There are over 7 billion people in the world, and with each person on the planet comes a unique perspective on the nature of things.
People are born into different families, different countries and different cultures, all of which shape the way each of us perceive the world.
We are also different from each other in many other ways. Male and female; fair-skinned and black; straight, gay, transgender; disabled, blind, colour-blind. So many things combine to make us very different from each other.
When it comes to thinking about each other’s beliefs and opinions, these too are many and varied. What we think about the nature of the world, reality, purpose of life, meaning of things, morality, religion, and God even, our beliefs are not necessarily going to be the same as what other people think. When we consider the multitude of influences that go into making us who we are, it is easy to see why this is the case.
So with this in mind our starting-point for evaluating another person’s beliefs and opinions must surely be that of asking questions. For example:
- Why do they believe that?
- When did they acquire these beliefs?
- What has led them to continue having these beliefs?
- How are my beliefs different to theirs?
- Where might we agree on this issue?
And so on…
Of course, if we all have our own unique beliefs and opinions then how do we decide which of them are reliable or true, if any?
In his book “The Problem of Philosophy”, the Philosopher Bertrand Russell illustrated this point in the following manner:
“To make our difficulties plain, let us concentrate attention on the table. To the eye it is oblong, brown and shiny, to the touch it is smooth and cool and hard; when I tap it, it gives out a wooden sound… but as soon as we try to be more precise our troubles begin. Although I believe that the table is 'really' of the same colour all over, the parts that reflect the light look much brighter than the other parts, and some parts look white because of reflected light. I know that, if I move, the parts that reflect the light will be different, so that the apparent distribution of colours on the table will change. It follows that if several people are looking at the table at the same moment, no two of them will see exactly the same distribution of colours, because no two can see it from exactly the same point of view… The same thing applies to texture… and shape.” 
So if people are having different experiences of the table at the same time, whose experience is the most valid or true?
Let’s illustrate this point another way using a well-known Indian parable:
In a village three blind men were touching an elephant. They were asked to describe what they were feeling. The first blind man, holding the elephant's leg, said he was touching the trunk a great tree. The second blind man, holding the elephant's tail said he was holding a rope. The third blind man, touching the elephant’s side, said he was standing in front of a great wall. Each blind man was convinced he was right and others were wrong, even though they were all touching the same elephant.
The table and elephant analogies suggest there is no such thing as Absolute Truth; that in fact all truth is relative to the individual and many philosophers will accept that this when it comes to social, moral and religious truth-claims. However, this is not to say we are now living in a world devoid of any truth or sense of certainty.
For instance, we can’t drive up to a gas station and decide to fill up our vehicle’s fuel tank with milk. Everyone at the gas station would agree that in order to make their vehicle work they need to put gas, or petrol in it. A combustion engine will not run on milk. Even if someone insists it does, they will soon come to realise they are wrong, especially when they attempt to start their car and drive off. So although someone next to me may have been born in a different country, have a different skin colour, is the opposite gender to me, and different in all manner of other ways, both of us would agree that we need to put gas into our vehicle in order to continue driving it.
One final point. Sometimes a disagreement between two people is simply about the meaning of the words we use. For instance, consider the person who believes the earth is flat versus the one who believe it is not. Both would say that the earth is “Round”, but both would also clearly mean different things by this.
 Taken from chapter 1, “Appearance and Reality”.