Vast question, but I'd say that in most cases it boils down to determining whether a statement is subjective or objective. Example:
My * is big - subjective statement, opinion
My * is bigger than yours - objective statement, fact
I might use a measuring tape.
Trust me, you'd realize you wouldn't need a measuring tape as soon as you see it. I built this cell phone myself, and it's both heavier and larger than my old desktop.
Nothing in the universe is always true to us mortals. Facts are provisionally true given
Gravitational pull of your planet
Facts are conveniently wrapped in envelopes of the environment they sit in at that moment.
If I said it, it's a fact. If anyone else said it, it's not.
Just kidding. If a statement is subjective, then it is an opinion. Example: I like hamgurgers. If a statement is objective and is true, it is a fact. Example: The earth goes around the sun.
This is an easy one, for there is only 1 method that humans have ever had available to them.
The measurement that you should use is: "The Scientific Method".
Theres plenty about it on the internet :)
Read Stephen Hawking's new book, "The Grand Design". It's not postmodern waffle, it's not even a postmodern pancake. It's post-classical waffle . . . also known as quantum theory. Your "classical" view of the universe is passe . . . so yesterday. It's a quantum world now, baby!
Okay, okay . . . what the heck, here's the relative passage from The Grand Design . . .
. . . common sense is based upon everyday experience, not upon the universe as it is revealed through the marvels of technologies such as those that allow us to gaze deep into the atom or back to the early universe.
Until the advent of modern physics it was generally thought that all knowledge of the world could be obtained through direct observation, that things are what they seem, as perceived through our senses. But the spectacular success of modern physics, which is based upon concepts such as Feynman’s that clash with everyday experience, has shown that that is not the case. The naive view of reality therefore is not compatible with modern physics. To deal with such paradoxes we shall adopt an approach that we call model-dependent realism. It is based on the idea that our brains interpret the input from our sensory organs by making a model of the world. When such a model is successful at explaining events, we tend to attribute to it, and to the elements and concepts that constitute it, the quality of reality or absolute truth. But there may be different ways in which one could model the same physical situation, with each employing different fundamental elements and concepts. If two such physical theories or models accurately predict the same events, one cannot be said to be more real than the other; rather, we are free to use whichever model is most convenient.
In the history of science we have discovered a sequence of better and better theories or models, from Plato to the classical theory of Newton to modern quantum theories. It is natural to ask: Will this sequence eventually reach an end point, an ultimate theory of the universe, that will include all forces and predict every observation we can make, or will we continue forever finding better theories, but never one that cannot be improved upon? We do not yet have a definitive answer to this question, but we now have a candidate for the ultimate theory of everything, if indeed one exists, called M-theory. M-theory is the only model that has all the properties we think the final theory ought to have.
Oops, forgot to include this passage as well . . .
. . . Though realism may be a tempting viewpoint, as we’ll see later, what we know about modern physics makes it a difficult one to defend. For example, according to the principles of quantum physics, which is an accurate description of nature, a particle has neither a definite position nor a definite velocity unless and until those quantities are measured by an observer. It is therefore not correct to say that a measurement gives a certain result because the quantity being measured had that value at the time of the measurement. In fact, in some cases individual objects don’t even have an independent existence but rather exist only as part of an ensemble of many. And if a theory called the holographic principle proves correct, we and our four-dimensional world may be shadows on the boundary of a larger, five-dimensional space-time. In that case, our status in the universe is analogous to that of the goldfish.
For more info on the holographic principle, check out this wiki.
Let me know when you find it, Derry.
There's reality and then there's our perception of it. At a very basic level, everything we perceive and think is subjective.
So what do we uphold?
Whatever you feel strongly enough about.
I believe in freedom and free will. They are what I uphold.