On Hume and Metaphysics

Regarding Hume's views on the futility of metaphysics to describe reality

On Hume and metaphysics

Metaphysics is the philosophical practice of employing reason to produce a coherent structure to reality. Plato presents a system of at least two levels, splitting the world of appearance of our everyday reality, from the world of ideal Forms of which our existence is a pale reflection. Plato suggests that we may come to understand this unseen world by peering more closely into our own experience. By understanding the drama of our existence, we may make reasoned analogies from our sense experience to the ideal, and thereby move towards knowledge and wisdom.

For Hume however, metaphysics was a futile enterprise. He states it is capable of achieving only imagined insights that fade like dust in the real world, and urges men to direct their endeavors to useful action for society. He proposes to show the exact manner in which such pursuits must fail, only then will men turn their thinking to more profitable endeavors. A closing statement of his sums this up well:

"When we run over libraries, persuaded of these principles, what havoc must we make? If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion."

Hume and science

Hume's views are a consequence of the ascendancy of science, and the emphasis that science placed on sense experience to arrive at knowledge about the world. In line with scientific thinking, Hume places no value in what is not immediately apparent to our senses.

And so we find that Hume describes perfectly how the world must be if there is no metaphysics, for he makes no distinction between reality and appearance. For Hume, all reason derives from sense experience, therefore there is nothing beyond the sensual world for reason to drive towards.

Hume on logical and empirical knowledge

Hume splits all propositions of reason into the logical and empirical. Logical propositions concern matters of mathematics. They are demonstratively certain, but are simply true by definition, and therefore provide no special insight into the nature of things.

Hume concludes empirical propositions can provide no special insights into the nature of things either. He describes how observation only ever provide insight into what might be the case, never what is true necessarily. In other words, it is only by custom and habit that we conclude observations regarding the physical world will continue into the future. He uses a particularly extreme example to state his case, showing how there is nothing about the sun rising that allows us conclude it will rise tomorrow.

Hume on the external world

By reference to this line of reasoning, Hume calls into question all knowledge regarding the external, internal and moral worlds. We assume external objects have a permanent identity that persists through time, but its only by reference to imagination that we conclude this. In a similar way, he denies the existence of a permanent self, concluding by reference to his experience that it is nothing more than a bundle of sensations. And in denying reason its capacity for insight, he calls into question any conclusion we may make regarding morality.

Hume on skepticism

For Hume then, it is clear his conclusions must end in a powerful skepticism. Reason as a vehicle to guide ourselves in the world is clearly futile, and he advises instead to abandon it and let custom and passion guide our life. He places the center of our means for satisfying our desires in emotion, concluding 'that reason must be the slave of our passions'.

The extremity of Hume's views then are a direct consequence of lacking a metaphysics to guide his thinking. He remains forever locked in his first person subjective perspective, needing to settle for opinions regarding the world that never quite settle on truth.

This distinction between opinion and truth is exactly the conclusions that Plato stated regarding the physical world. Plato agrees with Hume's conclusions regarding sense knowledge, arguing they can always be X and not X, at different times to different observers in different contexts. This means we may never arrive at knowledge regarding physical objections, only opinion.

On the necessity of metaphysics

Where Hume and Plato disagree is in the metaphysical role that reason plays. Plato argues that the objects of reason are the aforementioned Forms. A Form is its own essence, they are the most simple and perfect example of itself that are independent of particulars, and therefore exist outside space and time. This is why metaphysics is necessary to account for it.

By granting the objects of reason existence, one grants them the ability to provide insights regarding the real world. It is by reference to Forms that we are able to move beyond self-evident truths, such as 'All bodies take up space', into original truths that are not contained in their definitions, such as 'Red and blue mixed together make yellow'. And in similar fashion, it is by reference to these Forms that we are able to make original insights about the world around us, about our inner being and about how we act in the world, all categories of knowledge that Hume denied.