  Conventional quantum mechanics describes a pre- and post-selected system in
terms of virtual (Feynman) paths via which the final state can be reached. In
the absence of probabilities, a weak measurement (WM) determines the
probability amplitudes for the paths involved. The weak values (VW) can be
identified with these amplitudes, or their linear combinations. This allows us
to explain the "unusual" properties of the VW, and avoid the "paradoxes" often
associated with the WM.
