Morality, Customs, Laws and Hume's Law

Is it logically sound to extrapolate prescriptions from descriptions? How does this manifest in our worldviews and daily interactions? And what does it tell us about the relationship between morality, customs and laws?

Today we continue our exploration of logical tools that we can use to refine and test arguments – both our own and those of others – in order to have better conversations in our public squares. Today’s tool is called Hume’s Law, and as the name implies, it comes to us courtesy of David Hume, the highly influential Scottish philosopher who lived in the 18th century.

Hume was a prominent figure during the Age of Enlightenment, in which knowledge coming from reason or sensorial evidence was king. Those were the big themes of Enlightenment. However, these two categories were somewhat at odds. On one hand, rationalists argued for reason as the main source of knowledge. On the other, empiricists placed more stock in evidence from observation.

Hume was an empiricist. He questioned the relationship between cause and effect. He thought that we really couldn’t perceive it; that observing a chain of events numerous times can’t rationally lead to assuming that they are causally related. This is the problem of induction, which we mentioned briefly in our last episode (article, podcast). He also affirmed that reason doesn’t drive morality, but that feelings or sentiment do. This is important; we’ll return to this point later. And in a sense, Hume’s skepticism, along with, ironically, the side effects of Kant’s attempts to refute it, gave way to the deconstructions, redefinitions and relativism that characterizes today’s post-modernism.

The influence of David Hume is far-reaching, crossing lines and sides that otherwise don’t mingle. In different ways, he influenced Christian theologian and philosopher Soren Kierkegaard, Jewish pantheist and rationalist Baruch Spinoza, Imanuel Kant, Karl Popper, and many others. There is a long list of philosophers who either were influenced by Hume or built at least part of their legacy on refuting some aspect of Hume’s.

Hume’s Law

But today I want to focus on one contribution by Hume which I find really important to logical thinking, which applies across various worldviews, and that is the is-ought problem. Hume first articulated this as a question stemming from an observation, but today it’s more commonly known simply as Hume’s Law. His observation was that those who document moral systems are prone to going from facts or descriptive statements – how things are – to prescriptions, or how things should be, with no rational process behind this jump. This observation has spawned a deep discussion in the realm of ethics, the branch of philosophy that studies morality or the concept of right and wrong.

A very simple way to articulate Hume’s Law is this: one shouldn’t derive an “ought” from an “is”. In other words, descriptions shouldn’t automatically imply prescriptions. This is a very powerful concept because in practical terms, it exposes a logical fallacy. Whenever a fact is used to justify a commandment with no logical arguments entailing it, we witness a naturalistic fallacy. Here’s an example: “Digital services aren’t taxed today, so they shouldn’t be taxed.” There are no logical arguments connecting the fact to the command or truth statement; this is just an opinion. Here’s another: “This road has never been a toll road; therefore, this road shouldn’t be a toll road.” The history of the road doesn’t provide enough evidence in and of itself to not turn the road into a toll road; this is just another opinion.

Here’s another one: “Reproduction occurs through sex. Therefore, people should only have sex to make babies.” One more time, the fact is accurate – reproduction does occur through sex. But there is no logical progression connecting that descriptive statement to the prescriptive commandment. Here’s one more. “I can freely enter and leave the country; my right to do so shouldn’t be restricted.” The reason Canadians can freely enter and leave the country is that mobility rights are in fact enshrined in Section 6 of the Canadian Charter of Rights and Freedoms. Our Constitution also defines when and why can the government temporarily restrict these rights. The right doesn’t exist because I can travel; I can travel because the right exists.

That last example is interesting, because in ordinary circumstances, the conclusion is true; again, we do have mobility rights. But like everything in logic, Hume’s Law is concerned with the correctness of inference, not with the veracity of the conclusion. The conclusion may be true, but the process to infer it from the premise is not correct in this case.

Here’s another one that I face often. Sometimes people will ask me, “If the Bible teaches that early Christians had everything in common, why aren’t modern churches like that?” And the short answer is that the early church in the book of Acts is described in the Bible. It’s a description, not a prescription. Not a commandment. Today, specific churches or groups of people may choose to imitate this example, but it’s not a command. Generally speaking, unless explicitly followed by a command, a biblical example is just that – an example. Descriptions do not automatically spawn prescriptions; assuming otherwise just breaks Hume’s Law. And in fact, correctly differentiating between descriptions and prescriptions is a key principle of Bible interpretation.

As a sidebar, there is a separate problem of the scope of prescriptions. Another question I get often is, “How can Christians eat shrimp if the Bible forbids it, and how can I take biblical commandments seriously when not even Christians obey them uniformly?” And the short answer is that biblical prescriptions don’t apply uniformly to all ages or all populations. It’s the same as with the Canadian Criminal Code. If you looked at it 50 years ago, you would see that suicide was illegal. That was repealed in 1972, and then in 2016 the Code was amended again to decriminalize medical assistance in dying. I’ll talk more about that in an upcoming episode. But in a similar vein, if you arbitrarily pick a prescription from an Old Testament book in the Bible, it might have applied to ancient Israel only, or to Christians only, or to all of humanity. The context and the scope of the prescription matter.

That was just a sidebar. Going back to our main topic, sensible Bible interpretation respects Hume’s Law.

There are many other fallacies that are closely related to Hume’s Law, although strictly speaking they’re all different. For example, in the statement, “Animals are polygamous. Humans should be polygamous.” the fact is taken from nature. This type of violation of Hume’s Law is known as an appeal to nature. If something is observed in nature, then that’s how it should be. In this particular example, we don’t specify that some animals are naturally polygamous, whereas some others have lifelong partners. We can’t infer a moral law from nature alone.

There’s also the opposite of Hume’s Law, the moralistic fallacy, also known as “wishful thinking”. Here I describe and justify the way things are based on my belief of what’s right. In other words, from an “ought” I seek to enforce an “is.” A popular and somewhat disturbing example is this: “This is a one-way street, so I don’t need to look both ways before crossing it.” Just because things ought to be some way doesn’t mean that they always are.

A special variant of this fallacy is to assume that just because something is legislated, because it’s legal, it’s moral. Slavery, for example, was legal in what today is Canada until 1833. That doesn’t mean that slavery is morally right, although that was the law and perhaps even the sentiment at that time.

In any case, Hume’s Law is a simple and elegant tool to verify that our arguments, or those of others, actually entail our moral conclusions. We can use this rule to revise, correct, expand, or even discard our thoughts, irrespective of our worldview.

Adopt Hume’s Moral Definition, Break Hume’s Law

We have studied the definitions, and we have seen examples. We could call it an episode! But there’s one more thing I want to discuss, and that is what happens when societies change their moral standards and in the process break Hume’s Law.

Let’s start with an example. In countries founded on a Christian moral standard, with corresponding laws, sexual intimacy and cohabitation were considered inseparable from marriage. Partly as a way to assert this, laws would favour married couples in a number of ways, such as spousal support protections, property rights, estates, and the ability to decide about the spouse’s health care in certain conditions, among others. As society’s moral standards changed, marriage was redefined – deconstructed, if you will. Sexual intimacy and cohabitation were decoupled from marriage and became more common on their own. As this happened, these couples started running more often into situations that were well regulated for married couples, but not for them. Over time, laws have been changed to consider these cases.

There are a few things to note here. First, the trigger of this process is a change in moral standards. I’m not saying anyone goes, “This is wrong, but I’ll do it anyway.” More likely I think they go, “There really is nothing wrong with this. We need to change our stance on this. We should be able to do it without judgement, remorse or legal consequences.” Second, it’s not a matter of majority. In fact, it is important that law caters properly to minorities. However, with many of these changes there is a tipping point when the majority comes to accept or approve the new moral standard, even if most of them aren’t personally affected by the change.

Third, one can argue that laws are meant to capture morality. That the objective of laws is to encode what’s right and what’s wrong, or what’s the right way to do things. Therefore, out of an abundance of cases, or out of a majority of citizens tolerating and accepting a minority of cases, laws change to reflect the new moral standard. Finally, because of the moralistic fallacy, there will be a few members of society who will accept, defend or promote the new moral law simply because it is now legal. If this is allowed, if this is right, if this ought to be – then let it be.

It’s an interesting irony: following Hume’s definition of morality almost inevitably results in breaking Hume’s Law. Earlier I said that for Hume, reason wasn’t the source of morality. Reason doesn’t drive morals. And actually, I agree with that: reason alone can’t tell us what’s right and what’s wrong. This is also consistent with Hume’s own law: we shouldn’t extrapolate moral laws from empirical observations.

But Hume’s complete argument on morality is that emotion, passions, sentiment, drive morality. When society takes up this definition of morality, its moral standards change with the times; and after a while, laws must change in consequence. Some of these changes are supported by somewhat logical or reasonable arguments. One can argue that it’s fine to extend people spousal support protections in common law relationships to prevent abuse. But often things get to a point where people just say, “We must get with the times! We need to be on the right side of history! That needs to happen because it’s 2021!” In other words – it is. It ought to be. And the naturalistic fallacy then engenders the moralistic fallacy: “It’s the law. It’s a closed topic, a done deal. Society has moved on from this.”

I find this unidimensional, purportedly linear concept of progress troubling. I find it frail and dangerous. To be clear, I don’t object to the process. This is the hallmark of democracy. If a majority of people share an opinion, it is good and appropriate to follow the democratic process, leverage our institutions and change the law accordingly. Sometimes a minority will do this out of principle or conviction, and that’s something I’ll touch in an upcoming episode.

I’m not objecting the democratic process, where the majority shifts the state of the laws as a result of a change in the moral standards. My concern remains with the way we choose our morals. We can have a carefully argued and selected set of fixed morals, such as a Constitution interpreted in the spirit the original writers meant. Or we can have a shifting standard based on the sentiment of the moment. And I think if we choose the latter, we will make more mistakes. It’s inevitable. I can’t help wondering what will be the 21st century equivalent of legalizing slavery. On what will future generations look back on us with scorn and shame?

Let’s look at one last example. On October 17 2018, Canada became the second country in the world, after Uruguay, to legalize cannabis. The federal government’s reasons to do this were: to dismantle the black market, which is estimated to pour 7 billion dollars into organized crime every year; to keep cannabis out of underage youth’s hands; and to protect the health of cannabis users by regulating the product’s quality.

Those were the overt reasons. And you could say that there also was an argument to be made against the excessively negative consequences of criminal prosecutions from possessing and using cannabis, particularly in racialized communities. However, underpinning all of this was a Hume Law violation: “people will use cannabis no matter what we do. Might as well legalize it.” So much so that other jurisdictions actually expect a windfall from taxation and income from legalizing cannabis. Thankfully, that wasn’t a prominent theme for the Liberal government, because the jury is still out on how effective has legalization been on its goals, which makes the underpinning fallacies especially troublesome. The more logical arguments didn’t quite play out, but the naturalistic and the moralistic fallacies remain strong.

I can’t imagine our standards ever changing enough for us to say one day, “No matter what we do, people will scam other people. Might as well decriminalize it.” “No matter what we do, people will drive under the influence. Might as well decriminalize it.” I don’t think we’ll get to that, but we already have a couple of variants of what I would consider decriminalized murder, and the arguments there aren’t much better than these naturalistic fallacies. Ignorant that I am, I wonder when and how it all ends.

In the meantime, despite all his controversies and errors, Hume has left us his law. And if nothing else, on a smaller scale it remains valuable to help us improve our arguments and have better conversations around us. I hope you find that useful.

Published: February 8, 2021