Seminal French existentialist philosopher Jean-Paul Sartre relates phenomenology, consciousness and intentionality to a theory of imagination that departs radically from prior conceptions in psychology.
In the image, indeed, a certain consciousness gives itself a certain object. The object is therefore correlative with a certain synthetic act, which includes among its structures a certain knowledge and a certain ‘intention’. The intention is at the centre of consciousness: it is the intention that aims at the object, which is to say, that constitutes it for what it is. The knowledge, which is indissolubly linked to the intention, specifies that the object is such or such, adds determinations synthetically. To constitute as an image in oneself a certain consciousness of the table is at the same time to constitute the table as an object of imaging consciousness. The object as imaged is therefore contemporary with the consciousness that I have of it and it is exactly determined by that consciousness: it includes in itself nothing but what I am conscious of; but, inversely, everything that constitutes my consciousness finds its correlate in the object. My knowledge is nothing other than knowledge of the object, knowledge concerning the object. In the act of consciousness, the representative element and the knowledge element are linked in a synthetic act. The correlative object of this act is therefore constituted as a concrete, sensible object and at the same time as an object of knowledge. This results in the paradoxical consequence that the object is present for us externally and internally at the same time. Externally, because we observe it; internally, because it is in it that we observe what it is. This is why extremely poor and truncated images, reduced to a few spatial determinations, can have a rich and profound sense for me. And this sense is there, immediate, in these lines, it is given without a need to decipher it. This is also why the world of images is a world where nothing happens. I can easily, at my liking, move such-and-such an object as imaged, turn a cube, make a plant grow, make a horse run, there will be never the smallest time-lag between the object and the consciousness. …
I will call the different immediate modes of apprehension of the real as a world ‘situations’. We can then say that the essential condition for a consciousness to imagine is that it be ‘situated in the world’ or more briefly that it ‘be-in-the-world’. It is the situation-in-the-world, grasped as a concrete and individual reality of consciousness, that is the motivation for the constitution of any irreal object whatever and the nature of that irreal object is circumscribed by this motivation. Thus the situation of consciousness must appear not as a pure and abstract condition of possibility for all of the imaginary, but as the concrete and precise motivation for the appearance of a certain particular imaginary.
From this point of view, we can finally grasp the connection of the irreal to the real. First of all, even if no image is produced at the moment, every apprehension of the real as a world tends of its own accord to end up with the production of irreal objects since it is always, in a sense, free nihilation of the world and this always from a particular point of view. So, if consciousness is free, the noematic correlate of its freedom should be the world that carries in itself its possibility of negation, at each moment and from each point of view, by means of an image, even while the image must as yet be constituted by a particular intention of consciousness. But, reciprocally, an image, being a negation of the world from a particular point of view, can appear,, only-on- the ground of the world and in connection with that ground. Of course, the appearance of the image requires that the particular perceptions be diluted in the syncretic wholeness world and that this whole withdraws. But it is precisely the withdrawal of the whole that constitutes it as ground, that ground on which the irreal form must stand out. So although, by means of the production of the irreal, consciousness can momentarily appear delivered from its ‘being-in-the-world’, on the contrary this ‘being-in-the-world’ is the necessary condition of imagination.