(Context: My assumption was that to truly know if A causes B e.g. if some government intervention causes growth, I have to actually do the intervention. Merely pointing out the observation that A is covariant with B is not sufficient, since there may be any number of hidden interactions. The idea that Instrumental Variables prove(?) causality through mere observation tripped me the f*ck out, and this is an extremely trippy essay processing that idea)
Our first taste of power comes invariably when, as children, we topple our first stack of blocks
We giggle as we watch it fall, our intent made to action made to outcome
Our first taste of power is our first taste of causality, the great chain of cause-and-effect which we pull upon, and through which our thoughts touch the world
Our power shrinks when we first learn of the primitive tribes, who in fierce drought dance to pray for rain
What foolishness, we are taught to think, for how could mere mortals could move the heavens?
No, the scientists say, if the rain falls after the dance, it is merely coincidence. And if the rain does not fall, that is proof of the dance's wrongness
Chastened, we retreat. We learn correlation is not causation
But, the scientists promise, we may still have a taste of our former power. They offer, in observation's place, the gift of experiment
Consider two identical things, and act upon one but not the other
Whatever change we observe we must be attributed to the action, and thus by clever alchemy, we transmute mere observation into irrefutable truth, a solid gold link in the causal chain
But, the novice alchemist asks, is it not the case that no two things are identical? If two things are identical in appearance, they might be different in substance. If two things are identical in substance, they might be different in space and time
For it remains an unbending constant of the universe; That no two things can be in the same place, at the same time
The journeyman alchemist gestures to the scientists; It is true that no two things are identical in space, time, and form. But the laws of physics and reality apply similarly to similar things
Perhaps our bauxite ore is contaminated with iron or silicon, and without testing the ore we do not know how much it is contaminated with which
But we know that all bauxite ore previously tested have certain individual quantities of contaminants;
If from these individual quantities we take the average quantities of contaminants, and assume that our bauxite ore is the same as all bauxite ores that came before,
Do we not have the best possible prediction of what quantities of contaminants are in our untested ore?
And if we smelt a large quantity of untested ore, then by summing their average quantities of contaminants, do we not have an accurate causal estimate of the purity of aluminium produced?
But, the journeyman alchemist asks, with a glint in their eye; How do we know what we have not tested is the same as what we have?
The journeyman alchemist, secretly a gambling addict, grins as they slip a pair of dice from their sleeve
The beauty of dice, the journeyman alchemist says, is that it is dissimilar to everything, including itself; Thus it is inert, and sampling with this divine alembic does not alter the nature of the thing being sampled; There is no selection bias
So long as we have sampled the bauxite ore we have not tested from the same places as the bauxite ore we have tested, we can be certain that they are identical in their average characteristics
The novice alchemist's brows crease in disagreement -
The laws of physics and reality, the novice alchemist proclaims, does not apply to groups of things but to things themselves
To squint our eyes and blur together fish and whale is foolishness; Grant that we might be able to predict how well a fish-whale can swim, but we would not be able to predict how well a fish-whale would fit on a charcoal grill
However many characteristics we test and find similarity, we will remain uncertain of the similarity of untested characteristics
Nor would we be able to add these pig iron links to the great chain of causality; They might suffice as specialised tools attached to the chain for particular purposes, but they will tear under the whole weight of the chain
What would you propose then?, the journeyman alchemist asks, their fingers steepled in front of their face, which wore an indiscernible expression
The novice alchemist is stumped; They have spent much time thinking about the problems of their field, but little thinking about the solutions
I want to be a scientist, the novice alchemist finally admits. I know that God does not play dice. This uncertainty we have called probability; I want to banish it to the same place we have banished the rain gods
If nothing makes sense and all our alchemical knowledge is self-contradictory, it must only be because we have grouped together different things and called them by the same name
To obtain the purest possible truth, I must start from the smallest possible groups of nearly identical things, obtaining these groups by precise experiment instead of vague observation
The novice alchemist beams with pride at their perfect solution, then their face falls with an awful realisation
Ah, I will never be able to afford all these experiments! The novice alchemist, still prone to fits of youthful melancholy, wonders aloud; But if I can't experiment, then I do not know. And if I do not know, then am I not doomed to complete ignorance?
An angry-looking man, teeth covered in grist, bursts onto the scene
Who ever taught you that all observation is anecdote and that all correlation is not causation?
When you had your first taste of power, toppling your first stack of blocks, did you not observe your intent to swing your hand, nor observe your swinging hand, nor observe the falling blocks that were struck?
Was not the mistake of the primitive tribes that they failed to observe rain only sometimes falling every time they danced for rain?
What matters is not the fact that through experiment you contrive two nearly identical things, but the observation that they are nearly identical
It is true that observation tends to be imprecise, but sometimes there happens a fortuitous natural experiment, which allows us to compare the effects of an action upon two nearly identical things
And if nature does not deign us the convenience of acting directly upon our outcome of interest, we may still determine its effect on an intermediate action, and through the great chain of causality determine the effect of the intermediate action on our outcome of interest
The novice alchemist decries the angry man; Lipstick on a pig! Add the small amount of knowledge we have from controlled experiments to the small amount of knowledge from natural experiments; Add even the uncertain and vague knowledge from statistical alchemy
Do we not still know barely anything? The world is fundamentally unknowable!
The novice alchemist lets out their frustration in a great shout, stunning their teachers into silence
Yet, their false preconception that the world should be knowable having been broken, everything now falls into place
The world is fundamentally unknowable, yet the scientists have turned fire in a boiler to light from a lamp. The world is fundamentally unknowable, yet the scientists can predict the movement of the stars
The world is fundamentally unknowable, but it was possible to learn
Nor had the scientists' tools always been precise, but became more so through gradual improvement; And with the reciprocal improvement of their tools and knowledge, came the obsolesce and death of old knowledge
The alchemists who pursued truth were mistaken; Their methods would lead nowhere; There was no universal truth of a group of things, only temporarily useful generalisations about specific times and places
But what was wrong with studying temporarily useful generalisations? The early scientists' knowledge about the stars did not last forever
Rather the vainglorious pursuit of abstract truth, that impossible philosopher's stone, was not the purpose of knowledge to do useful things?
What useful things do I want to do?, the novice alchemists asks themselves
Only they can answer