Knowledge vs Technology

Here’s a little thing I wrote down a couple of years back:

Question: Does the following statements represent three different stages of technological development or does two of them represent the same stage? In some sense it should boil down to how we define the word ‘technology’, or at least its relation to ‘knowledge’.

  1. We don’t know how to build a commercially feasible fusion reactor.

  2. We know how to build a commercially feasible fusion reactor, but we haven’t built one yet.

  3. He have built one commercially feasible fusion reactor.

The key is how to handle ‘know’ in the second statement. One could argue that no matter how sure we are on how to construct it (down to every detail), statement three is still superior since we have actually one functioning reactor to show. But at the same time if we would collect all the uncertainties in our models/​simulations/​calculations etc in a variable u. What happens as u->0 ? Shouldn’t the gap between 2 and 3 go to zero? That would mean that enough knowledge about a technology is equivalent to actually possessing the technology.

EDIT: The utility of having a reactor is of course higher than knowing how to construct one, so if we measure technological level as a function of the utility gained from that technology then the resolution is trivial.