Welcome to Scientific Method. I have provided on this web space the material I presented to you in the first seminar on Ayers.

Each week, one of you will present a chosen paper to the group. Although you are free to present your own designated papers in any format you wish, I provided this material as a model for those who want some guidance.

When critically analysing a paper, start with what the paper is trying to do. What is the aim of the paper, its contents, its arguments. Last but not least, don't forget to tell us what you think.

Ayers: What is a Law of Nature?

‘Epistemology’ and Laws

• Laws encourage respect for science

• Basis for prediction, inference and explanation/justification of claims to knowledge

• Laws of nature describe important facts about reality

• ‘Regularity theory’ says they give descriptive summaries of how things will behave now and in the future on the basis of past observation

• Is this equivalent to telling us how things MUST behave?

• If necessity is to be found, do we discover it by experience or by rational deduction?

The simple regularity theory of laws & Humean thought

-Ayer suggests Hume’s observations on causation are structurally similar to the make up of the regularity theory

-Observe 'constant conjunctions' of A-B

-a as a matter of empirical fact is followed by b, therefore we say a causes b

-but no objective necessity is ‘out there’ in the objects/events themselves…..

-a doesn’t make b occur

-there is no ‘logical’ necessity between the two events (to be found using reason): no a priori deduction of A’s being invariably associated with B’s

-Indeed its logically possible that a B wouldn’t follow an A.

-there is also no ‘non-logical’ necessity between the two events (to be found using sense experience), when two objects collide we see a series of consecutive motions, not an impression of causal necessity

-So….we now understand the structure of the simple regularity theory:

- laws of nature are no more than true universal generalisations, whose components are not necessarily connected. The objective content of a law of nature is exhausted in facts about the world, observed conjunctions

-Our laws tell us what happens in certain empirical conditions, but not what must happen.

For Ayers, this ‘simple’ theory needs work…

‘Avoiding vacuous laws’

All V’s are A’s =(same as) It is false that there is a V that is not a A

We say the law ‘all V’s are A’s’ is true iff:

i) (x)(Vx then Ax)

ii) ~(singular x)(Vx & ~Ax) (~ means no, or none)

But: what if there are no V’s in world?

(ii)becomes true automatically (can’t find an exception) but then as a result so does all V’s are A’s.

So? we have an ‘empty’ law

As useful as the ‘law’ all dragons eat cheese…

Solution: Add existential condition: ‘a law is a true universal generalisation provided there actually are objects satisfying the generalisation’

‘What about noninstantial laws?’

The objects of laws may well exist, but laws can be made about situations that people haven't experienced.

i.e. Newtonian inertia (first law)

Solution: Derivative ‘v’ ultimate laws.

These noninstantial laws are simply derivative from instantial ones, with an ‘added supposition’

-Newtonian inertia derived from ultimate/instantial second law (a=f/m) (added supposition? that no force acts, therefore we get no acceleration, inertia)

‘Forever missing values’

Functional laws assert functional relations betwen variables

Increase the temperature, the pressure of a gas rises. What about 1 million degrees?

Infinite range of variables but finite range of empirical application

Can we reconcile the counterfactual conditionals that result (if p were to happen then q, where we will never see p) with the fact that these laws are also descriptions of what is actually happening in the world.

Solution? none is obvious....

‘Can we even tell if its a law or an accidental generalisation?’

Commonalities true by circumstance or coincidences of the past aren’t laws.

Say all dogs born at sea have always been spaniels. We don't expect a pregnant rottweiler to produce a spaniel if she gives birth at sea do we??

Whats happened? we overrule an accidental generalisation with a more important law of heredity or biology.

Problem is, the simple regularity theory as it stands cannot say why we respect one more than the other.

Solution? Ayers Epistemic Regularity Theory

Involves a role for beliefs or epistemic attitudes of a subject

After all, we obviously can distinguish the genuine laws

So.. ‘laws are true universal generalisations but there are conditions to what we believe to be a law which also govern how we apply or understand them.

* The big question is…. Has Ayers done enough? *

Have we answered the missing values problem?

Have we given any substantive account of what the necessary features of a law are?