Argues that to understand how writers represented ghost-seers and detectives, the views of contemporary scientists, philosophers, and spiritualists with which these writers engage have to be taken into account: these views raise questions such as whether seeing really is believing, how much of what we 'see' is actually only inferred, and whether there may be other (intuitive or spiritual) ways of seeing that enable us to perceive objects and beings inaccessible to the bodily senses.