Very few fields of study are ‘new’. People have been writing PhD’s and dissertations for centuries, and in the same fields that we might be interested in. How, for example, would one go about writing a new dissertation on Shakespeare? Melville? Well, the subject can be approached through a fresh perspective, and many perspectives are historically located. Finding a new method of approach can make your dissertation stand out in the crowd.
Before finding something new, we must of course know what is old. How can we decide on the latest fashion, on the newest trend, or the novel approach, if we have no knowledge of the current climate? Journals (and conferences) are the place to find the most current approaches to any given subject. Find out what has happened, what is happening, and try to identify a gap in the existing market.
Sometimes we can take a new approach that has developed in a particular historical period. For example, in the latter half of the previous century, ‘feminist’ criticism developed in many areas, and changed, dramatically, the entire academic outlook. This completely new perspective, which challenged the standard framework, was not really available before this time. Now we have things like ‘environmental criticism’, ‘eco theory’, etc. and these provide fresh readings in many discourses.
You can apply an old lens to a new field. For example, you could apply a particular kind of theoretical framework to a field in which it has never been used. By combining an existing theoretical framework with a new field, you create a unique combination.
Finally, think about making new connections within existing fields. For example, you could integrate various findings in contemporary neuroscience; the individual studies might already exist, but you can forge a bridge between them, and by so doing can create a new perspective, and can extrapolate novel findings from this.
A PhD needs to do two things; it needs to offer something novel, a new approach, whilst also being a sensible, conventional addition to an existing field. Finding the perfect balance between these can be tricky, but taking the time to do it can make all the difference to the reception of your work.