I've been thinking... How is it that we can meaningfully even think about full semantics second order logic of physics is computable?

What I mean is... if we think we're talking about or thinking about full semantics? That is, if no explicit rule following computable thingy can encode rules/etc that pin down full semantics uniquely, what are our brains doing when we think we mean something when we mean "every" subset?

I'm worried that it might be one of those things that feels/seems meaningful, but isn't. That our brains cannot explicitly "pin down" that model. So... what are we actually thinking we're thinking about when we're thinking we're thinking about full semantics/"every possible subset"?

(Does what I'm asking make sense to anyone? And if so... any answers?)