1. David Hume Scottish philosopher and historian (1711-1776)
Perhaps the greatest philosopher to write in the English language.
An empiricist, a skeptic, a naturalist, an anti-rationalist
Known for his contributions to metaphysics, epistemology, philosophy of religion, ethics, politics, economics
Created a lot of problems and puzzles

2. David Hume Outspoken opponent of organized religion
Suspected of atheism for his entire career; never held an academic position
Known for being a very cheerful and sociable man
Nicknames: “le bon David” and “the saintly infidel”
Had his strongest attacks on religion published after his death

3. David Hume Best friends with Adam Smith, the founder of economics
There was a big scandal after Hume died, when Smith published an admiring and emotional account of the last days of Hume’s life
“Upon the whole, I have always considered him, both in his lifetime and since his death, as approaching as nearly to the idea of a perfectly wise and virtuous man, as perhaps the nature of human frailty will permit.”
Hume the terrible atheist was cheerful and in good humor on his deathbed

4. Rationalism
“Every rational creature, it is said, is obliged to regulate his actions by reason; and if any other motive or principle challenge the direction of his conduct, he ought to oppose it, till it be entirely subdued, or at least brought to a conformity with that superior principle.”
As with Plato, reason is supposed to make decisions and motivate the agent

5. Hume’s anti-rationalism
“reason alone can never be a motive to any action of the will”
“it can never oppose passion in the direction of the will.”
When it comes to motivation and action, reason alone is “perfectly inert”

6. Hume’s anti-rationalism
If reason alone cannot motivate us or direct our actions, then what does motivate us?
‘Passions’: sentiments, affections, emotions, desires, appetites, feelings, concerns, interests, goals, preferences
Hume is often called a “sentimentalist”
The basic idea: if you don’t care at all about some fact, then learning about it won’t influence your actions. Without the presence of a sentiment, reason can do nothing.

7. Rationalism and Sentimentalism
The dispute is over the following questions:
Can reason alone ever motivate us? Or does there have to be some sentiment involved?
Can actions or motives be judged as being reasonable or unreasonable? Or do they have nothing essential to do with reason?

8. Hume’s Fork There are two types of reasoning:
1. Demonstration: abstract relations of ideas; mathematics and logic.
2. Probability: matters of fact; cause and effect; based on experience and observation
Neither one of them has the power (all by itself) to influence our actions

9. Demonstration (math, etc.)
“Mathematics, indeed, are useful in all mechanical operations, and arithmetic in almost every art and profession: But it is not of themselves they have any influence: Mechanics are the art of regulating the motions of bodies to some designed end or purpose”
“A merchant is desirous of knowing the sum total of his accounts with any person: Why? but that he may learn what sum will have the same effects in paying his debt, and going to market, as all the particular articles taken together.”
These discoveries of reason only influence us if we have some prior concern (i.e., a sentiment).

10. Probability (cause and effect)
When we discover that two things are causally related, our actions can be influenced, but only if we already have some relevant concern.
“It can never in the least concern us to know, that such objects are causes, and such others effects, if both the causes and effects be indifferent to us.”
When we find out that something causes pleasure, that discovery influences our actions, but that’s only because we already have an emotional attachment to pleasure.
“But it is evident in this case that the impulse arises not from reason, but is only directed by it. It is from the prospect of pain or pleasure that the aversion or propensity arises towards any object”

11. General conclusions
“reason alone can never produce any action, or give rise to volition”
And this means that reason alone cannot oppose passion for control of the agent.
The only way to oppose passion is to send out a contrary motivational impulse; but we just showed that reason can’t have this influence
“We speak not strictly and philosophically when we talk of the combat of passion and of reason. 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.”

12. The “slave of the passions”?
There’s only one role that reason can play: the discovery of truths.
This means that reason can provide information to the passions
information like “this will cause pain”
But this only has an influence if there are some passions relevant to the information.
If I don’t care about this information, reason can’t motivate me.

13. The Representation Argument
Reason deals exclusively with the discovery of truth and falsehood
Truth and falsehood is nothing but the faithful representation of the facts.
A sentence is true when it faithfully represents the facts; it’s false when it disagrees with the facts
Passions (and actions) are not representational; they don’t represent the facts as being a certain way
So passions (and actions) cannot be either true or false.
So they cannot be either contrary or conformable to reason.

14. The gist of the argument
Passions are not the sort of thing that can be true or false.
They don’t even purport to represent the world.
And reason is just the discovery of truth and falsehood.
So passions can’t be reasonable or unreasonable.

15. Passions contrary to reason?
You can call passions reasonable or unreasonable – but only in a sense
Suppose a passion is founded on some false belief.
I desire to drink this because I believe that it is water. In fact, it is deadly poison.
Then, in a sense, the passion is contrary to reason.
But really it’s the belief that it is contrary to reason.

16. Passions contrary to reason?
And when the passion isn’t founded on a false belief, then there is no sense in which it is contrary to reason
“It is not contrary to reason to prefer the destruction of the whole world to the scratching of my finger. It is not contrary to reason for me to chuse my total ruin, to prevent the least uneasiness of an Indian or person wholly unknown to me. It is as little contrary to reason to prefer even my own acknowledged lesser good to my greater, and have a more ardent affection for the former than the latter.”

17. Instrumentalism This a view about practical reason.
It’s used in economics.
An action is rational or irrational to the extent that it serves the preferences of the agent – no matter what those preferences are.
If you have ludicrous or abominable preferences, then that doesn’t make you irrational.
The only thing that’s irrational is to frustrate your own goals.

18. Nihilism This is an extreme rejection of practical reason.
Actions cannot be either rational or irrational.
Even if you frustrate your own goals, or act contrary to your own preferences, that’s not irrational.
Reason has nothing to do with action.

19. What about internal conflict?
Remember: this is why Plato drew the distinction between these different elements of the soul – all of them capable of controlling the person
Hume says that certain passions are ‘calm’. They don’t cause violent disturbance or sensible emotions in the mind.
Internal conflict isn’t between reason and the passions – it’s between calm passions and violent passions.

20. Calm passions There are two types:
Natural instincts (benevolence and resentment, the love of life, and kindness to children)
General appetite for one’s good, and aversion to one’s evil (avoiding pain, seeking pleasure)
These are real passions, but they are known more by “their effects than by the immediate feeling or sensation”

21. Calm passions
Because these passions are calm, people mistake them for reason.
Reason doesn’t produce sensible emotion, and neither do these calm passions, so people end up confusing them with each other
Sometimes violent passions overcome us, and we have to try to subdue them.
But it is our calm passions (not our reason) that oppose our violent passions.
Strength of mind is just “the prevalence of the calm passions above the violent”

22. Why this matters
It seems like our moral judgments have the power to influence our behavior.
But if reason lacks this power, then moral judgments can’t come from reason.
Instead, they must come from our passions.
The debate between rationalists and sentimentalists becomes a debate about the status of moral judgments.