I don't want this to be a long post, but Rose sent me this, which people should watch. Then I'll add some comments.
OK, I hope you enjoyed that.
So the question I want to address is, "How can you be a relativist?" Because, as the video says, there is knowledge. You don't walk out the second floor window, and we can extend our lifespans with medicine, and all that. It's not all a big mystery, and it's not all "anything goes."
Quite right. There is knowledge, and it's not all "anything goes." But it does not follow that relativism is false.
Listen to the video carefully. As it says, science is the willingness to change our views based on the evidence. If you can show us how homeopathy works, and how it works, says the author, I'll go running down the street shouting "It's a miracle."
To the scientists, to the empiricist, to the reasonable person, beliefs are based, through reason, on the evidence. It is precisely the mark of the unreasonable, of the unscientific, that they will not change their beliefs even in the face of evidence, that their 'knowledge' is constant, unchanging.
One should ask, rather, how can someone be an empiricist, how can someone base their beliefs and knowledge on the evidence, and not be a relativist? If one's own belefs and knowledge might change from time to time, why is it not reasonable to suppose that others' might as well?
Indeed, it is pretty evident that each of us has his or her own distinct set of experiences. A very different body of evidence on which to base their knowledge and beliefs. It would be a miracle were it to turn out that everyone's knowledge and beliefs were the same!
Yes, it may be argued that there is an element of commonality to people's knowledge, that the world is the same world for everyone, and that we go to great effort, through scientific method and repeatable, testable, experimentation, to ensure that people have the same experiences, and thus, the same knowledge and beliefs.
That's quite so, and for some big gross things - like the influence of gravity - it appears that we may be able to achieve some constancy, by carefully regulating our experiences to achieve precisely this result. But as the world is constantly changing, and as each of us is limited to our own direct limited point of view, our capacity to achieve constancy is limited, and always subject to question from the periphery, from personal experience.
Because people have different points of view, because people have different experiences, they come to mean slightly different things by their words, to develop slightly different principles of reason, to develop slightly different pictures of reality. Multiply this over a lifetime, and over seven billion people, and you have the recipe for relativism.
Our differences in knowledge and belief - our legitimate differences in knowledge and belief - lie precisely at those fault lines where our personal experiences differ. A person borne in injustice will come to have a different view of fairness than one born in a society of equality and right. A child raised in starvation will have a different view of food than one raised in plenty. Our beliefs - even our scientific beliefs - are ineliminably subject to our personal experiences. And that's a good thing, because in this is our capacity, as individuals, and as a society, to learn.
This view should not be confused with the view that it's all a big mystery and that "anything goes."
First of all, from the fact that your knowledge differs from another's, it does not follow that you cannot criticize, or have no grounds for criticizing, another's knowledge. One appeals to one's own experiences, one's own reason, and invites the other to consider similar experiences, to follow a similar reasoning, to explore and to experiment. Because we all have different experiences, our individual experience becomes a basis on which to criticize others' points of view.
And second, this does not grant any sort of license to someone who asserts some proposition on the basis of no experience, no reasoning, whatsoever. Such a person has produced exactly the opposite of knowledge, some set of statements that will not be revised, not even in the face of contradictory experience.
The fact that we each have different experiences, and hence, different knowledge, does not free us from the constraint of basing our knowledge on experience and reasoning, whatever they may be for each of us. That each of us has a slightly different basis for knowledge or belief does not legitimize the employment fo no basis for knowledge or belief.
Relativism is the open-eyed recognition that knowledge and truth are empirically bound, and hence contingent and subject to change, not the uncritical acceptance of any proposition, no matter how poorly formed and supported.
Finally: one may ask, isn't this basis in 'experience' and 'reason' itself a common, non-relative article of knowledge? Yes, one could say such a thing - but swuch a sentence remains true only if it is not examined in any sort of detail. As we push the parameters, as we come to ask for a definition of 'knowledge', 'experience' and 'reason' we find that these concepts, and the logic that relates them, vary from person to person.
The proposition "knowledge is based in experience" itself varies slightly from person to person, and its experession in a language represents an abstraction of the actual belief, as instantiated in different people, but not the belief itself. Each person wears his or her experience differently, and part of the challenge (and the fascination) of life and interaction is to understand this.