6/18/2022
Hume’s Fork
“All the objects of human reason or enquiry may naturally be divided into two kinds, to wit, relations of ideas, and matters of fact. Of the first kind are the sciences of Geometry, Algebra, and Arithmetic…[which are] discoverable by the mere operation of thought … Matters of fact, which are the second object of human reason, are not ascertained in the same manner; nor is our evidence of their truth, however great, of a like nature with the foregoing.
Hume, David. An Enquiry Concerning Human Understanding
And with this quote, a fork is made. Scottish philosopher David Hume (1711–1776) says there are only two types of statements, relations of ideas and matters of fact.
Relations of ideas are analytic, a priori, necessary statements. Analytic means that the predicate of any subject is already contained within the subject. For instance:
- Frozen water is ice.
- Bachelors are unmarried men.
- Two halves make up a whole.
- All water is wet.
These are what you might call “No shit!” statements. They’re redundant statements where clarification relies on the definition of the subject.
A priori means knowledge prior to any experience. The justification for the validity of the statement requires no empirical proof to verify.
Ultimately, all analytic statements are also a priori statements. Also, if an analytic-a priori statement is true, then it is necessarily true, or if it is false, it is necessarily false.
The other prong on Hume’s fork are matters of fact or synthetic a posteriori statements. Synthetic means the predicate is not contained within the subject. For instance:
- Babies wear hats.
- The table in the kitchen is round.
- My computer is on.
These are what you might call the “Aww shit!” statements. The predicates in these sentences cannot be determined just by knowing the subject. It requires additional evidence outside of logic. A posteriori means empirical evidence is necessary to prove a statement true or false. Just like with analytic-a priori statements, all synthetic statements are also a posteriori statements. Whether a baby has a hat on, whether the computer is turned on, and the shape of a table, all require empirical observations to determine their truth-content. Synthetic a posteriori statements are only contingently true or false, not necessary. Sometimes those statements are true; sometimes they’re not.
The analytic-synthetic duality has to do with the logical formula of a statement. It’s grammatical. The apriori-aposteriori duality is based on the methodology you use to acquire knowledge about said statement.
So, what are the consequences of Hume’s profound forking?
Well, if you look at the analytic, a priori statements, honestly, they aren’t very interesting. It’s the “no shit” statements after all. We can feel confident that we know these statements with 100% certainty. Now, you may be thinking, “Hey Zach, how can these statements be a priori when we had to learn about them in the first place, you know, with our eyeballs & our earballs?”
And, to that I will state, “Now, you’re thinking like a philosopher. And, I wish your future job prospects goodbye.”
Unless you’re like a Platonist, you had to learn all these definitions. And before that you had to learn a whole language. This feels a posteriori out the wazoo (pun intended). How can we be certain of the a priority of anything? Put a pin in that for now.
Let’s talk about the “Aww shit!” statements: synthetic, a posteriori statements. These statements offer us something new, something interesting. Synthetic, a posteriori are the only statements which can be considered scientific because the definition of scientific requires empirical measurements. At the same time, we can never be 100% certain about these statements like we can with the “No shit” statements. As we repeatedly observe the truth or falsity content of these instances, we can become increasingly more certain about a statement to the point where it kind of seems like a “No shit!” statement. And this is where we run into the problem of the a priority of anything.
Take the statement, “All water is H2O.” What kind of statement is this?
You might say, well No Shit! It’s a priori, analytic. Because water and H2O are, as a matter of fact, identical. However, for the overwhelming majority of human history, the statement “All water is H2O.” would have been meaningless, as humans did not know about molecular constructs or atomic properties. Okay, well, human’s are fucking stupid; objectively water & H2O are the same now, have been since the dawn of time, and, barring some catastrophic change in the fundamental forces of the universe, will continue to be the same for the foreseeable future. It’s a No Shit! Analytic, a priori statement; end of discussion. We’re 100% certain.
There was a time when “All water is H2O” was an “aww shit!” statement. But, once any statement becomes a “No shit!” statement, it ceases to be scientific, because scientific statements are always based on empirical facts. At the same time, since “No shit!” statements are always necessarily True or False, this creates a problem where science is incapable of getting at the Truth.
Now, the point of his fork that Hume is really trying to drive home is that the overwhelming majority of the statements we consider analytic, a priori are actually synthetic, a posteriori which we have adopted as a priori, not because of some objective eternal content they may appear to have, but instead based merely on habit, custom, and tradition.
Hume would likely consider all of the examples I used previously as synthetic, a posteriori statements. Really, the only statements Hume might consider properly “No shit!” statements are statements like tautologies and mathematical statements. Hume says relations of ideas can only be used to refer or explain other relations of ideas and cannot describe matters of fact. If this is true, than all true “No Shit!” statements cannot explain the world, because only empirical statements can describe the world around us.
It might help to give little historical context on why this is so important to Hume in order to really explicate how influential Hume’s Fork was to the enlightenment. It’s obvious Hume privileges matters of facts over relations of ideas. Hume was an empiricist after all, similar to philosophers John Locke & Bishop Berkeley. Empiricists believed all knowledge could only be attained via the senses. The empiricists were philosophically opposed to the other major philosophical school of thought during the enlightenment: the Rationalists. The rationalists believed only Relations of ideas, more specifically the logical application and manipulation of relations of ideas, could provide true knowledge about anything, as these were the statements which appeared necessarily True or False.
Hume’s profound forking states that if relations of ideas are actually relations of ideas (i.e., analytic, a priori “No Shit!” statements) then they are incapable of describing reality at all. If, on the other hand, these statements are actually “Aww Shit!” statements we’ve gotten bored with through tradition and custom, then the presuppositions of Rationalism are untenable.
Let’s look at probably the most famous Rationalist statement, “I think, therefore, I am.” First off, this is actually two statements, the second of which doesn’t actually explain anything because Being is not a predicate. But, the first one is more important for our purposes anyway. I think. How do I know I think? Well, because I have the experience of thinking. Whenever I think about anything I have some type of experience. For instance, when I think of Ayn Rand, I feel a deep disgust.
Hume doesn’t believe metaphysical statements are “No Shit!” or “Aww shit!” statements, he believes they are bullshit statements. And, not just metaphysical statements; theological too. If Hume is right in his forking, there’s no way of ever proving God exists.
“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, David. An Enquiry Concerning Human Understanding.
This is not the end of the forking. The forking could potentially spell disaster for science and empiricism as well. Hume believes science is on a collision course with itself. But…. That’s for the next video. In our next video, we’ll look at the threat to science Hume’s Forks presents, and one philosopher’s attempt to prevent that threat. In our next video, we’ll learn how to philosophize with a pitchfork.
