If this were a class in logic, the meaningless symbols "lefty" and "righty" would be replaced by "true" and "false".

But we can't do this. Yet. We have to show how to go from the meaningless symbols "lefty" and "righty" to the meaningful symbols "T" and "F". The lambda calculus shows us how. The lambda calculus describes a universal computing device using an alphabet of meaningless symbols and a set of symbols that describe behaviors. And this is just what we need, because we live in a universe where atoms do things. "T" and "F" need to be symbols that stand for behaviors.

We look at these symbols, we recognize that they are distinct, and we see how to combine them in ways that make sense to our intuitions. But we don't know we do it. And that's because we're "outside" these systems of symbols looking in.

Put yourself inside the system and ask, "what behaviors are needed to produce these results?" For this particular logic operation, the behavior is "if the other symbol is me, output T, otherwise output F". So you need a behavior where a symbol can positively recognize itself and negatively recognize the other symbol. Note that the behavior of T is symmetric with F. "T positively recognizes T and negatively recognizes F. F positively recognizes F and negatively recognizes T." You could swap T and F in the output column if desired. But once this arbitrary choice is made, it fixes the behavior of the other 15 logic combinations.

In addition, the lambda calculus defines true and false as behaviors.¹ It just does it at a higher level of abstraction which obscures the lower level.

In any case, nature gives us this behavior of recognition with electric charge. And with this ability to distinguish between two distinct things, we can construct systems that can reason.