By the end of the nineteenth century, a new perspectivism (or some would say a relativism) had come into philosophy. Friedrich Nietzsche, in particular, had argued that all knowledge is perspectival and that philosophy could not be reduced to a single perspective, that philosophy might be relative to a people, or to our particular species, or even to individual psychology. Husserl's contemporary Wilhelm Dilthey defended a milder but similar thesis, and the "sociology of knowledge" was just beginning its ascension.
Plato and Aristotle...had to account for the existence of scientific knowledge, that is knowledge that could not be different than it is, that is unchanging, in the face of the Hericlitean problem that the world of experience is constantly changing. The problem that Husserl was faced with is the Humean problem, that knowledge can only be of relations of ideas in the mind and can never be of facs. The Kantian explanation that we can learn about things in the world by applying a-priori categories to them, but we could never be sure we are right, was not a science in the sense that Husserl was trying to develop...therefore this explanation of "nature" was an explanation of what knowledge of the existence of corporeal entities means.
Natural objects, for example, must be experienced before any theorizing about them can occur.
We would be in a nasty position indeed if empirical science were the only kind of science possible
Husserl received a decisive impetus from Brentano and from his circle of students. The spirit of the Enlightenment, with its religious tolerance and its quest for a rational philosophy, was very much alive in this circle. Husserl’s striving for a more strictly rational foundation found its corroboration here. From the outset, such a foundation meant for him not only a theoretical act but the moral meaning of responsibility in the sense of ethical autonomy
Husserl argued that the study of consciousness must actually be very different from the study of nature. For him, phenomenology does not proceed from the collection of large amounts of data and to a general theory beyond the data itself, as in the scientific method of induction. Rather, it aims to look at particular examples without theoretical presuppositions (such as the phenomena of intentionality, of love, of two hands touching each other, and so forth), before then discerning what is essential and necessary to these experiences.
Phenomenology can be roughly described as the sustained attempt to describe experiences (and the “things themselves”) without metaphysical and theoretical speculations. Husserl suggested that only by suspending or bracketing away the “natural attitude” could philosophy becomes its own distinctive and rigorous science, and he insisted that phenomenology is a science of consciousness rather than of empirical things. Indeed, in Husserl’s hands phenomenology began as a critique of both psychologism and naturalism.
The years of his teaching in Halle (1887–1901) were later seen by Husserl to have been his most difficult. He often doubted his ability as a philosopher and believed he would have to give up his occupation. The problem of uniting a psychological analysis of consciousness with a philosophical grounding of formal mathematics and logic seemed insoluble. But from this crisis there emerged the insight that the philosophical grounding of logic and mathematics must commence with an analysis of the experience that lies before all formal thinking
As a philosopher with a mathematical background, Husserl was interested in developing a general theory of inferential systems, which (following Bolzano) he conceived of as a theory of science, on the ground that every science (including mathematics) can be looked upon as a system of propositions that are interconnected by a set of inferential relations. Following John S. Mill, he argues in Logical Investigations that the best way to study the nature of such propositional systems is to start with their linguistic manifestations, i.e., (sets of) sentences and (assertive) utterances thereof.
Edmund Husserl was the principal founder of phenomenology—and thus one of the most influential philosophers of the 20th century. He has made important contributions to almost all areas of philosophy and anticipated central ideas of its neighbouring disciplines such as linguistics, sociology and cognitive psychology.