You need two because without the other everything would be the same which would be impractical when trying to discuss something or like someone said earlier giving directions.
can you call something false if you do not know truth?
Yes, because calling something something doesn't make that something something. Oh so bad sentence structure...
but why is there always two? up/down, forward/backward, left/right, beginning/end
Because opposite concepts are easily noticed, or at least more easily noticed than concepts that lie close to each other in meaning.
can there be darkness without the presence of light?
Yes, but if you do not know of light, then there is no darkness to define. It would just be, and you would not need a word to mark it as different from light.
i'll ask my question again: why is there always two? up/down, forward/backward, left/right, beginning/end
Well, in your examples alone you seem to forget sideways and middle a whole lot. See, you only notice the different extremes, while you ignore the existence of the concepts in between. It's not that there are only two. It is that no one cares about what's in between. Life isn't black and white, it's a cacophony of grays.
I'll focus on one of the questions, since they're all essentially the same.
So left and right. Let's say I just don't know about right? I can still go left all I want. Or you could know about right, but you just don't know the name for it. But still, you don't have to know about something for it to exist. You can experience happiness without having experienced sorry, but it may not be as strong.
Not three cose theres only one diffrent then the other like left and right there cant be left right back or left right back front it dont make any sense its just like saying turn left..or turn right
