For the philosophical debate one of the most important conclusions of Giesbers's research into the group of realists around 1800 are that rationality does not exist without an individual who has a practical engagement with his surroundings. In this sense, rationality can only be understood as an applied rationality, in which we determine with which means and with what actions we can best achieve our goals (this is the case for needs as well as in ethics).
The uncertainty of being real
Furthermore he finds that as important as it is to realise that our experiential world is understood from our perspective as an individual, there is no way to prove from this that we exist, that we are real. There is therefore always a core of our existence that remains outside of our experience and our reflection alike. The way in which this core remains outside of our experience is also the way in which we are free. After all, there is no way in which this core can be influenced.
The above views have far-reaching consequences for philosophy. It is not the task of philosophy to offer an insight into something that we do not already experience or reflect on. Philosophy only describes what we already perceive and reflect on. For many of the realists it is the task of philosophy to understand where our ability to conceive of something ends and what then remains inconceivable (our existence, reality).
Nature and history of philosophy
Partly the realists are society's reaction to the pretensions of the philosophers. In addition to this, the realists generally produce avenues of reasoning that adhere to the standards of philosophical argumentation, such as coherence and depth. It is then not surprising that some of these avenues of reasoning were adopted by the idealists and as such became part of the established discourse. The realists also introduced the question about the nature of philosophy into this discourse, at a time when many sciences were being emancipated from the philosophical faculty. In this they made important contributions to the immense complexity of this period in the history of philosophy.