Perhaps the most succinct statement of the Enlightenment attitude toward the philosophical tradition is expressed by Immanuel Kant in the Preface to the Second Edition of his Critique of Pure Reason (from Cambridge Edition of the CPR):
Whether or not the treatment of the cognitions belonging to the concern of reason travels the secure course of a science is something which can soon be judged by its success. If after many preliminaries and preparations are made, a science gets stuck as soon as it approaches its end, or if in order to reach this end it must often go back and set out on a new path; or likewise if if proves impossible for the different co-workers to achieve unanimity as to the way in which they should pursue their common aim; then we may be sure that such a study is merely groping about, that it is still far from having entered upon the secure course of a science; and it is already a service to reason if we can possibly find that path for it, even if we have to give up as futile much of what was included in the end previously formed without deliberation.
Kant's paragraph simultaneously reveals what the Enlightenment sees as the problem with classical philosophy, and provides the Enlightenment solution to it. The problem (as the Enlightenment sees it), is this: Philosophy, as traditionally practiced, is futile. Rather than continue along the traditional lines, Enlightenment philosophers prefer to jettison the philosophical tradition altogether and make a fresh start, a start that promises to support the new science then emerging and perhaps make progress in its own right. But how does one reasonably dismiss the philosophical tradition as futile? Something is futile if it fails to do what it proposes to do. It seems like the Enlightenment philosopher must therefore be a master of the philosophical tradition, at least enough to understand what it proposes to do and to show that it fails to achieve it, and will continue to fail.
Understanding the philosophical tradition, however, is a task for a lifetime, and it is just this task that the Enlightenment philosopher is desperate to avoid; at all costs he must avoid engaging the classical philosopher in a never-ending roundabout concerning the meaning and "end" of classical philosophy. What the Enlightenment philosopher requires is a means to summarily dismiss the philosophical tradition, a means that relieves him of the task of engaging the classical philosopher on the latter's preferred ground and allows him to get on with the modern project of reconstructing philosophy.
In the Preface, Kant both proposes such a means and applies it. He writes that a "treatment" can "soon be judged by its success." We immediately hit a snag. Mustn't we understand the philosophical tradition so that we can know what "success" means with respect to it? We are right back to engaging the classical philosopher in his favorite game of never-ending debate. Kant first deals with this problem rhetorically, by hurrying the reader past it with that "soon." He then sidesteps it by proposing, or rather asserting, several measures by which a project of thought may judged. First, does it "get stuck" when it approaches its end (i.e. goal)? Second, does it repeatedly start over again in frustration? Third, does it result in unanimity of opinion as to its conduct? Kant applies his criteria to logic, mathematics and the new science of physics in turn, not surprisingly concluding that they all pass the test. He then turns to metaphysics (i.e. classical philosophy):
Metaphysics - a wholly isolated speculative cognition of reason that elevates itself entirely above all instructions from experience, and that through mere concepts (not, like mathematics, through the application of concepts to intuition), where reason thus is supposed to be its own pupil - has up to now not been so favored by fate as to have been able to enter upon the secure course of a science, even thought it is older than all other sciences, and would remain even if all the others were swallowed up by an all-consuming barbarism. For in it reason continuously gets stuck, even when it claims a priori insight (as it pretends) into those laws confirmed by the commonest experience. In metaphysics we have to retrace our path countless times, because we find that it does not lead where we want it to go, and it is so far from reaching unanimity in the assertions of its adherents that it is rather a battlefield, and indeed one that appears to be especially determined for testing one's powers in mock combat; on this battlefield no combatant has ever gained the least bit of ground, nor has any been able to base any lasting possession on his victory. Hence there is no doubt that up to now the procedure of metaphysics has been a mere groping, and what is the worst, a groping among mere concepts. (again from the Cambridge Edition of the CPR).
Metaphysics, according to Kant, fails all his tests for a successful "treatment of cognitions." It repeatedly "gets stuck", it must repeatedly start over, and their is no unanimity of opinion in its adherents. The question of the "success" of classical philosophy still lurks in the background, since a philosophy "gets stuck" to the extent that it no longer makes progress toward its end (goal); but it would seem one must know the end of something to know if progress is being made towards it, so Kant's conviction of metaphysics on the charge of "getting stuck" implies that Kant knows the end of classical philosophy. As noted, however, Kant wants to avoid the question of the end of philosophy at all costs, as it will (he thinks) lead him into the interminable debates of the philosophical tradition. He cleverly brackets the question of the end of philosophy by saying that metaphysics "does not lead where we want it to go", changing the objective question of the end of philosophy to the subjective question of whether it gives us what we want; and in Kant's case, it manifestly doesn't. And this is the bold stroke of the Enlightenment that allows it to summarily dismiss the classical philosophical tradition: It is the philosopher himself, and his subjective desires, that is the measure of philosophy.
We can sympathize with the motivation of the Enlightenment philosophers. The world seemed to be undergoing revolutionary change; from the discovery of new continents, to the staggering innovation that was the birth of modern science, to new, republican political ideas, everything was becoming new; and the philosophical tradition appeared (I emphasize appeared) to be inadequate to deal with it. What was needed was a revolutionary new philosophy to accompany the revolutionary new world in the making. Slogging through the finer points of the Five Ways or Plotinus to eventually disprove them would miss the point entirely. Columbus didn't spend a lifetime justifying his voyages to skeptics; he never would have gotten out of port if he had wasted time on the timid. Nor did Galileo or Newton puzzle themselves over whether their new physics could fit within Aristotelian metaphysics. Like Columbus, they simply and boldly went ahead with their investigations and discovered what would never have been discovered any other way. Aristotle must reconcile himself to the new physics, not the other way around. Similarly, the Enlightenment philosopher cannot bear to be bound within the philosophical tradition as in a cage. Like Columbus and Newton, he must leave the past behind and strike out for fresh lands.
But there is a key difference between Columbus and Newton on the one hand, and a philosopher on the other. In a certain sense it doesn't really matter if Columbus or Newton knew what they were doing; Columbus always thought he actually made it to the East Indies, and Newton spent much of his time in bizarre religious speculation. But you can still discover the Caribbean even if you're navigation is so poor that you think you've arrived in Indonesia. The philosopher, however, is the wise man, and the wise man, as opposed to the fool, knows what he is doing. Philosophy, perhaps, may even be defined as striving to know what you are doing. So the philosopher must be self-aware in what he is doing, and this holds true for the Enlightenment philosopher as much as the classical. Kant can't simply assert that he doesn't like classical philosophy and he's going to try something new; he's got to give a reason for dismissing classical philosophy.
As I've hope I've showed above, the reasons Kant gives for dismissing the philosophical tradition are a bit of a bluff. He says that philosophy has proven itself futile, but he never actually proves the point; he asserts that it has and hopes the reader goes along. He must bluff because the attempt to prove the point would lead him into the interminable arguments so beloved of the classical philosopher, and this is just what he wishes to avoid.
And this is what Richard Dawkins doesn't seem to understand. Similar to the typical Enlightenment philosopher, he doesn't really have time for classical philosophy, which he sees as a waste of time. He should, then, summarily dismiss it in the fashion of Kant. Not having the self-understanding of a true philosopher like Kant, however, he instead takes a halfway position that is unreasonable on any account. He gives a little time to classical philosophy, enough to rapidly refute classical arguments for God, he thinks. But all his simple refutations reveal is his simplistic and superficial understanding of the arguments involved. This doesn't bother him, however, because he has already decided on Enlightenment grounds (i.e. the manifest futility of classical philosophy) that the arguments are worthless. Rather than an insult, I suspect he sees his condescending to treat the classical arguments even in a superficial manner as generous, since from his perspective they rate no treatment at all.
Efforts like those of Richard Dawkins discredit the Enlightenment tradition (if we can call a "tradition" something that was born in the rejection of tradition). Kant dismissed classical metaphysics as a mere "groping" among concepts, but at least the classical philosophers knew what it meant to grope. Even more embarrassing is a contemporary thinker, supposedly freed two hundred years ago by Kant from even needing to address classical philosophy, blundering about in classical philosophical concepts in a manner that it would be too kind to call "groping."