Is a Privacy Invasion Still Wrong If the Person Never Knows?

Suppose someone reads a friend's diary while the friend is away, returns it, never uses what they learn, and is never discovered. If harm means only distress that a person experiences, the act seems to have no victim: the friend feels no anxiety and nothing visible changes in their life.

Philosophical accounts of privacy, however, do not treat it merely as protection from bad consequences. Privacy also concerns a person's control over who may know what about them. By acquiring the information, the reader has already bypassed the diary owner's decision. That control has been taken away in practice even if the secret never travels any further.

We should therefore distinguish felt harm from being wronged. The first must enter someone's experience; the second can occur without their knowledge, just as an undiscovered deception still changes the character of a relationship. My judgement is that ignorance does not erase the wrong, although it affects the severity of its consequences. Accidentally seeing a line and closing the diary differs from deliberately reading every page; using the information to manipulate someone adds further harm. The point is not to invent a mysterious loss. It is to recognise that respecting another person means allowing their boundaries to operate, not merely avoiding upsetting them.

https://plato.stanford.edu/entries/privacy/
https://plato.stanford.edu/entries/respect/