Intentionality is that property of many mental states and events by which they are directed at or about or of objects and states of affairs in the world" (ibid.
The key concept was that of possible world - a concept introduced implicitly by Rudolf Carnap (esp. 1957; under the name of state of affairs) and explicitly by Saul Kripke (1963).
But, as I am of a disposition that makes me unwilling to be esteemed different from what I really am, I thought it necessary to endeavor by all means to render myself worthy of the reputation accorded to me; and it is now exactly eight years since this desire constrained me to remove from all those places where interruption from any of my acquaintances was possible, and betake myself to this country, in which the long duration of the war has led to the establishment of such discipline, that the armies maintained seem to be of use only in enabling the inhabitants to enjoy more securely the blessings of peace and where, in the midst of a great crowd actively engaged in business, and more careful of their own affairs than curious about those of others, I have been enabled to live without being deprived of any of the conveniences to be had in the most populous cities, and yet as solitary and as retired as in the midst of the most remote deserts.
This is a possible state of affairs.
I find it useful to characterize beliefs as having the mind-to-world direction of fit (the belief in the mind is supposed to fit the state of affairs in the world) and desires and intentions as having the world-to-mind direction of fit (if all goes well with the desires and intentions, the world comes to fit how it is represented in the mind).
It is also possible to imagine a language that does not allow reference to objects, but only to processes as states of affairs.
The paradox I mentioned earlier is that the unit necessarily represented by an intentional state is a whole state of affairs, not an object.
Yet perceptually objects and not states of affairs are phenomenologically salient.
We need to distinguish between those communicative acts that involve intentionally representing a state of affairs in the world and those that simply express (in the original sense of pressing out, of giving vent to) an animal’s internal state, where that expression may convey information about the world but it does not do so by representing that something is the case, or by representing other sorts of conditions of satisfaction.
If I say “Ouch” when I am not in pain I may mislead and misinform, but I do not lie. 9 So the first thing our hominids have to create are some conventional devices for representing the same states of affairs in the world that their existing intentional states represent.