiderata, and because we disagree with each other,
> the "ought"s of morality are somewhat murky. But even if there were
> no disagreement, and the "ought"s of morality were as rigidly
> constrained as the "ought"s of tyre pressure, they would strictly
> remain "ought"s rather than statements of brute fact.
agreed that (say) battery hens should be looked after to the best
extent possible, that the well-being of the hens should be put ahead of
profits, then it would be an OBJECTIVE FACT that the welfare of hens
comes ahead of profits and convenience and cheap eggs, and therefore
battery farms would not exist.
The difficulty with morality is that, because so often our PURPOSES
remain hidden (even to us) we are reduced to arguing from incomplete
premises. Hidden PURPOSES often include such factors as "I am
frightened by changed, and I don't wish to be frightened", "I wish to
tell others how to run their life", "I don't care about the suffering
of others", "It makes me happy to see others happy, and I like to be
happy", and so forth.
It might be argued that PURPOSE isn't an IS because PURPOSES are inside
our brains, while ISes are part of the objective world. But our brain
is itself part of the objective world, so how is it possible that
something inside our brain is not?
It certainly is true that (unlike the Martian) we cannot, and possible
never will be able to, derive PURPOSE from the structure of a specific
brain. But we *can* derive PURPOSE from either subject's words ("I want
to drive my car efficiently, without ruining the tyres") or their
actions. (There are sources of error in both methods: people lie, and
people act irrationally. I will consider this a flaw when you
demonstrate any other science that has eliminated all sources of
error.) If we accept that the subject is neither fooling themselves,
nor lying to us, then their stated PURPOSE is as real as are cars and
roads and pressure gauges.
> There isn't a hope in hell of anyone ever deriving any sort of(1) Since it IS a fact that argumentative writers always wish to be
> "ought" from "is"s alone, and anyone tempted to think otherwise has
> utterly failed to grasp something quite simple.
(2) and since it IS a fact that making sweeping claims without thinking
them through often leads to error;
(3) and since it IS a fact that error in one's argument proves that
one's argument is wrong;
(4) then argumentative writers OUGHT not make sweeping claims without
thinking them through.
(1) through (3) are ISes, and two of them are testable facts. (1) can be
disproven if you meet an argumentative writer who doesn't mind being
proven wrong. (2) is subject to statistical analysis by counting the
number of sweeping claims made without thinking through that lead to
error and comparing them to the number that did not lead to error. And
(3) is a tautology (by definition, an argument is wrong if it contains
Then (4) (an OUGHT) is derived from ISes alone, and is subject to
- George Parrish wrote:
> How is the tire pressure ought--Trial and error (with "feedback", correction, etc.) is a very effective
> determined? Experience with whatever
> the tire pressure is influences the ought
> by feedback. Echoes of ought and is
> eventually converge at an appropriate
> point. Understanding how that happens
> is similar to understanding which came
> first, the chicken or the egg.
method of arriving at facts such as: "30 ppsi optimises grip over the most
typical range of road surfaces".
Armed with this fact, PLUS some other assumptions that usually "go without
saying", we would normally resolve to keep the tyres at a pressure of
30ppsi. We might express our resolve by saying: "The tyres ought to be kept
at a pressure of 30 ppsi".
What are those other assumptions that normally "go without saying"? Spelled
out explicitly, the whole "argument" might go something like this:
1. The car runs best when the tyres are kept at a pressure of 30ppsi
2. We want the car to run at its best
3. We ought to do whatever helps achieve what we want
Therefore, we ought to keep the tyres at 30 ppsi
This "argument" just spells out in detail what is already blindingly
obvious -- its only real virtue is that it makes things EXPLICIT:
Premise 1 expresses an empirical fact about the car and the typical road,
discovered by trial and error ("feedback", etc.) as above. (If the roads or
the car were different, then 1 would be false.)
Premise 2 expresses a psychological fact. (If we were trying to sabotage
the car, then 2 would be false.)
Premise 3 expresses what we might call the basic "ought" of practical
reason. (But there are various other kinds of "ought" -- if our interests
were not practical but moral, or aesthetic, or prudential, or
self-destructive, or whatever, then we wouldn't accept 3.)
Each of the premises 1-3 is ESSENTIAL. 1 and 2 are "is"s in that they
describe facts. But 3 is an "ought", and the conclusion RELIES on it.
Hume's complaint was that in the context of moral reasoning, too many
writers blithely skip to an "ought" conclusion without acknowledging their
reliance on a prior "ought" -- (the equivalent of premise 3 above). This is
very important, because in moral reasoning the prior "ought" is a basic
No one disagrees about the basic "ought" of practical reason above, but we
certainly do disagree about moral principles. People are prepared to kill,
and sometimes even to die, over moral issues. It is gross negligence,
intellectually, to fail to acknowledge the basic moral principle(s) one's
"ought"s rely on. At best, it is deception of self and others.
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