The idea that we live in a ‘causal’ universe seems to be widely accepted and sits well with the model of Newtonian Physics. However, the idea is ill defined, seems to rule out free will, is at odds with many other aspects of contemporary physics and is not so useful in complex multifactorial systems such as we find in biology.
“Causality is influence by which one event, process, state, or object (a cause) contributes to the production of another event, process, state, or object (an effect) where the cause is partly responsible for the effect, and the effect is partly dependent on the cause. ” – Wikipedia
This may sound straightforward but all that has really happened is that the word causality has been replaced by a sentence including words such as influence, contributes, responsible, production and dependent.
The concept relies heavily upon the idea of an event as being a separate identifiable unit of the physical universe whereas in actuality the whole of reality progresses as a single unified whole. Moreover what is ‘influence’ if not a synonym for ‘causality’ which is the very word we are trying to define?
Again from Wikipedia: “Causality is an abstraction that indicates how the world progresses. As such a basic concept, it is more apt as an explanation of other concepts of progression than as something to be explained by others more basic. For this reason, a leap of intuition may be needed to grasp it.” Excellent. Causality is an abstract concept that is neither defined nor required in science.
Erwin Schrödinger writes in his book What is Life? that “Physical laws rest on atomic statistics and are therefore only approximate“. Atoms are in a continual state of random vibration (Brownian motion) and so it is not possible for any meaningful relationships between them to be formulated as a physical law and order can therefore only arise from the statistical behaviour of a large number of atoms.
“All the physical laws that are know to play an important part in the life of organisms are of this statistical kind; any other kind of lawfulness or orderliness is made inoperative by the increasing heat motion of the atoms.”
Schrödinger was instrumental in the formulation of Quantum Mechanics which is said to provide the most accurate description of physical reality that we have. However, it is rooted in the idea that matter consists of many alternative potentialities in the form of superimposed waves, one of which is selected purely at random to participate in reality and interact with the rest of the universe.
Quantum physicists declare that “The universe is quantum” thereby asserting that randomness is foundational to reality and all else is just the most likely outcome of many random events as explained by Schrödinger himself.
Where is the place here for causality?
Statistical causality. The Galton Board gives some indication of how order can arise from chaos. Each individual ball follows a path determined by independent random events but the ensemble always produces a bell curve.
The curve is slightly different each time and the differences are not predictable but the overall approximate shape is predictable and is the same each time owing to the ‘laws’ of statistics. Note that these laws now are purely mathematical and do not even depend upon the laws of physics, indeed, according to Schrödinger they are at the very roots of physics.
The Galton board is similar to the situation in biological systems whereby a noisy environment causes completely random Brownian motion that is unpredictable at the atomic level but somehow gives rise to a highly ordered and functional cellular structure.
Does this qualify as ‘causality’? Not how most people would think of it.
Newtonian causal systems are divergent in the sense that a small inaccuracy in hitting a billiard ball, say, can lead to multiple possible outcomes of increasing difference, but statistical causality such as described above, are convergent in that they will inevitably reach the same outcome, via an infinite number of possible paths – differences decrease in this case.
This is why Schrödinger claims that life forms are the size that they are. Atoms themselves are too unstable to form coherent life at the atomic scale – you need enough of them to be able to form a large scale statistical system before self-organisation is feasible.
Statistical convergence can be described as goal-oriented behaviour or a final cause. The motions of the individual elements are random and therefore cannot be described as causal but since the outcome is guaranteed it seems as if order and organisation proceed from the outcome itself i.e. the outcome is the cause of the preceding activity.
“The final cause of a change or movement. This is a change or movement for the sake of a thing to be what it is. For a seed, it might be an adult plant; for a sailboat, it might be sailing; for a ball at the top of a ramp, it might be coming to rest at the bottom.” – Wikipedia
Aristotle 384–322 BC described four distinct types of cause and Wikipedia asks “What are the causes of a table?”
- Material cause – the wood itself
- Formal cause – the design of the table
- Efficient cause – the work of the carpenter
- Final cause – the purpose of the table (dining)
The idea of a final cause seems to have fallen out of fashion in science but is still present in the everyday thinking and language of even scientists themselves. Consider: “Giraffes evolved long necks in order to reach high branches” or: “Inflammation is the body trying to achieve homeostasis”.
Many commentators have said that in fact the idea of a final cause is actually essential for an understanding of biology at all levels from gene expression and cell division at the molecular level, to blood pressure regulation at the organ level, to psychological goals at the behavioural level and to the need for adaptation at the evolutionary level.
Consider D’Arcy Wentworth Thompson’s dismay at Darwinian explanations for the evolution of species: “We have reached a teleology without a télos, an adaptation without design, a teleology in which the final cause becomes little more, if anything, than a mere expression or resultant of a sifting out of the good from the bad, or of the better from the worse, in short of a process of mechanism.” – On Growth and Form (1917)
Causality in everyday language. If I light a fuse on an old cannon the heat will cause ignition of the gunpowder, causing an explosion which in turn will cause the the ball to be ejected from the cannon whereupon friction with the air will cause the ball to slow down and gravity will cause it to fall to the ground.
This is all fine and is typical of the way language is used in practice. But if we try to formalise the idea of causation here we are in trouble as all I have done is to describe what is happening and add in the word ’cause’ every so often. There are a multitude of different mechanisms at work here and so a multitude of different ’causes’. I have used the word ’cause’ to apply to seemingly unrelated phenomena.
There is an infinite variety of events happening in reality and so a potentially infinite variety of causes. So if we really want to use the idea of causality we must try to find a way of deciding which of those we want to describe as ‘causal’ or else the word is just meaningless. We need to find some common feature of all the different causes.
In classical mechanics the common factor is usually the intuitive but nevertheless abstract concept of ‘energy’ which is said to be conserved but is transmuted from one form to another to effect physical change. So for example, electrical energy may be converted to kinetic energy within an electric motor in order to cause movement.
Model specific causality. Why does an apple fall to the ground? Science gives several explanations:
- It is pulled down by gravity (Newtonian physics)
- It follows the curve of space-time (Relativity)
- Potential energy is converted to kinetic energy (Lagrangian mechanics)
So we have three different theoretical models of reality giving three very different versions of causality for this specific example.
Most importantly, these scientific frameworks do not in any way attempt to prove causality but rather serve as definitions of causality. Each model gives a precise mechanism for describing the behaviour of the apple that can be quantified and tested in an experimental setting to give credence to the model.
This seems to be the only sensible way forward if we really want to define causality in a formal manner. It is defined by a specific mechanism which itself lies within a specific theoretical framework.
Do we even need to do this though? Can we not just say that an apple will behave a certain way in a gravitational field? Where is the need to use the word ’cause’ here?
Causality is relative to point of view. The case of The Barnsley Fern is clearly a matter of final causation if all we see is the outward physical form but once the generation mechanism is known, statistical causation expressed via a template seems the more appropriate and more fundamental source of the organisation.
Causality in General Relativity. The theory of relativity boils down to a bunch of equations describing structured interactions between mass, space and time. ‘Fields’ exist within all space which is represented as a continuum. The idea of an event does not sit well within this framework and hence the notion of causality as normally thought of is not supported.
” Strictly speaking, the notion of an event is an idealization, in the sense that it specifies a definite time and place, whereas any actual event is bound to have a finite extent, both in time and in space.” – Wikipedia
Having said this, Wikipedia goes on to talk about events as though everything is fine, but because it is relativity, things get a bit odd. “In both Einstein’s theory of special and general relativity, causality means that an effect cannot occur from a cause that is not in the back (past) light cone of that event.” – Wikipedia
The complication comes from the fact that the intuitive notion of causality includes the idea that cause always precedes effect. However, within the framework of relativity there is no universal time, clocks run at different rates in separate locations and the notion that events happen in a strict time order is just not supported.
There is a concept of causality here but it is very specific to the theory and far from intuitive.
Correlation is not causation and we all know about that but as the video of the double pendulum shows, causation does not necessarily lead to correlation either. We can clearly see a mechanical connection between the two levers which we interpret as causation but if we didn’t know about that then how would we determine causality?
The philosophers want to somehow define causality as being independent of the mechanism, independent of a theoretical framework. But how to do this? What do you have if not an observed (or theoretical) mechanism?
We are left with correlation and time ordering. However, time ordering is complicated in Relativity and the Stanford Encyclopedia of Philosophy even wants to allow for backward causation , so eliminating the need for cause to precede effect!
Multi-scale causality. Here we see a stream whose water flows in a particular pattern and is said to be composed of many water molecules interacting with each other. One view is that the flow of water can be explained by the interaction of such molecules and that therefore causation is from bottom up reductionism).
This is not how physicists calculate the flow of water in a pipe however. Instead they will use the Navier-Stokes equations which treat water as a continuously flowing medium with properties not present in individual water molecules such as density, viscosity, pressure and temperature.
There is no mention of molecules in these equations and the fact the equations treat water as a continuum means that it is actually impossible to describe them in terms of molecular movement.
The characteristics of the water flow are determined by the shape of the river bank, thereby implying top-down causation as opposed to bottom up. Each individual water molecule is pushed around by its neighbours whilst at the same time continuing to obey the laws of physics by maintaining electron orbits etc.
This happens everywhere in physics and biology that the laws are different at each physical scale of reality and only loosely related to each other. In the world of physics then, causation tends to confine itself to a particular scale of reality whether it be planetary, human, cellular or molecular. The strong nuclear force is simply not relevant to the motions of the planets.
Biology is different, with organised networks devoted to conducting information (causality) from the macro down to the micro and back up again, with sensory processing, gene expression etc. This could be said to be one of the major defining properties of living systems.
Complexity, causation and ‘agency’. In one experiment, bacteria with a defective lac-z gene were exposed to lactose and immediately went to work constructing a viable genome and then expressing it to make the correct proteins for digesting lactose. The fluid genome.
Does this count as causation?
We see this all through biology that a complex effect can result from a simple cause but is it really a useful way to think about this, that a simple molecule can cause a complex sequence of meaningful goal-oriented events culminating in a beneficial modification to a functioning organism?
Is it not better to regard the bacteria as an intelligent adaptive system capable of interpreting external inputs and itself initiating the relevant genetic modification and expression in order to achieve it’s aims?
Intelligence, agency, adaptation, interpretation seem concepts more appropriate for the development of an understanding of the problem. If the object being affected has more degrees of freedom than the cause itself, if it has a choice over which effect to manifest then the idea of ’cause’ isn’t particularly useful. From this point of view, the more complex system is the causal agent, making it’s own ‘decisions’ from multiplexed input.
David Bohm’s view was that everything we see lies in the domain of the Explicate Order which is the visible expression of events within the Implicate Order and that any causality we see is likely an illusion constructed by our senses and that any scientific endeavour is constrained by the limitations of measurement techniques. David Bohm
From Bohm’s perspective even the movement of an object through space may be an illusion. He asks us to imagine that it may be a series of almost instantaneous manifestations of similar looking wave forms which appear at slightly different places as time progresses, thereby giving the illusion of movement.
Intense discussions amongst scientists as to which scientific models are valid and which delineate true or real causes are now seen to be mere vanity as all we ever see is the surface of a greater dimensional unfolding of a universal pattern, the large part of which is hidden from us. We see waves in the sand, formulate laws to describe them and then imagine we have discovered ‘causality’.
“I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.” – Isaac Newton
- Causality is a useful concept for functioning in everyday life
- The idea of causality within a specific theoretic model is sound but not strictly necessary.
- Philosophical notions of absolute causality (mechanism agnostic) are pure pipe dreams.
- Biology seems to run on statistical causality (structured randomness).
Backward causation – Stanford Encyclopedia of Philosophy
A theory of biological relativity: no privileged level of causation – Denis Noble
Regulation of newly evolved enzymes. I. Selection of a novel lactase regulated by lactose in Escherichia coli – PMID: 4598756 – B.G. Hall, D.L. Hartl
Goal directed activity in life – E S Russell
On Form and Growth – D’Arcy Wentworth Thompson