 A different strategy for avoiding the extrapolator’s circle is to remove the black box and compare the two mechanisms but argue that they do not have to be causally similar at every stage for extrapolation to be justified. This approach avoids the circle because the suitability of a model can be established given only partial information about the target. For example, Steel argues that only the stages downstream from the point where the mechanisms in the model and target are likely to differ need to be compared, since the point where differences are likely will serve as a bottleneck through which the eventual outcome must be produced.