My chief concern is that I am a bear of very little brain, and if you change the meaning of #isNil to anything at all other than "is the receiver identical to nil" you WILL (not may) confuse me.

I can understand your probably well-justified concern that power can always be misused. I also understand a key principle of Smalltalk to be ���empower and trust the programmer���. Edge cases like this where Smalltalk principles like pervasive message passing are not true bring their own share of confusion.

"How should a proxy (https://en.wikipedia.org/wiki/Proxy_pattern) to nil respond to the #���isNil��� message?"

It SHOULD NOT LIE. A proxy isn't nil, and it doesn't behave like nil, even if it is a proxy for nil. A proxy, qua proxy, can do things that nil cannot. Use another selector, #isEffectivelyNil, or whatever reveals your intentions, and give it what semantics you find useful.

I find the concept of ���is��� and ���equal��� to be generally confusing in Smalltalk. Does `#=` mean ���all state is the same���? ���all relevant state is the same (minus e.g. caching)���? ���This represents the same domain object���?

I can see how a proxy claiming to be nil is a ���lie��� for one/some definitions of ���is���, but I don���t think it���s universally true.

Really interesting conversation!