Since atoms are mostly "empty space,"

[DetlefK]

28. Sorry, but atoms are not "mostly empty".

When encountering such tiny scales, you have to give up notions of absolutism. "Empty", "full", "here", "there" only work in classic newtonian-galileic physics.

There is the wave-particle-dualism, but in an atom electrons are best described by a wave-function. And according to Born's interpretation of the wave-function, the square of the absolute value of the wave-function is equal to the probability-density of the particle. (This equality no longer holds when the particle becomes relativistic. Works with Schroedinger-equation, but not with Dirac- and Klein-Gordon-equation.)

A spatial probability-density means, that the particle is never in one particular place, but is smeared out over several places. He is maybe "here" and maybe "there", as long as nobody is looking. Once someone "looks", the wave-function "collapses" from a multitude of possible states into one state: That one state reaches 100% probability, the rest drops to 0%.

So, in recap: Atoms are neither empty nor full. They are filled with maybes.



And concerning your question: Solidity is not subjective, you can't talk it away or ignore it at will. It's an emanation of a balance between attracting and repulsing forces that keep atoms in their place.
And the Pauli-exclusion-principle says: "The atoms of your finger-tip shalt not be in the same place as the atoms of your desk." (Well, the electrons and nucleons of the atoms, but the effect is the same.)