It's Never a Bird, Until It is

 @PBSSpaceTime

  "It's never aliens until it is". 

This creates "a bridge too far", as we are never allowed to step onto the path of discovery, until we have already arrived at the destination.

There is no other domain where such prohibition of reason exists. #NonHumanCraft #UFO

This also has the effect of "zeroing out" any kind of signal of Non Human Intelligence, preventing such signal from accumulating into a meaningful proof. 

It may be that you have 10 different indicators hinting at contact, but if none of them are allowed to count for anything on their own, then the aggregate signal is still zero.

For example say you are out at sea and in the distance you think you see a bird.   

You can point to the evidence that something airborne is moving.   

But it's "NEVER" a bird until it is so  you rule out that evidence.   

Then you can point to the evidence that you hear a bird sound. 

But it's "NEVER" a bird until it is so you rule out that evidence.   

The two pieces of evidence combined may increase the weight of evidence in at worst a linear way and at best a non linear way in favor of this being a bird. Meaning the weight of the combined evidence is potentially stronger than the sum of the parts.   

But if both individual samples are set to zero, because by themselves, they were  not 100% conclusive, then there is no accumulation of evidence. 

There is no bird. Even though there clearly is.