>In constructor theory, physical laws are formulated only in terms of which tasks are possible (with arbitrarily high accuracy, reliability, and repeatability), and which are impossible, and why – as opposed to what happens, and what does not happen, given dynamical laws and initial conditions. A task is impossible if there is a law of physics that forbids it. Otherwise, it is possible – which means that a constructor for that task – an object that causes the task to occur and retains the ability to cause it again – can be approximated arbitrarily well in reality.

This seems to be false, as there is no physical law preventing entropy from decreasing but there is a physical law which prevents the existence of a 'constructor' capable of decreasing entropy.

>Moreover, it is a fundamental idea of constructor theory that any transformation that is not forbidden by the laws of physics can be achieved given the requisite knowledge. There is no third possibility: either the laws of physics forbid it, or it is achievable.

Either they are saying something is achievable if and only if there is a constructor for it, which is false (see previous point), or they are claiming something is achievable if and only if the laws of physics don't forbid it, which makes this 'fundamental idea' vacuous.