When we keep hoping and praying for something that defies logic we delude ourselves into believing.

From Cher:

What am I supposed to do?
Sit around and wait for you?
And I can't do that
There's no turning back
I need time to move on
Cause I've had time to think it through
And maybe I'm too good for you

From Survivor:

Hope still burns eternal
We're the keeper of the flame.

An interesting question.

In the story of Pandora (if you don't know the story, look it up), often it is misunderstood that 'hope" was considered by the ancient Greeks to be yet another plague for men to suffer, because most people tend to hope for things that will never come true and are thus faced with one crushing disappointment after another.

I tend to be guided by words from the "Serenity Prayer", only I leave the first word "God" out, making it in my mind the "Serenity Mantra" which would read, "Grant me the serenity to accept the things I cannot change, the courage to change the things I can, and he wisdom to know the difference." There is a lot of wisdom in those words.

As life instructions it would be...

1. Determine how much or hoe little, or if at all, your actions will influence a desired outcome.
2. If your actions can have an influence, will the amount of effort be worth the reward?
3. If so, take action to achieve your desired outcome. If not accept things as they are.
4. Before taking action, do some research to make sure your original assessment was accurate.

When it comes to "hope" I first determine how much power I have to change or achieve the desired outcome, and if things are not in my control and/or I have no influence, I just accept things as they are. I think hoping for things that are out of your ability to influence the outcome is where you step over the line into delusion.

Psychiatry: A false belief or perception that is a manifestation of a mental illness: delusions of persecution. Example, delusion of grandeur.

Hope becomes a delusion when it involves the obvious denial of proven facts as we understand them to be at this moment in time. If I have hope for a young but chronic drug addict that has let everyone that loves him down over and over again, it is not delusional if there remains a chance that this time the circumstances will be right to support and engage him for treatment. Never lose hope in the neuroplasticity of the human brain.

It seems to me that hope and delusion can be the same thing or two very different things, If you do something to hedge your bets and hope it work that is far different, than doing the same thing over and over again and hope for a different result that is not only a delusion but, is insane.