Some thoughts about postmodernism and truth

I've been talking to Ben and Jian Han alot recently about truth and reality in general.

How do we know that something is true?
Isn't everything based only on our perceptions of it?

These were the core questions we were throwing around the discussion table. For it seems that a statement like 'that chair is red' might be true for me, but might not be for you. Red is after all, experienced.
So how do we know if we're both experiencing the same thing?

Let me dig into this:

What is 'red'?
I guess we science students can start by asking the question 'What is red?' or how we even get to see things in the first place.

A simple way to describe the mechanism surrounding the process of a person seeing a red chair is this; light gets reflected off the chair that corresponds to a certain wavelength of light that corresponds to what our brains process to be what we experience as 'redness' (this though, will probably open up the can of worms called 'consciousness and dualism').

From the above process though, I don't think it's too big a leap to make to assume that something is red, even if a color blind sees it as grey because red in this case, is an objective description of a wavelength of a certain quantity.



Which Ben replies to by asking "But even the measurements of wavelengths are subjective to some extent, are they not?"

I guess this then boils down to how accurate our five senses are and how reliable they are in determining reality (five sense being touch, sight, smell, sound and taste).

This then possibly might go back all the way to Descartes demon and deeper into the realm of philosophy which I dare not tread for now...

But if the worry is postmodernism (which I think it is) then I guess more can be said about this later on...