David Hume, like Berkeley, comes to sceptical conclusions about Cartesian ontology, after reading Bayle and Locke. Not only does he deny the ontological dualism, but he also explicitly denies the all-inclusive ontological type-distinctions between substance and modification. Foucher argues that Cartesians do not know the essence of mind and matter as they claim to; Malebranche argues that we have an idea of the essence of matter but not of mind; Locke argues that we cannot know the essence of either mind or matter; and Berkeley argues that we have a notion of the essence of mind but not of matter. Hume concludes that we have no idea, and thus no knowledge of any substance at all. [...]

Hume argues that impressions and ideas are the only objects that do exist. When we examine our idea of substance, for example, we find that it is not an idea of an independently existing entity at all, but only a compound idea of a collection of related perceptions. [...]

Hume can be seen as making sense of the Cartesian way of ideas by retaining the epistemological likeness principle, but he does so only by abandoning the dualistic system that gives rise to difficulties. Impressions are not external objects, nor do collections of them comprise external objects. But they are not internal either; they are all -- together with ideas, which are in essence only weaker perceptions -- that exists. There is no problem of the causal interaction of substances because there are no substances. There is no essential difficulty about representation, for all entities are of the same sort. Perceptions do not in themselves point beyond to anything that must inhere in or that must cause them; they are what they are, and we can know of nothing -- and thus nothing exists -- that transcends them. All the other philosophers considered here, even, emphatically, Foucher are searching for knowledge of the essence of substances. With Hume, the search for knowledge of qualities, powers, forms, forces. and essences or natures of substances founders at last. This is because nothing remains to which these terms can be applied; all that exists, for Hume, are impressions and ideas, which are perceived openly to be what they are and nothing more. [...]

And if the abandonment of the ontological pattern of substance and modification requires that new explanatory support be given for the relations of an idea's being in the mind and of a mind's being directly acquainted with an idea -- because these relations can no longer depend on the relation between a substance and its own modifications -- Hume can be seen as offering for this explanatory role the relation of an idea to the collection of perceptions of which it is a member.[...]

Hume thus completes the breakdown of Cartesian metaphysics.

But what have I here said, that reflections very refin'd and metaphysical have little or no influence upon us? This opinion I can scarce forbear retracting, and condemning from my present feeling and experience. The intense view of these manifold contradictions and imperfections in human reason has so wrought upon me, and heated my brain, that I am ready to reject all belief and reasoning, and can look upon no opinion even as more probable or likely than another. Where am I, or what? From what causes do I derive my existence, and to what condition shall I return? Whose favour shall I court, and whose anger must I dread? What beings surround me? and on whom have, I any influence, or who have any influence on me? I am confounded with all these questions, and begin to fancy myself in the most deplorable condition imaginable, inviron'd with the deepest darkness, and utterly depriv'd of the use of every member and faculty.

Most fortunately it happens, that since reason is incapable of dispelling these clouds, nature herself suffices to that purpose, and cures me of this philosophical melancholy and delirium, either by relaxing this bent of mind, or by some avocation, and lively impression of my senses, which obliterate all these chimeras. I dine, I play a game of backgammon, I converse, and am merry with my friends; and when after three or four hours' amusement, I wou'd return to these speculations, they appear so cold, and strain'd, and ridiculous, that I cannot find in my heart to enter into them any farther.

Here then I find myself absolutely and necessarily determin'd to live, and talk, and act like other people in the common affairs of life. But notwithstanding that my natural propensity, and the course of my animal spirits and passions reduce me to this indolent belief in the general maxims of the world, I still feel such remains of my former disposition, that I am ready to throw all my books and papers into the fire, and resolve never more to renounce the pleasures of life for the sake of reasoning and philosophy. For those are my sentiments in that splenetic humour, which governs me at present. I may, nay I must yield to the current of nature, in submitting to my senses and understanding; and in this blind submission I shew most perfectly my sceptical disposition and principles. But does it follow, that I must strive against the current of nature, which leads me to indolence and pleasure; that I must seclude myself, in some measure, from the commerce and society of men, which is so agreeable; and that I must torture my brains with subtilities and sophistries, at the very time that I cannot satisfy myself concerning the reasonableness of so painful an application, nor have any tolerable prospect of arriving by its means at truth and certainty. Under what obligation do I lie of making such an abuse of time? And to what end can it serve either for the service of mankind, or for my own private interest? No: If I must be a fool, as all those who reason or believe any thing certainly are, my follies shall at least be natural and agreeable. Where I strive against my inclination, I shall have a good reason for my resistance; and will no more be led a wandering into such dreary solitudes, and rough passages, as I have hitherto met with.

The common strain that binds together the attitudes and ideas which I call anti-intellectual is a resentment and suspicion of the life of the mind and of those who are considered to represent it; and a disposition constantly to minimize the value of that life.

[I]ntelligence is an excellence of mind that is employed within a fairly narrow, immediate, an predictable range... Intelligence works within the framework of limited but clearly stated goals, and may be quick to shear away questions of thought that do not seem to help in reaching them. [...]

Intellect, on the other hand, is the critical, creative, and contemplative side of mind. Whereas intelligence seeks to grasp, manipulate, re-order, adjust, intellect examines, ponders, wonders, theorizes, criticizes, imagines.

We stood talking for some time together of Bishop Berkeley's ingenious sophistry to prove the non-existence of matter, and that every thing in the universe is merely ideal. I observed, that though we are satisfied his doctrine is not true, it is impossible to refute it. I shall never forget the alacrity with which Johnson answered, striking his foot with mighty force against a large stone, till he rebounded from it, "I refute it thus."

There are some minds which give us the sense that they have passed through an elaborate education which was designed to initiate them into the traditions and achievements of their civilization; the immediate impression we have of them is an impression of cultivation, of the enjoyment of an inheritance. But this is not so with the mind of the Rationalist, which impresses us as, at best, a finely tempered, neutral instrument, as a well-trained rather than as an educated mind. Intellectually, his ambition is not so much to share the experience of the race as to be demonstrably a self-made man. And this gives to his intellectual and practical activities an almost preternatural deliberateness and self-consciousness, depriving them of any element of passivity, removing from them all sense of rhythm and continuity and dissolving them into a succession of climacterics, each to be surmounted by a tour de raison. His mind has no atmosphere, no changes of season and temperature; his intellectual processes, so far as possible, are insulated from all external influence and go on in the void. And having cut himself off from the traditional knowledge of his society, and denied the value of any education more extensive than a training in a technique of analysis, he is apt to attribute to mankind a necessary inexperience in all the critical moments of life, and if he were more self-critical he might begin to wonder how the race had ever succeeded in surviving. With an almost poetic fancy, he strives to live each day as if it were his first, and he believes that to form a habit is to fail. And if, with as yet no thought of analysis, we glance below the surface, we may, perhaps, see in the temperament, if not in the character, of the Rationalist, a deep distrust of time, an impatient hunger for eternity and an irritable nervousness in the face of everything topical and transitory.

Now, of all worlds, the world of politics might seem the least amenable to rationalist treatment--politics, always so deeply veined with both the traditional, the circumstantial and the transitory. And, indeed, some convinced Rationalists have admitted defeat here: Clemenceau, intellectually a child of the modern Rationalist tradition (in his treatment of morals and religion, for example), was anything but a Rationalist in politics. But not all have admitted defeat. If we except religion, the greatest apparent victories of Rationalism have been in politics: it is not to be expected that whoever is prepared to carry his rationalism into the conduct of life will hesitate to carry it into the conduct of public affairs.

But what is important to observe in such a man (for it is characteristic) is not the decisions and actions he is inspired to make, but the source of his inspiration, his idea (and with him it will be a deliberate and conscious idea) of political activity. He believes, of course, in the open mind, the mind free from prejudice and its relic, habit. He believes that the unhindered human 'reason' (if only it can be brought to bear) is an infallible guide in political activity. Further, he believes in argument as the technique and operation of reason'; the truth of an opinion and the 'rational' ground (not the use) of an institution is all that matters to him. Consequently, much of his political activity consists in bringing the social, political, legal and institutional inheritance of his society before the tribunal of his intellect; and the rest is rational administration, 'reason' exercising an uncontrolled jurisdiction over the circumstances of the case. To the Rationalist, nothing is of value merely because it exists (and certainly not because it has existed for many generations), familiarity has no worth, and nothing is to be left standing for want of scrutiny. And his disposition makes both destruction and creation easier for him to understand and engage in, than acceptance or reform. To patch up, to repair (that is, to do anything which requires a patient knowledge of the material), he regards as waste of time: and he always prefers the invention of a new device to making use of a current and well-tried expedient. He does not recognize change unless it is a self-consciously induced change, and consequently he falls easily into the error of identifying the customary and the traditional with the changeless. This is aptly illustrated by the rationalist attitude towards a tradition of ideas. There is, of course, no question either of retaining or improving such a tradition, for both these involve an attitude of submission. It must be destroyed. And to fill its place the Rationalist puts something of his own making--an ideology, the formalized abridgment of the supposed substratum of rational truth contained in the tradition.

Even without God, the idea of a natural sympathy between the deepest truths of nature and the deepest layers of the human mind, which can be exploited to allow gradual development of a truer and truer conception of reality, makes us more at home in the universe than is secularly comfortable. The thought that the relation between mind and the world is something fundamental makes many people in this day and age nervous, I believe this is one manifestation of a fear of religion which has large and often pernicious consequences for modern intellectual life.

In speaking of the fear of religion, I don't mean to refer to the entirely reasonable hostility toward certain established religions and religious institutions, in virtue of their objectionable moral doctrines, social policies, and political influence. Nor am I referring to the association of many religious beliefs with superstition and the acceptance of evident empirical falsehoods. I am talking about something much deeper--namely, the fear of religion itself. I speak from experience, being strongly subject to this fear myself: I want atheism to be true and am made uneasy by the fact that some of the most intelligent and well-informed people I know are religious believers. It isn't just that I don't believe in God and, naturally, hope that I'm right in my belief. It's that I hope there is no God! I don't want there to be a God; I don't want the universe to be like that.

My guess is that this cosmic authority problem is not a rare condition and it is responsible for much of the scientism and reductionism of our time. One of the tendencies it supports is the ludicrous overuse of evolutionary biology to explain everything about life, including everything about the human mind. Darwin enabled modern secular culture to heave a great collective sigh of relief, by apparently providing a way to eliminate purpose, meaning and design as fundamental features of the world.