I very much understand the difference between evidence and proof, without you having to be condescending. And a court of law can ONLY ever determine the best explanation for the evidence of a past set of events. The court of law was not AT the event. It is only told a explanations from two perspectives, and must decide which best fits the facts, within the bounds of the legal system. I don't care how you define "burden of proof" - I know what it is:

: There is a reason why a court has to prove you are guilty instead of you
: having to prove that you are not guilty.

Our court system has decided a priori to consider all defendants innocent until proven guilty. THAT is the basis on which the burden of proof is founded. That is the framework in which the court system works. That is why prosecution must prove the defendant guilty. That is exactly the process I am attempting to explain.

: I have explained this to you before but you are obviously not getting it.

No, you are are choosing to find ways to explain something that I am already saying, attempting to make me out to be the fool for "not understanding".

: Your vital spark is not well defined and you have given no reason to believe
: it exists - you have given no mechanism that explains how it operates or
: the limits of what it can or can not do.

Your insistence that there is no 'vital spark' to life is not well defined and you have given me no reason to believe it does not exist - you have given no example of an observable or repeatable demonstration of life arising from non-life.

: So we can ignore your vital spark idea until you do the work.

Ok, that's your choice. At this point, it's entirely irrelevant because no one has observed the requirements to refute the theory, and no one has observed all of life to spot a single life arising from non-life. And so, Science continues. Yay science!

: Demonstrate that it exists.

Evidence: every life you see see born or cloned from existing life. This is not proof. It is a demonstration that supports the premise of this 'vital spark'.

: Show us how it works.

You see how it works, every time a life is born or cloned from existing life.

: Show us how you know that it exists and how it operates.

See: above.

: Explain why we even need the concept.

Why? Need of a concept doesn't dictate its truth or not. Neither has the evidence I've provided prove that the 'vital spark' exists. The observations only support the theory that it exists.

: What does it do that chemistry doesn't do?

What does what do? Life arises from life. Scientists use the laws of chemistry to explain the process of how and why this happens. Scientists have not (yet?) been able to recreate this process without using existing life.

: It is not up to me to disprove leprechauns

Well it would be to someone who already firmly believes in leprechauns.

: and I don't have to concede that they exist just because someone tells me that
: he believes in them.

No one said you had to concede that they exist.

: You can't say that it is up to me to disprove leprechauns.

To the person who believes in them, it is up to you to prove it to them, to change their minds.
Otherwise, what do you care?

I'm not telling you "the vital spark exists, damnit!"
I'm telling you "you are free to believe it doesn't, and continue your life and scientific exploration of the universe under that presumption if you wish; likewise, my belief that it does exist is perfectly viable as well, and neither of us have any scientific proof to refute the other's position"

Look, you and I are obviously not seeing eye to eye on this concept of evidence vs proof. Either I'm not explaining myself enough, or you're not getting what I'm saying. Or vice versa. Or, maybe we as a matter of fact agree, but our words are not in synch. Whatever the case, please do not resort to any ad hominim attack implying I'm some kind of fool or unintelligent because I "don't understand" some simple logic.
I'm fine ending this conversation now (and I want it to end), in an effort to stop spamming HBO with this circular debate that has nothing any more to do with Halo.