Logosphere should definitely be a word

The earlier thread about onions led me to think about expressions in English that use a unquestioned known truth to express the truth in another statement. There are a number of these, but one used in the midwest part of the US is the title of this thread. It is used when an individual says something is true -- and compares it to a 'natural truth'. One which is less than PC today is 'is the Pope Polish?'.
Are there other examples from the English speaking world of these types of expressions?

That the current pope is Polish is a contingent truth rather than a "natural truth".
That triangles have three sides is not a contingent truth and the rhetorical question
'Does a triangle have three sides?' does the job you're referring to.

Whereas, 'Is the Pope a Catholic', which is used quite a lot in the UK could be said to be a natural truth since to be other than a Catholic in that position denies the office.

The three most common in my logosphere (I don't know if such a word exists, but it should) are "does a bear s* in the woods?" "is the Pope Catholic?" and "is a frog's a** waterproof?" Reluctant as I am to repeat cliches, I usually rearrange them into "does the pope s* in the woods? Is a bear Catholic?" etc. Since the frog's anal integrity is less commonly repeated, I leave that intact.

Not only do I like 'logosphere', but I've never heard the 'frog' cliche, and while it may be a tad uncouth, I must say I like it.