It seems like it might be reasonable to take this story with a grain of salt - it could be a tall tale, no matter how entertaining it seems. I'd be interested to know if anyone has any better sources on this!
I remember hearing a talk by Dana Scott where he said that indeed this is a tall tale, and that Church chose the λ just because...he needed a letter. (Maybe somebody knows where to find this talk online?)
According to Dana Scott at least the goofy 'hat calculus' story I posted before is a myth: https://twitter.com/danghica/status/1124567463306440704… - tl;dw: somebody actually wrote to Alonzo Church asking why he used ‘λ’ and he replied back “Eeny, meeny, miny, moe…”
A further twist in this tale is that Church _did_ actually come up with the 'Hat Calculus', but it was actually just a precursor to the lambda calculus: http://akivaleffert.com/papers/hat-calculus.pdf…
A further twist in this tale is that Church _did_ actually come up with the 'Hat Calculus', but it was actually just a precursor to the lambda calculus: http://akivaleffert.com/papers/hat-calculus.pdf…