Are Cause and Effect an Illusion? A Dialogue Between Hume and Quantum Mechanics

This may be sudden, but please try tapping something hard with your fingernail.

You will hear a "clink" sound, and we intuitively perceive this sequence of phenomena as an absolute causality: "I tapped something hard"(cause)→ "a clink sound occurred"(effect).

Now, let us ask here.

Does thisnecessity that "a cause produces an effect," which we believe in without doubt,actually hold true?

🔳 "Causality" is a "habit of the mind," not reason

The 18th-century Scottish philosopher David Hume presented a fundamental skepticism toward causal relationships inA Treatise of Human Nature (1739) andAn Enquiry Concerning Human Understanding (1748).

"Do we really see 'causality'?"

According to Hume, the sequence of phenomena at the beginning where you tapped and a sound occurred simply means that theevents of "tapping" and "a clink sound occurring" just exist.

For example, suppose billiard ball A hits ball B, and B moves. We see this and think "A moved B," but according to Hume, what we are actually seeing is just a succession of two events: "A moves" and "immediately after, B moves." There is nocause producing an effectandno necessary connection is observed anywhere.

You might think, "That's impossible!"

but this cannot be disproven even with modern science. (It cannot be proven either.)

Scientific laws (such as Newtonian mechanics or thermodynamics) are all based on observed regularities.
In other words, they depend oninductive reasoning, which Hume criticized. The justification for induction lies outside of science.
Science assumes that "the sun will rise tomorrow," but that assumption itselfcannot be proven by science.
Induction presupposes causality, which is"because it worked until now, it will work in the future as well".

We form a certainhabitfromrepeated experiences, such as that it is hot when we get close to fire or that glass breaks when we throw a stone.
This habit makes us convinced thatit will happen the same way next time.

However, Hume says this is not logic, but merely apsychological tendency.

In other words,the essential necessity of causality itself cannot be observed.

For Hume, the world is not "A produces B," but merely abundle of successive impressions where "B follows A".

This is a bit of a tangent, but in Hikaru Utada's song “Nanairo demo nai Hana” (A Flower of No Color), there is a lyric that goes,

I interpret the part “because I promised someone” as referring to Hume's “formation of psychological habits” through repetition. This “psychological habit” is what
“promises us” the conviction that “the sun will rise tomorrow too.” The

“renowned scholar” refers to Hume, and the part “we are apparently illusions” seems to correspond to Hume's idea that humans are bundles of perceptions.

Utada-san has read books by Bergson and Lacan, and anyone who reads Bergson and Lacan has undoubtedly read Hume as well.

Utada-san's songs contain very deep philosophy within simple expressions.

🔳 Hume and Quantum Theory—Resonance in the Collapse of Causality

This argument of Hume's quietly severs the roots of modern rationalism. And this skepticism resonates in an unexpected place in the modern era.

That is quantum mechanics.

At the beginning of the 20th century, physics hit the limits of classical determinism. The motion of electrons could no longer be described by Newtonian mechanics (even with the theory of relativity), and as

Heisenberg demonstrated, it is governed by the uncertainty principle, which states that the position and momentum of a particle cannot be determined simultaneously. The world is no longer a linear chain of causality where doing this necessarily leads to that, but rather something that fluctuates within a web of probability and observation.

For example, it is impossible to predict when a radioactive atom will decay. One can only say that, on average, it will decay within a certain amount of time based on probability. At the moment of that decay,
asking what the cause is, is itself meaningless. Here, we must listen to Hume's voice once again.

“We only see the succession of events.”

In the quantum world, the law of causality is no longer an absolute rule, but merely a temporary structure established within the relationship between observation and events. Just as Hume says,

causality is nothing more than an illusion projected by our minds onto nature.

The physicist Niels Bohr also stated that nature is not determined until it is observed, emphasizing that physical laws themselves depend on their relationship with observation.

This can also be read as modern science proving the illusion of causality in the Humean sense.

When Hume attempted to dismantle the myth of causality about 270 years ago, it was merely a quiet question within philosophy.
However, I find it astonishing that modern physics has rediscovered that question in the very structure of nature itself.

The illusions of the human mind resonate endlessly with the fundamental behavior of the real world.

As Bergson says, is the present we live in not something that manifests at the intersection where the vital tendency (philosophy) as constant duration and the material tendency (science) meet? phenomenon.

In Hume's time, no one could have imagined that nature would return an answer in this form.

But now, the necessity of causality wavers like mist, and we are forced to ask again.

Does the order of this world really exist there? Or is it just that we see it that way?

That is the question.

Finally, Niels Bohr, one of the founders of quantum mechanics, says:

"Science is not a means to find truth,

but a way to reduce illusions."

Thank you for reading until the end.

See you again.