Definitely, and that is exactly the case in weak gravitational lensing, where the effect is small enough to not significantly distort the image. Also, this is exactly how this effect was first measured by Eddington!

Usually, what would happen is that we first know there is a massive object in the way to a far away galaxy or cluster, and then by doing some (mostly statistical) analysis, would learn about the details of the massive object through its effect on the observed galaxy.

The wiki page has some nice explanations.

The idea is that you don’t have any innate knowledge that comes from sensory experience or manipulation on that experience.

In fact, Hume argues that the entire concept of self is a sensory illusion in a way.