This image illustrated by Dunne and Raby is a symbolic reference to the possibilities of ones future.
The concept functions as a listing of possible things that can happen based on the now and this strongly applies to the theory of design fiction.
Lets start with the most obvious outcome. the probable.
The probable is the representation for the outcome which is the most likely to happen,given the present situation. as tine passes, the probable shape will always remain narrow because that is the future that the current series of events is leaning towards. without leaving much room for other possibilities along the way.
Next is, the preferable. the preferable functions in quite a similar way to that of the probable, which a similar shape arc as time progresses from the present, to the future. However, the preferable is speculating the boundaries which it can cross into, as seen from the image. the plausible shape can lean into unknown possibilities as it proves as a way to “think outside the box”. despite this, it will always remain connected to the probable, due to the realization of the present. if the preferable loses its sense of reality from the present, then it becomes the plausible.
The plausible is a state that has just left the restrictive boundaries of probable and preferable, being able to be more flexible with the present. However, realism will be somewhat at a loss in terms of the future. With the plausible, it would be hard to see what the future holds for it because it is not as centered as the others. in addition, it has a large radius,which translates to the scale of possible outcomes or futures. this leads us to the final aspect of this diagram. the possible.
The possible is mostly seen as a speculation from the present due to its larger radius and scope. this means that the restrictions and limitations of the present are lifted , resulting in the future being literally possible of any outcome.
Really puts things into perspective when it comes to designing world concepts.