Why do laws explain?

• Laws are universal statements of the form• “All a’s are b’s,” • “Whenever an event of type C occurs, an event of type E occurs,” • “If (an) event e happens, then invariably, (an) event f occurs.”

• They don’t refer to particular objects, places or times, implicitly or explicitly, but to abstract relations between things.

What is the difference?

• If an electric current is applied to a sample of iron under standard temperature and pressure, then the sample conducts the current.• All bachelors are unmarried men.

What is the difference?

• If an electric current is applied to a sample of iron under standard temperature and pressure, then the sample conducts the current.• All bachelors are unmarried men.

• Laws explain because laws have some sort of necessity.

What is the difference?

• All solid spherical masses of pure plutonium weigh less than 100,000 kilograms.• All solid spherical masses of pure gold weigh less than 100,000

kilograms.

What is the difference?

• All solid spherical masses of pure plutonium weigh less than 100,000 kilograms.• All solid spherical masses of pure gold weigh less than 100,000

kilograms.• Real laws vs. Accidental generalizations• the universal truth about plutonium supports the plutonium

counterfactual, while the universal truth about gold masses does not support the gold counterfactual.

Counterfactuals

• A counterfactual is another sort of if/then statement, one expressed in the subjunctive tense, instead of the indicative tense in which laws are expressed.• These are in the form of ¬q→¬p• We employ such statements often in every day life: “If I had not

known you were coming, I would have not baked a cake.”• Logically equivalent to I baked the cake, because I knew you were coming.

• Laws support their counterfactuals, while accidental generalizations do not.

The circularity of founding explanation on physical laws. • It’s no explanation of the necessity of laws to say they reflect

“physical” or “natural” or even better “nomological” (from nomos, Greek for law) instead of logical necessity.

• natural or physical necessity consists in, then grounding the necessity of laws on physical or natural necessity, is grounding the necessity of laws on itself!

Counterfactuals and Causation

• For nomological necessity just turns out to be the same thing as the necessity that connects causes and their effects• Eg. Billiard ball

Counterfactuals and Causation

• For nomological necessity just turns out to be the same thing as the necessity that connects causes and their effects• Eg. Billiard ball

• If we cannot observe or detect or even conceive of what the necessary connection between individual instances of causes and their effects might be, the prospect for giving an account of how causal explanation works or why laws have explanatory force weakens.

Different kinds of necessity

• “ontology”—a list of the kinds of things there are in reality, other such objects may have to be accepted• sentence in any language expresses a law if it expresses a proposition

of universal form that is either an axiom or a theorem in all of the deductive systems of propositions that are tied for being the best combination of simplicity and strength in describing all the local matters of particular fact in the history of the universe

Different kinds of necessity

• “ontology”—a list of the kinds of things there are in reality, other such objects may have to be accepted• sentence in any language expresses a law if it expresses a proposition

of universal form that is either an axiom or a theorem in all of the deductive systems of propositions that are tied for being the best combination of simplicity and strength in describing all the local matters of particular fact in the history of the universe• Sentences in a particular language express propositions, but are not

identical to them. Consider, “It is raining,” “Es regnet” and “Il pleut.” These are three sentences that all express the same proposition

Different kinds of necessity

Platonic Realism• Scientific laws are not between

individual instances, but between universals. • These are at the level of

propositions.• Explanations work, because

science uncovers the hidden nature of these universals

Nancy Cartwright• These philosophers dispose of the problem

of distinguishing laws from accidents by denying that there are laws in nature at all.

• the explanations provide no reason to think the “laws” they mention are true about the world.

• Everybody in the universe has certain capacities or a dispositions

• A disposition is something that an object may have even when it is not manifesting it. (e. g. glass)