After the labyrinthine intricacies of the Mathematical mode, Kant's discussion of the dynamical sublime comes as something of a relief, in so far as it contains one of the clearest progressions of argument in any one section of the third Critique. First Kant defines 'might' as that which is superior to great hindrances, and which is to be regarded as having 'dominion' if those hindrances are themselves mighty. This definition leads, in turn, to the claim that, if we judge aesthetically that nature is might that has no dominion over us, then we are experiencing the dynamically sublime. The basis of such judgements is as follows.
If we are to estimate nature as dynamically sublime, it must be represented as a source of fear (though the converse, that every object that is a source of fear is, in our aesthetic judgement, sublime, does not hold). For in forming an aesthetic estimate (no concept being present) the superiority to hindrances can only be estimated according to the greatness of the resistance. Now that which we strive to resist is an evil, and, if we do not find our powers commensurate to the task, an object of fear. 1
Kant's point here is that to judge an object as possessing might is simply to make a logical judgement on the basis of concepts. However, if our judgement is to be aesthetic (i.e. one whose determining ground is subjective) then our estimation of the object as mighty must be determined by our affective response to it, that is by the amount of fear it would engender in our futile efforts to resist its might. 2