A ghost, according to Webster‘s Ninth New Collegiate Dictionary, is:

1: the seat of life or intelligence: SOUL <give up the ~> 2: a disembodied soul; esp: the soul of a dead person believed to be an inhabitant of the unseen world or to appear to the living in bodily likeness 3: SPIRIT, DEMON 4: a: a faint shadowy trace <a ~ of a smile> b:  the least bit : IOTA <didn’t have a ~ of a chance> 5:  a false image in a photgraphic negative or on a television screen caused esp. by a reflection 6:  one who ghostwrites 7:  a red blood cell that has lost its hemoglobin — ghost•like adj — ghosty adj

A ghost, then, is something not tangible, though it may have tangible causes, as in the case of reflections on a photographic negative or a television screen. Ghosts are the intangibles of this world produced, at some point, by tangible causes.

I think, for example, of political ideology, not necessarily the ideology we mean when we think of Althusser or Eagleton, but possibly. Political ideology has tangible causes. For example, North American political ideology identifies dissenters within oppressive Middle Eastern nations as terrorists, a term that delivers both emotional and political freight. The possiblity that such dissenters are themselves violent and oppressive is, not to be pushy about it, immaterial. The political struggles of Arab people are framed as unreasonable and arbitrary bids for power rather than as political acts motivated by historical and social forces. This dismissive attitude is fueled, ironically, by a lack of fuel.

Some North Americans tend to think negatively of Arabs. Many times, such prejudice is the result of a psychological association between North Americans’ paralyzing depedence on Arab nations for oil and the false perception that the United States and, by extension, its citizens are the rightful rulers of the world. A conflict arises between Americans’ sense of self-importance and their humiliating dependence on the cooperation of a foreign power. This discrepancy is annealed by ideology (definitely the realm of Althusser), which produces a psychological negation whose function is to diminish the significance of the foreign powers in question: Arabs are oppressive and their political struggles chaos. North American anti-Arab propaganda is an ideological response to an ego-deflating material dependence on oil. A material condition produces an ideological reaction, produces a ghost.

Some ghosts are produced by other ghosts. Some ghosts produce objects in a way similar to how the body without organs produces by breaking flows.

In the current example, the ghost of anti-Arab sentiment leads to bombing runs on Iraq, an activity that at once continues the conditions of US dependency and enables the US to lash out at the spectral threat of the Arab.