What our having a reason means.

 Why are we , human beings special, unique, different from other animals?

Because we are thinking, and can choose something to do by ourselves.

We have a reason.it means we are rational creature.

Other animals can't choose what they think but just follow the nature or habit. 

The human beings need and want noble and spiritual purpose.

We seek to the truth, which is absolute. 

Sometime we know that the right and truth is subjective and relative . 

But at that same time, we have a concept that there is a truth even though we dont know yet exactly what it really is. 

Anyway we can have a confidence that there is a certain purpose more important than eating , sleeping, marrying and so on 

The fact that there is a purpose, need, want referes to a background about ourselves.

That is we are designed to pursue the truth .

The proposition that we are designed means there exists a designer who design all of us very carefully.

And it also means if we ,human beings follow the original purpose of our designer , we can be truly happy.

Because we seek to way to be truly happy that is our innate purpose.

So we have to find the designer who know how to live well on purpose.