There Are No Facts... The Dangers and Responsibility
This quote needs to go with something like this one from Heidegger to fill out its meaning:
"We never really first perceive a throng of sensations... Much closer to us than all sensations are the things themselves. We hear the door shut in the house and never hear acoustical sensations or even mere sounds."
What is the meaning of these two quotes? It is that what we take as facts are already interpretations because the physical things in themselves (the nomena as Kant calls it) are meaningless in and of themselves. Things are ideas and not the bare sensations we have or the physical objects in the world; ideas shape the sensations (our experience of the physical objects) into what we commonly call 'things.' The bare physical has qualities like weigh, size, hardness, etc. And those qualities have an impact on us, but what that impact means (especially when it comes to how we act or think) is not in the physical object; it is in the idea, in the thing.
We interpret every experience and object to make sense of it, and facts already make some sort of sense. So facts are not pure experience or data, they are already interpreted. As a result, there really are no objective facts because they are already always interpretations in so far as the have meaning, or are an idea and not just a sensation.
Pointing this out is especially important because things (including facts) come prepackaged these days. We encounter very little without mediation or packaging. A big part of that packaging is interpretation.
This is not meant to be a defense of 'alternative facts.' It is legitimate to question methods, definitions and context to try and uncover the assumptions and influences that shaped the facts and things being discusses or dealt with. This is important to do when you think there is a problem or even a disagreement in how different people experience and understand things. But it is naive to simply deny facts and offer alternatives without digging deeper.
It must always be kept in mind that reinterpreting any of these things or facts changes more than just that one thing. When you question at a fundamental level, anything that you change there has the potential to affect everything else in that network of meaning, all the other things and facts that are connected to it. Interpretation and questioning things and facts is not something to be taken lightly.
Yet, because so many intelligent people deny the fundamental role that interpretation plays in our understanding and insist that facts are self-evident, it leaves the door open to people who want to take the Nietzsche quote and use it in a superficial way simply to twist any situation to their advantage. Taking interpretation seriously and examining interpretations in a serious way (not brushing them aside as nonsense if we don't agree or understand right away) will take the power of this quote from those that simply want to find advantage by using it.
There are no facts, only interpretations... This revelation of Nietzsche's brings with it potential dangers and serious responsibility. It does not at all mean that anything goes, and we need to resist that naïve interpretation of it. It means that serious thought and attention needs to be paid to interpretation. It means that when genuine disagreement arises, facts cannot be taken as self-evident and used to quickly shut down debate. It means that differences in interpretation and perspective need to be taken seriously: discussed and explored in a genuine and intelligent way. It means the world is a more complex place than we often want to admit, and that we need to take up the responsibility that comes with that if we want to keep others from taking advantage of that.