What’s in it for me? Uncover a philosophical classic and challenge everything you thought you knew in the process.
We moderns pride ourselves on our ability to reason.
It’s through reason that we’ve discovered nature's secrets and set ourselves apart from the rest of the animal kingdom.
It’s also through reason that we distinguish ourselves from the mythological dogmatism that defined previous eras.
But what makes us so sure that humans really are so reasonable?
Is this belief founded on reason itself.
.
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or is it just another myth?
Well, if we could ask Hume, he’d say that our pretense to be rational beings is pure hubris.
In his Enquiry, Hume carries reason to its breaking point by explaining why we actually have no rational basis for believing in almost any of the things we do.
By following Hume’s logic, these blinks explain how he arrives at his remarkable conclusion that, whether we like it or not, humans are moved more by animal instinct than anything else.
In these Blinks, you’ll learn what the game of billiards can teach us about the nature of cause and effect; why it’s never rational to believe in miracles; and why we have absolutely no reason to believe the sun will rise tomorrow.
David Hume was born in the eighteenth century, slap-bang in the middle of the Enlightenment.
All knowledge derives from experience.
With the scientific method ascending to prominence in Europe, it was a time of unparalleled optimism in the power of reason to discover truth.
Over the course of this fruitful period, many great thinkers like Descartes, Locke, and Berkeley came up with novel ways to try and ground their philosophies in reason.
But, despite their different approaches, all these philosophers made the same fundamental error – they all attempted to shoehorn their theological commitments into their rational philosophies.
In many respects, Hume’s empirical philosophy responds to these developments.
On the one hand, Hume continued the rationalist thread of the Enlightenment by imploring us to justify our beliefs with reason.
On the other hand, by limiting the scope of reason to the realm of human experience, Hume decoupled reason from the realm of speculation that requires theological beliefs, and thereby set the stage for a purely secular philosophy.
The key message here is: All knowledge derives from experience.
Hume’s entire empirical philosophy is built on one foundational distinction: the distinction between impressions and ideas.
Impressions are direct sensory experiences and emotions.
For example, when you see the color red or when you feel angry, you’re experiencing direct impressions.
Ideas, on the other hand, come from the imagination or from memory.
You have an idea when, for example, you close your eyes and conjure the color red or the feeling of anger.
As they’re abstracted from direct experiences, we experience ideas as diluted and vaguer than the original impressions.
Now, since ideas are copies of impressions, it follows that we can’t have an idea until we’ve experienced the impression.
You couldn’t, for example, really know what love is until you’ve actually been in love.
Of course, you might object that you have all sorts of ideas that you’ve never directly experienced.
With help from the imagination, you can summon all manner of fictional worlds full of monsters and strange landscapes that you’ve never encountered in reality.
This is true.
But, as Hume points out, the ideas of the imagination are all built out of simpler impressions that we’ve directly experienced.
For example, we can imagine a mountain made of gold by mixing the simpler ideas of gold and mountain in our heads to form a new idea.
Since all ideas are derived from simple impressions, this provides us with a simple method for determining whether or not an abstract idea, such as God, has any meaning.
All we need to do is point to the impression that produced it.
If no impression can be found, then we have good reason to reject the idea as empty and groundless.
If everything we know comes from experience, this immediately raises a problem.
We have no experience of a necessary connection between events.
How could we ever make predictions about the future?
After all, we can never experience the future.
Thankfully, we can make use of a handy principle called cause and effect.
In the past, we’ve learned that certain events cause other events.
All we need to do is transpose that knowledge into the future and we have a method for making predictions about what’s going to happen.
So, let’s imagine you’re playing a game of pool.
You’ve just hit the white ball with your cue and sent it shooting down the table toward a green ball.
What do you expect is going to happen when they meet?
You expect the green ball to move, right?
That’s what it’s always done in the past.
But think about it.
How can you be sure that this time around the green ball isn’t going to remain motionless or disappear in a puff of smoke?
The reason you feel so confident is that you believe that, by nature, the white ball necessitates that the green ball will move when it’s struck.
The question is: are you justified in believing this?
The key message here is: We have no experience of a necessary connection between events.
When we think about the relationship of cause and effect, we imagine it as a necessary relationship.
In other words, we believe that there’s something in the cause that by the laws of nature produces a certain effect and couldn’t possibly produce any other effect.
For example, if you were to put your unprotected hand in a fire, it would burn.
You don’t believe it would freeze your hand or turn it to stone because it’s not in the nature of fire to do that.
But where does this idea of necessity come from?
Remember, Hume’s empirical method gives us a handy way of identifying where an idea comes from.
We need only to point to the impression that caused it.
So, where then, have we experienced this idea of necessity?
Well, nowhere.
We’ve never experienced necessary causation.
All we’ve ever experienced is one event frequently followed by another.
For example, we’ve experienced fire followed by burning plenty of times, but not once have we ever experienced fire necessarily followed by burning.
There’s nothing in an experience itself that tells us that an effect is the one and only effect that possibly could have arisen.
Since we’ve no experience of necessity, Hume invites us to rethink our idea of cause and effect as merely constant conjunction between events.
In other words, all we ever experience is that some events frequently follow other events.
Inductive reasoning can’t be justified rationally.
OK, so we might not directly experience a necessary link between cause and effect.
But what if we could use reason to find out if there’s a connection?
Well, let’s give it a go.
When we’re trying to determine a general theory, like the necessary connection of cause and effect, we usually use inductive reasoning.
This is the form of reasoning used when we draw general conclusions from a synthesis of several specific observations.
It’s the mode of thinking operating in the background when we make inferences about the future based on past observations, like inferring that fire will burn us again in the future because it has done so in the past.
But Hume famously criticized the validity of this form of reason.
Inductive reasoning, he argues, is viciously circular.
The key message here is: Inductive reasoning can’t be justified rationally.
Let’s consider an example that pretty much everyone agrees with.
We all believe that the sun is going to rise tomorrow morning, and then the morning after that.
Why do we believe this?
Well, based on inductive reasoning.
The sun has risen every other day of our lives, so we feel pretty confident that it’ll rise tomorrow as well.
You might think this is solid reasoning.
The problem is, in order for the argument to work, we need to make a big assumption.
We need to assume that things will continue to behave in the future as they’ve done in the past.
This assumption is impossible to prove.
We can’t experience the future directly, nor can we divine the underlying causes of the universe with absolute certainty.
Our laws of physics are based entirely on past observation, and for all we know, they could change overnight.
Now, maybe it strikes you as just plain obvious that the laws of physics are going to remain stable into the future.
They’ve remained stable all your life, so they’re probably not going to change now, right?
But notice, if you try to justify the future stability of the laws of physics by pointing to the past, then you’re using inductive reasoning!
And, what did Hume teach us about inductive reasoning?
That it only works if we take it for granted that the future will be like the past.
Therefore, you’re assuming the very thing you’re trying to prove!
In philosophy, this is called vicious circularity.
Inductive reasoning, then, can’t be justified rationally.
We have no choice but to accept the remarkable conclusion that we have no rational justification for believing the sun will rise tomorrow.
Humans think instinctually rather than rationally.
So Hume has shown that we have no rational basis for making any inferences about the future.
But don’t let this put you off planning for tomorrow!
Hume was the first to admit that there’s a natural limit to this kind of skeptical reasoning.
We might not be rationally justified in believing the things we do, but that doesn’t stop us from believing them.
All of us, and that includes philosophers, use inductive reasoning every day in pretty much every action we take.
If we didn’t do this, we simply wouldn’t be able to live.
For this reason, Hume concludes, humans are guided more by habit and necessity than they are by reason.
The key message here is: Humans think instinctually rather than rationally.
Habit, not reason, is why we believe that causes are necessarily connected with their effects.
After witnessing one event followed by another so many times, our minds form a habitual connection between the two events.
So when we see the first event, our minds lead us to expect the second.
That’s all there’s to it.
Consider, for example, the way young children learn.
Clearly, children are able to form associations between events, even if they don’t do it consciously.
They learn, for instance, that when they touch a candle’s flame, it hurts.
So, eventually, they learn to avoid touching flames altogether.
Do children discover this through some abstract process of reasoning?
Of course not.
Children don’t learn through reason but through instinct.
And, it’s a good thing that they do too, because instinct is a lot more reliable than reason is!
Could you imagine if humans experienced the world as a chain of completely disconnected events, and we had to piece the world together through a conscious process of reasoning from cause to effect before we made any decision?
Humans would have died out a long time ago, that’s for sure.
This natural instinct for inductive reasoning isn’t unique to humans either.
Animals, too, learn from their experiences and come to associate causes with effects.
Dogs, for instance, learn to associate the sound of a whistle with their owner, or the sight of their bowl with food.
It’s clear that dogs infer something that’s beyond their immediate perception, and this inference is based on past experience.
It turns out, then, that the way humans think is far closer to our animal cousins than we may care to admit.
We too are creatures of habit and instinct.
Human action is both free and determined.
If it’s true that humans are guided more by instinct than by reason, this raises another problem.
If reasoning doesn’t have any influence on our behavior – if we’re just animals governed by blind instinct – then what room does that leave for human freedom?
This is really just a reformulation of the free will vs.
determinism debate, which has been raging in philosophy for centuries.
The debate considers how it’s possible to reconcile the fact that human actions are causally determined – in this case by our instincts – with our conviction that we have freedom over how we act in any given situation.
The concepts of free will and determinism seem completely incompatible with one another.
But Hume, surprisingly, doesn’t see it this way.
For Hume, this whole centuries-long debate is simply the result of confusion over the words that philosophers have been using.
He suggests that if we only redefine the concepts of free will and determinism along the lines of his theory of cause and effect, then it’ll be plain as day that free will and determinism are compatible.
The key message here is: Human action is both free and determined.
As we’ve seen, Hume argued that the concept of necessary causation is derived from our habits and not from the external world.
By doing this, Hume has opened up the possibility that events could produce any number of effects other than the ones they actually do.
Thus, for example, we could say that a flame causally determines wax to melt insofar as wax frequently melts when it comes into contact with a flame.
However, the wax doesn’t melt necessarily and it’s always possible that some other effect will ensue.
What’s more, just as physical processes exhibit regularities between cause and effect, human action also exhibits regularities between inner motivations and outer behavior.
For example, when people feel hungry, they’re generally moved to find something to eat.
And, when people feel angry, they often raise their voices.
We say that people’s inner feelings determine their behavior because we observe that certain kinds of behavior frequently follow from certain kinds of inner states.
However, there’s no necessary connection between the two.
It’s perfectly possible that we don’t bother eating despite being hungry or that we keep our voices quiet despite being angry.
Human behavior is therefore on par with physical processes in the universe.
Both are determined insofar as they both exhibit regularities of cause and effect.
And, yet there’s no necessity between cause and effect in either domain.
It’s this space between our inner motivations and outward behavior that’s the proper domain of free will.
It’s never rational to believe in miracles.
One of the reasons why Hume’s empirical philosophy was so radical and controversial back in the eighteenth century is that it provided rational grounds for rejecting miracles.
Miracles were widely believed at the time and were often taken as evidence for religious doctrines.
Consider this curious example reported by a French cardinal in the seventeenth century.
While on one of his travels in the French provinces, the cardinal wrote of having encountered a man who’d apparently regrown his leg.
The townsfolk insisted that the man had gone many years with only one leg, but had recovered the missing limb after rubbing holy oil over the stump.
Now, this story might seem quaint to our modern ears.
But, even if we no longer believe in miracles, we’ve all swallowed a few tall tales in our time.
It’s an essential skill, especially in our era of fake news, to be able to evaluate the testimony of others.
And, believe it or not, Hume’s eighteenth-century philosophy provides us with a powerful method for doing just that!
The key message here is: It’s never rational to believe in miracles.
Testimony is undoubtedly one of the most useful and most common sources of human knowledge.
Through testimony, we expand the horizon of our personal experience by incorporating the experiences of others.
But, of course, not all testimony is reliable.
People make mistakes.
People exaggerate the truth.
People get sucked into a good story.
We know from experience that humans have a great fondness for spinning yarns – especially ones that include a touch of the unbelievable.
So, how can we evaluate testimony?
Well, when it comes to the more mundane species of testimony – news – this task is fairly straightforward.
We can judge whether the testimony is plausible by comparing it to what we’ve already experienced in the past.
But, when it comes to stories of spectacular and miraculous events, verification by experience isn’t feasible.
The event is usually so singular that it can’t be repeated.
Nor can you compare it to any event that you’ve ever experienced.
You’ve simply never experienced a dead body to come back to life, or a human limb regrowing.
What that means is, the only evidence you have in favor of the miracle is testimony, which you know by experience isn’t always reliable.
On the other hand, we have an apparently stable law of nature that we haven’t once in our entire lives experienced failing.
Since our experience of the laws of nature is always far more reliable than our experience of testimony, it’s always more rational to disbelieve an account of a miracle.
A healthy amount of skepticism contributes to a good life.
Hume’s empirical philosophy is based on the principle that the only way we can learn about the world is through sensual experience.
Of course, Hume admits, this requires that we trust our senses to represent the world as it really is – and it’s far from obvious that they do.
We know, for example, that our senses often deceive us, such as when a boat’s oar appears crooked in the water, or when an object appears doubled when it’s held too close to the eyes.
We also can’t be sure what proportion of our sensory experience is contributed by the mind.
Some philosophers argue that qualities like color and sound are products of the mind.
And, who knows – maybe everything we experience is just an idea in our heads.
So, our conviction that there’s an external world out there isn’t something we can know for certain.
However, as Hume points out, this kind of radical skepticism is impossible to live by.
If we tried to put radical skepticism into practice and suspend belief in everything, it would completely incapacitate us.
That’s why, Hume argues, we need to set practical limits on skeptical philosophy.
The key message here is: A healthy amount of skepticism contributes to a good life.
We can’t help but trust our senses and believe in the existence of an external world.
This is simply another case of habit winning out over reason.
But, if it’s not possible to consistently put skepticism into practice, then what value does it have?
Is it just a game that philosophers play?
Well, there’s one sense in which radical skepticism can positively benefit your life.
Once you’ve gone through the process of doubting everything, including reason itself, it’ll shake you from your youthful self-assuredness and leave you feeling humbled.
You can then carry this humility into the rest of your life by incorporating modest skepticism into all your opinions.
In other words, take everything with a pinch of salt.
When you live by a principle of modest skepticism, it can actually contribute to a healthy life.
For one, it can help to undo prejudicial or dogmatic thinking that you might have inherited when you were young.
Humility also teaches us to be better learners and better listeners by making us more open to what others have to say.
Only by being mindful of our tendency to fall into error will we have a chance of protecting ourselves from false ideas and illusions.
Human reason isn’t a perfect, divine faculty, but an all-too-human one.
Final summary
Reason is profoundly limited and fallible, and it’s unable to ground any of our beliefs with any certainty.
Thus, most of the things we believe have nothing to do with reason but are simply the products of instinct and habit.
That being said, when employed modestly within the realm of everyday experience, reason can improve our lives by helping us to evaluate ideas and steer clear of falsehoods and superstitions.
Actionable advice: Incorporate a principle of modesty in all your beliefs.
Given the limited and fallible nature of human reason, it’s a good idea not to hold your opinions too firmly.
You ought to hold off from making wild speculations that you can’t prove.
You should try to find evidence for your beliefs, and suspend belief when you can’t provide any.
And, you ought to accept that you may be wrong and that you can learn from the experiences of others.
Remaining modest in your beliefs is the only path to any reasonable degree of truth and knowledge in this world.