Hume’s Edinburgh at eleven. By his early, to mid-twenties,

Skepticism of Reason


his body of work, philosopher David Hume professed his skepticism of reason,
science, and religion. Born in Edinburgh, April 26 of 1711, Hume was drawn to
philosophy at an early age, he attended the University of Edinburgh at eleven.

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By his early, to mid-twenties, he had written and finished his first published
work, A Treatise of Human Nature.1 In it, Hume emphasized a
skepticism of a priori knowledge, knowledge based on pure reasoning and
unrelated to experience. This empirical thinking led Hume to believe that
morality comes from experience in the world, not innate reason. This conclusion
that virtue was driven by these learned passions led him to famously state:
“Reason is, and ought only to be the slave of the passions, and can never
pretend to any other office than to serve and obey them.”2.

scholars of Hume’s era believed that the best way to seek truth and knowledge
was through pure reasoning. A methodology of thought put forward by Rene
Descartes a century earlier in his work, Discourse
on Method. In it, Descartes claimed the first step to his method was to
only accept what was undoubtedly true and then work up from there. For
Descartes, the only thing known for certain was that he existed; forced to go
off of only that, a priori knowledge and intense reasoning were used build.

Because of his experience and his methodology, Descartes espoused that reason
is key to knowledge, reason formed by the kinds of innate truths only available
through a priori knowledge, knowledge with no room for doubt or argument34.

It is precisely this Cartesian construction of reason that Hume is so skeptical

was an empiricist like the philosopher John Locke before him; the school of
empiricism followed that in order for one to understand matters of fact and
truth about the natural, physical world, one had to go out, experience and
study the world via a posteriori knowledge. This philosophical branch
emphasized truths that were observable and testable, akin to today’s physical
sciences. Hume’s support of the empirical put him at odds with other forms of
thought in his era, such as the rationalist thinkers holding to a priori
wisdom, as is demonstrated in his 1779 work, Dialogues Concerning Natural Religion.

work maintains a consistent assault on the usefulness of a priori knowledge and
the truths it reveals. Conclusions drawn from a priori knowledge are proven
true only when the opposite statement would be a contradiction. For example: if
someone has at least ten apples, then they must have more than nine apples;
because if they had less than nine apples, it would be a mathematical
contradiction. The issue Hume takes with this though is that in many cases, the
opposite of a statement may very well be wrong, but it’s not contradictory. A
claim that the sun will rise in the morning can’t come from a priori thought or
reasoning because a scenario where the sun doesn’t rise isn’t a contradiction5.

Dialogues Concerning Natural Religion,
Hume uses the idea of natural religion, the belief that God’s existence can be
proved through the natural world we live in, to further discuss the
relationship between reason and understanding. The work is set up as a dialogue
between three characters: Cleanthes, who supports the concept of natural
religion; Demea, who sways on the issue of natural religion but believes that
if it can be proven, it’d be through reason and not scientific thought or
inference; and Philo, who both refutes the concept of natural religion and the
efficacy of reason as a modality of thought in such a debate.6

character of Philo, the skeptic, is a very close representation of Hume in
terms of his views and beliefs. Philo doubts the theological arguments of his
companions that rely on innate reasoning, such as Demea’s argument of the chain
of causality. The chain is an idea he put forward, speculating that there’s a
chain of cause and effects that stretches back in time and that naturally,
there must be a first link in the chain, an unmoved mover who started it all in
motion7. Hume’s distaste for reason
is even summed up in the beginning of Dialogues
Concerning Natural Religion; when discussing when to introduce students to
theology, the skeptic character of Philo says:


Let us become thoroughly
aware of the weakness, blindness, and narrowness of human     reason, paying proper attention to its
uncertainty and its endless contradictions, even in ordinary everyday


The insults to reason continue intermittently through the
section. But Philo does concede that reason has a suitable application in the
field of mathematics because of the subject’s own self-evidence8.

Philo also calls into question many of the conclusions that can be drawn from a
posteriori knowledge as well. Hume uses the character to point out that this
inductive reasoning can’t prove anything as certain, only very probable; if
event A is often followed by event B, it’s a probable assumption that event A
will always be followed by event B, but it’s not a certain assumption as
there’s no definitive cause between event A and event B, only a correlation9.

because of his diminished confidence in the certainty of inference, and his
disregard for a priori reason Philo is such a tough skeptic in the dialogue.

Hume writing as Philo proclaims subjects such as the qualities and existence of
God, the beginnings of the universe, and thoughts of the afterlife have “gone
quite beyond the reach of our faculties” due to the lack of personal experience
with them; and instead, inductive thought is best applied to daily concepts
like trade, politics, and morals.10 The idea is that the more
examples of cause and effect that are seen or experienced, the more evidence
there is to base inductive logic off of, and the stronger an empirical case it
will be. In the examples of argument by design, the belief that the natural
world itself is evidence of God’s intelligent design, Cleanthes proposes that
the universes mechanical-like nature, its level of perfectness, it’s beauty and
complexity, are all examples that prove God created the universe and therefore
prove the existence of God through the universe. Philo in response to this
dismantles every argument posed to him, often by showing the lack of evidence
and certainty in the empirical proof submitted.

the case of reason and morality, Hume proposes an approach that focuses on
immediate experiences and inferences. Human desires and necessities are
responsible for morality in the form of passions that reinforce themselves
through action. Desire motivates an action, that action either results in
pleasure or pain for the individual, the mind connects these as cause and
effect through inductive inference, and a passion is created. In his Treatise on Human Nature he states:


impression first strikes upon the senses, and makes us perceive heat or cold,

or hunger, pleasure or pain of some kind or other. Of this impression there

a copy taken by the mind, which remains after the impression ceases; and

we call an idea. This idea of pleasure or pain, when it returns upon the soul,

the new impressions of desire and aversion.11


It’s only reactions of pleasure or pain
that elicit the formation of a virtue or vice, respectively. In this sense,
passions are the driving force behind the morality that affects human action.

morals are the passions we develop that are beneficial either to ourselves or
others, and the things we would deem immoral are often behaviors that are
harmful. This implies that our morals come from a place of pragmatism, but are
somehow more than just stark self-interest. People admire the moral qualities
of honor and courage even in their enemies, and whole cultures sing praises of
the virtues of peoples long gone; we have a natural concern for the welfare of
others, and an investment in our action’s effects on them12.

This highlights another dynamic in Hume’s treatment of reason in regards to
morality: moral actions aren’t by nature reasonable, nor are immoral actions
devoid of reason13.

not to say reason has no place in morality though. In Hume’s construction of
morality, reason has been relegated to an advisory role. Reason acts as judgment
to determine a course of action, while passion supplies the drive. To return to
Hume’s famous line from A treatise of
human nature, “Reason is, and ought only to be the slave of the passions,
and can never pretend to any other office than to serve and obey them.”14.

an empiricist thinker, Hume harbored reservations toward the use of reason as
an accepted method to understand the world. In addition to this, he also held
healthy skepticisms about many proofs of induction using a posteriori
knowledge, concerned about the availability of experience and information when
discussing metaphysics and theology15.

His doubt and critiques of information gleaned from either source gave Hume a
critically skeptical view of philosophy. A view through which he expressed his
concerns on non-empirical thought repeatedly, proposing that reason is an
inadequate tool for understanding concepts like, morality, matters of fact, and
even theology.






Descartes, Rene. Discourse on Method. July
1, 2008.



Hume, David. My own life. Stanford Dingley: Mill
House Press, 1927.


Hume, David. A treatise of human nature. London:
Allman, 1817.

Hume, David, Esq. Dialogues Concerning Natural Religion.

William Strahan, 1779.


Kant, Immanuel. Critique of Pure Reason up to the end of the
Analytic. 1781.


Martin, Marie A. Utility and Morality: Adam Smith’s Critique
of Hume. Vol. XVI. Hume

Society, 1990.


Morris, William Edward,
and Charlotte R. Brown. “David Hume.” Stanford Encyclopedia of

Philosophy. May 21, 2014.


Winters, Barbara. Hume on Reason. Vol. 5. Hume Society,



1 Hume, David. My own life. (Stanford Dingley:
Mill House Press), 1927. 32-34


2 Hume, David. A treatise of human nature. (London:
Allman), 1817. 416


3 Winters, Barbara. Hume on Reason. Vol. 5. (Hume Society),
1979. 27


4 Descartes, Rene. Discourse on Method. (,
July 1, 2008.


5 Hume, David, Esq. Dialogues Concerning Natural Religion.

(William Strahan), 1779. 39


6 Ibid.


7 Ibid. 38


8 Ibid. 3


9 Kant, Immanuel. Critique of Pure Reason up to the end of the
Analytic. 1781. 114


10 Hume, Dialogues Concerning Natural Religion. 5


11 Hume. A treatise of human nature. 8


12 Martin, Marie A. Utility and Morality: Adam Smith’s Critique
of Hume. Vol. XVI. (Hume         Society),
1990. 108


13 Hume. A treatise of human nature. 456-59


14 Ibid. 416


15 Ibid.