Why must only one deity be real-enough to effect higher yields? If there was an increase in yield after sacrifices to any 'supernatural' entity, why would this not support them all? If there is an increase in yield after sacrificing to Mubu and after sacrificing to Yubeem, but not when sacrifices are made to others, is this 'fairly decent supportive verifying evidence' for Mubu and Yubeem? What if it is three deities? Four? How many deities must be 'confirmed' before we have 'too many' to serve as 'supportive verifying evidence'?
You are missing out on a few important concepts.
#1) Plausible mechanism.
If you want to imply that goat sacrifice causes better harvest, you need to at least postulate a mechanism. In this case, it's "magic" - which unfortunately for you is the same thing as saying "make believe".
No one claims that gravity is caused by magic or that magnets are caused by magic. "Magic" is the answer people give when they are too lazy to bother doing the work.
#2) Plausible causal agent.
If you want to imply that goat sacrifice causes better harvest through "magic" from Mubu, you need to explain why murdering a goat would have this sort of outcome. Why does the non-corporeal, all powerful, eternal Mubu require the murder of a lowly goat in order to make plants grow?
#3) Control group
You don't test the plausibility of a "magical" event by performing a slightly different "magical" event and seeing if you get similar results.
You test the plausibility of a magical event by NOT performing it and seeing if you get the same results.
You need two fields next to each other and growing the same crops. Sacrifice a goat for one field and leave the other one alone. THEN evaluate the effect.
#4) Quantifying the results.
"Increase in yield" is not a specific definition upon which to assume the presence of and interaction with a "magical" being.
If the difference in yield from one field to the next is 5% or less, that can be adequately explained by noise in computation, differences in soil, drainage, shade, wind direction, harvesting technique, harvesting time, etc etc etc.
In order to demonstrate magical agency the difference in yield between the two fields needs to be UNQUESTIONABLY substantial.
For example: If you murder a goat in this field, it yields 500% MORE crops than in the field right next door.
#5) Demonstrable change in production
Not just an increased yield. If we are talking about an all powerful deity using magical powers, we want to see that mechanism demonstrated in ways which can not be explained through normal growth processes.
If you plant field A and B on the same day, then sacrifice a goat in field A, field A should be ready to harvest 15 minutes later. The plants should magically burst from the ground and ripen at a rate unseen and unexplainable through any means apart from magic.
Having plants grow at the same pace as the control field is insufficient to demonstrate supernatural agency.
™ Version 4.2
