I am interested in B. Russell's quote:
Science is what we know; philosophy is what we don't know.
What is he saying here in terms of a definition of philosophy? In his sense, is that correct to say that philosophy cannot give us more knowledge except for better organizing and explaining our ignorance?
"A man might say, with enough truth to justify a joke: 'Science is what we know, and philosophy is what we don’t know.'"
-Bertrand Russell
“Philosophy for Laymen”
Universities Quarterly 1 (Nov 1946), 38-49
Unpopular Essays, Chapter 2 (George Allen & Unwin, 1951)
No, philosophy is not taxonomy. Philosophy is respect for obtaining knowledge - whether this be where there is ignorance and false arguments duly rejected, or, advancing hypotheses and the means by which to do so. As the term has translated from the Greek through the Latin, philosophy is "love of wisdom".
Note that the quote above is from his later years of writing and in particular from a chapter called, "Philosophy for Laymen". Consider the following quote from his introduction to The History Of Western Philosophy:
"Science tells us what we can know, but what we can know is little, and if we forget how much we cannot know we become insensitive to many things of very great importance. Theology, on the other hand, induces a dogmatic belief that we have knowledge where in fact we have ignorance, and by doing so generates a kind of impertinent insolence towards the universe. Uncertainty, in the presence of vivid hopes and fears, is painful, but must be endured if we wish to live without the support of comforting fairy tales. It is not good either to forget the questions that philosophy asks, or to persuade ourselves that we have found indubitable answers to them. To teach how to live without certainty, and yet without being paralyzed by hesitation, is perhaps the chief thing that philosophy, in our age, can still do for those who study it."
I think it quite likely that he's saying exactly that. Russell, pretty much from 1905 on and more so in later life, considered that knowledge derived from only two sources; facts about objects (derived from the scientific method) and certain facts about ourselves (really a special class of object, which, by direct acquaintance we already know and have no need to verify independently.
His philosophy centred around better describing these facts about ourselves, such as logic and ethics so that apparent false conclusions and conflicts would dissolve. In that sense, it was not his intention to give us more knowledge by philosophy, but to better describe the knowledge we have (and knowledge we cannot, or do not have).
In fact From Russell's view of the sources of knowledge, philosophy could not possibly advance new knowledge, he says of truths there are "...those which merely state what is given in sense, and also certain abstract logical and arithmetical principles, and (though with less certainty) some ethical propositions”.
In The impact of Science on Society he states that "...Science, ever since the time of the Arabs, has had two functions: (1) to enable us to know things..." and in My Philosophical Development "I still think that truth depends upon a relation to fact, and that facts in general are nonhuman"
I think the failure of Russell's work on the foundation of Mathematics made him much more skeptical even of the second type of intuitive knowledge, leading him to statements like the one you've found.
@Mr.Kennedy has made a good answer.
And @Issacson objection that
etymology ≠ definition
is true in general. However I believe in this case
etymology+history = definition
is viable at least in approximation.
In Socrates time what we (today) call philosophers were called sophists. Socrates – very much a sophist by the standards of his day – did not like their...
So he suggested the element of love – philos – be conjoined to sophia – knowledge. The fact that Socrates could die for his convictions put the seal on his loving conviction. And the term stuck.
2500 years is a long time...
And most practitioners have not just not shown the passion of Socrates they've even forgotten that it was the distinguishing feature.
Ideally therefore, if we follow Socrates(Plato) not just in detail but in intent, philosophers should be called sophists and their profession sophistry when love is absent.
This is a general, and relatively common way of conceptualizing the difference between science and philosophy. Science deals with well-defined topics within already established structures, that is why it is about "what we know." Of course, we discover new results within science all the time, but we know what we are looking for, and we know what we expect (which is why we know when results depart from expectations).
Philosophers are comfortable much further out from shore on the conceptual ocean. Philosophical ideas don't have the structural support that scientific ideas have, they are about topics we haven't tamed yet, thus "what we don't know." For example, after all this time, we still don't really know why one person likes one piece of art, and another person hates it. We have plenty of theories, and we've noted some correlations, but the topic of aesthetics is still essentially philosophical and speculative. If we ever understand it to the point where we can confidently and consistently predict it, it will have become a science.
Thus, it's not the case that philosophy solely organizes ignorance, or that it is incapable of expanding knowledge, it's that it does not expand knowledge systematically, like science. Every scientist, however, was preceded by a philosopher.
