The quote "It is still open to discussion whether psychology is a natural science or it can be regarded as at all" does not have a definitive author. This is because it's a common sentiment expressed by various philosophers and scientists throughout the history of psychology.

The question of whether psychology is a natural science has been a subject of ongoing debate for decades. Some argue that psychology should be considered a natural science, while others believe it is more closely aligned with the humanities or social sciences.

Here are some reasons why the quote might be attributed to various individuals:

* It is a widely held view: The sentiment expressed in the quote reflects a common skepticism about the scientific rigor of psychology, particularly in its early stages.

* No single figure owns this debate: Many philosophers and scientists have contributed to the discussion about the nature of psychology, making it difficult to pinpoint a single source.

* The quote could be a summary of a broader argument: It might be a concise expression of an opinion found within a larger philosophical or scientific text.

If you are interested in learning more about this topic, you can explore the works of prominent figures in psychology, philosophy of science, and the history of psychology. Some key figures to consider include:

* Wilhelm Wundt: One of the founders of experimental psychology.

* John B. Watson: A pioneer of behaviorism.

* Carl Jung: A prominent psychoanalyst.

* B.F. Skinner: A leading figure in behaviorism.

* Noam Chomsky: A linguist and cognitive scientist.

By exploring the works of these and other influential individuals, you can gain a deeper understanding of the ongoing debate surrounding the nature of psychology.