[IanCal]

> There's an underlying assumption that we know what walking or a taxi are. We don't.

Of course we do! The idea that every task involves some groundbreaking research into an entirely novel field is ridiculous. We often know a great deal about what it is we're about to do. Yesterday I needed to fix some chef recipes to get some monitoring working on a different OS, I could give a fairly decent estimate about how long that would take and it had some uncertainty in it. I built a simple site with stripe integration and had a good idea about how long it would take. I know more about doing that next time, too and have a better idea about how long it will take.

> We may be able to apply past experience inventing similar things to our estimations, but there is always some amount of uncertainty.

Having uncertainty in an estimate does not make the estimate pointless. Even having a lower bound can be enough. If I know a feature will not be done in under a week (because similar ones take two weeks, and this has a few extra complexities so my base assumption should be "longer than two weeks") then that might be enough for someone to not choose to implement it. I've had that before on projects, where I've given a minimum time and the feature has been dropped.

> If I don't know what a car is, asking me how long it will take to invent one so that you could use it to get to the train is inviting trouble.

But if someone said "Invent a car for me, I need to get to the station tomorrow" you could easily say that it's not going to happen within a day, and that information would still be useful.