  We develop a modal logic to capture partial awareness. The logic has three
building blocks: objects, properties, and concepts. Properties are unary
predicates on objects; concepts are Boolean combinations of properties. We take
an agent to be partially aware of a concept if she is aware of the concept
without being aware of the properties that define it. The logic allows for
quantification over objects and properties, so that the agent can reason about
her own unawareness. We then apply the logic to contracts, which we view as
syntactic objects that dictate outcomes based on the truth of formulas. We show
that when agents are unaware of some relevant properties, referencing concepts
that agents are only partially aware of can improve welfare.
