The technical community has so far defined network neutrality in terms of specific mechanisms, e.g., policing or shaping. We argue that these definitions are problematic: according to them, a non-neutral network may be preferable (for all users) to a neutral one; moreover, these mechanisms can have the same effect on the target traffic as legitimate ISP practices like traffic engineering or peering agreements. We argue that we should not try to define or enforce network neutrality through technical means at all. Instead, the network layer should provide transparency, i.e., low-level loss and delay information that is admissible in court and can be used as a building block by regulators to reason about ISP neutrality at a higher level. We close by outlining challenges and possible solutions.