Classical logic deals with truth values, while modal logic deals with possibilities.

Classical logic is deductive, while modal logic is inductive.

Classical logic is concerned with the relationship between premises and conclusions, while modal logic is concerned with the relationship between possible worlds.

Classical logic is based on the law of the excluded middle, while modal logic is based on the law of non-contradiction.

A possible world is a complete and consistent description of how the world could be.

A possible world is a world that is actually the case.

A possible world is a world that is logically impossible.

A possible world is a world that is physically impossible.

A statement is necessary if it is true in all possible worlds.

A statement is necessary if it is true in some possible worlds.

A statement is necessary if it is false in all possible worlds.

A statement is necessary if it is false in some possible worlds.

A statement is possible if it is true in at least one possible world.

A statement is possible if it is false in all possible worlds.

A statement is possible if it is true in some possible worlds and false in others.

A statement is possible if it is false in some possible worlds and true in others.

A statement is contingent if it is true in some possible worlds and false in others.

A statement is contingent if it is true in all possible worlds.

A statement is contingent if it is false in all possible worlds.

A statement is contingent if it is true in some possible worlds and false in others.

Modal logic is used to analyze the logical structure of scientific theories.

Modal logic is used to develop new scientific theories.

Modal logic is used to test the validity of scientific experiments.

Modal logic is used to communicate scientific findings.

Modal logic is used to analyze the concepts of possibility and necessity in science.

Modal logic is used to develop new scientific theories.

Modal logic is used to test the validity of scientific experiments.

Modal logic is used to communicate scientific findings.

Modal logic is only able to deal with a finite number of possible worlds.

Modal logic is not able to deal with the concept of time.

Modal logic is not able to deal with the concept of change.

All of the above.

The problem of finding a complete and decidable modal logic.

The problem of developing a modal logic that can deal with the concept of time.

The problem of developing a modal logic that can deal with the concept of change.

All of the above.

Developing new modal logics that can deal with a wider range of concepts.

Applying modal logic to new areas of philosophy and science.

Using modal logic to develop new tools for artificial intelligence.

All of the above.