Compartmentalization can refer to two different things; compartmentalization and "doublethink".
The term "compartmentalization" refers to the practice of behaving a certain way under certain circumstances and behaving the exact opposite at all other times. An example would be a geologist who studies the age of the earth. When he's at his job he believes that the earth is 4.55 billion years old in order for the evidence he finds to make sense. However, when he goes to church he might temporarily reject his beliefs and believe that the earth is 6,000 years old instead while he's at worship. After church is over, though, he returns to his job and his belief a 4.55 billion year old earth returns as well. Obviously one can't believe in both an old and a young earth simultaneously, but the geologist does because the two aspects of his life require the difference in beliefs.
"Doublethink" comes from George Orwell's novel Nineteen Eighty-Four, where it is defined as:
- "...the power of holding two contradictory beliefs in one's mind simultaneously, and accepting both of them."
For example, the Creationist speaker Kent Hovind often states that the geological column is simply the result of the Noachian Flood. Yet he also claims that the geological column is fiction created by scientists, one which doesn't really exist. The contradiction is obvious: either the geological column exists or it doesn't. A clearer example is his common statement that no scientist dares to speak out against evolutionary "dogma"; yet he also provides quotes of scientists "admitting" that evolution is wrong.
- Doublethink at kent-hovind.com