“Philosophy … is a science, and as such has no articles of faith; accordingly, in it nothing can be assumed as existing except what is either positively given empirically, or demonstrated through indubitable conclusions.”

ibid, p. 28
Following Cerebus (2004-)

Source: 1790s, The Age of Reason, Part II (1795), Chapter III: Conclusion.
Context: The study of theology as it stands in Christian churches, is the study of nothing; it is founded on nothing; it rests on no principles; it proceeds by no authorities; it has no data; it can demonstrate nothing; and admits of no conclusion. Not any thing can be studied as a science without our being in possession of the principles upon which it is founded; and as this is not the case with Christian theology, it is therefore the study of nothing.

Terry Winograd and Fernando Flores in Understanding Computers and Cognition : A New Foundation for Design (1986)
Misattributed

Vol. VIII, p. 148
Joannis Kepleri Astronomi Opera Omnia, ed. Christian Frisch (1858)

Source: Faith vs. Fact (2015), p. 258

Source: Knowledge and Human Interests, 1971, p. 4

Book 1, sec. 55 (10 June 1887) http://nietzsche.holtof.com/Nietzsche_the_will_to_power/the_will_to_power_book_I.htm
The Will to Power (1888)

[O] : Introduction, 0.6
Semiotics and the Philosophy of Language (1984)
Context: When semiotics posits such concepts as 'sign', it does not act like a science; it acts like philosophy when it posits such abstractions as subject, good and evil, truth or revolution. Now, a philosophy is not a science, because its assertions cannot be empirically tested … Philosophical entities exist only insofar as they have been philosophically posited. Outside their philosophical framework, the empirical data that a philosophy organizes lose every possible unity and cohesion.
To walk, to make love, to sleep, to refrain from doing something, to give food to someone else, to eat roast beef on Friday — each is either a physical event or the absence of a physical event, or a relation between two or more physical events. However, each becomes an instance of good, bad, or neutral behavior within a given philosophical framework. Outside such a framework, to eat roast beef is radically different from making love, and making love is always the same sort of activity independent of the legal status of the partners. From a given philosophical point of view, both to eat roast beef on Friday and to make love to x can become instances of 'sin', whereas both to give food to someone and to make love to у can become instances of virtuous action.
Good or bad are theoretical stipulations according to which, by a philosophical decision, many scattered instances of the most different facts or acts become the same thing. It is interesting to remark that also the notions of 'object', 'phenomenon', or 'natural kind', as used by the natural sciences, share the same philosophical nature. This is certainly not the case of specific semiotics or of a human science such as cultural anthropology.

What then must we do? (1886)