This is a historical post.
In my last post, I discussed Scientific Realism vs. Positivism. The conclusion I drew was that, while both are useful points of view, Scientific Realism is the one you want if your desire is to comprehend reality. In this post, I’m going to discuss Deutsch’s arguments surrounding Reductionism and Holism, two points of view that Deutsch argues are also a hindrance to Scientific Realism.
Deutsch describes Reductionism as the belief that:
…science allegedly explains things reductively – by analysing them into components. For example, the resistance of a wall to being penetrated or knocked down is explained by regarding the wall as a vast aggregation of interacting molecules. The properties of those molecules are themselves explained in terms of their constituent atoms, and the interactions of these atoms with one another, and so on down to the smallest particles and most basic forces. Reductionists think that all scientific explanations, and perhaps all sufficiently deep explanations of any kind, take this form. (The Fabric of Reality, p. 19)
The end result of this point of view is a hierarchy of theories similar to this picture I’m taking from the Eternal Universe. (Love that site.)
Deutsch is not denying that you can reduce explanations into a hierarchy like this. That is certainly true. What he is denying is that the base of the hierarchy is somehow more fundamental or more important than another parts of the hierarchy.
Deutsch points out that the Reductionist framework is more “a matter of principle only.”
No one expects actually to deduce many principles of biology, psychology or politics from those of physics. The reason why higher-level subjects can be studied at all is that under special circumstances the stupendously complex behavior of vast numbers of particles resolves itself into a measure of simplicity and comprehensibility. This is called emergence: high-level simplicity ‘emerges’ from low-level complexity. High-level phenomena about which there are comprehensible facts that are not simply deducible from lower-level theories are called emergent phenomena. (The Fabric of Reality, p. 20-21)
Deutsch takes the example above of the strength of a wall as an example of emergence.
For example, a wall might be strong because its builders feared that their enemies might try to force their way through it. This is a high-level explanation of the wall’s strength, not deducible from (though not incompatible with) the low-level explanation… The purpose of high-level sciences is to enable us to understand emergent phenomena…” (The Fabric of Reality, p. 21) 
So Deutsch’s objection to Reductionism isn’t that things can’t be reduced – they can – but rather that a science of particle physics is not necessarily more fundamental to understanding reality than (according to Deutsch) emergent theories such as life, thought, and computation. (The Fabric of Reality, p. 21) Those phenomena are not hopeless derivative of particle physics after all, they are fundamental parts of a potential “Theory of Everything” by which reality is to be understood. 
All of this would seem to indicate that the views of Holism – the idea that all is one and you can’t break the world into parts – might be true instead of Reductionism.
It is not uncommon for scientists that I’ve read to claim that the West believed in Reductionism and the East in Holism. This point of view espouses that the West went about breaking things down into categories and eventually discovered Atomism which in turn led to the West’s powerful scientific knowledge. Meanwhile, the poor East was seeking knowledge through meditation and Holism and thus failed to develop the scientific method.
However (or so goes this viewpoint) it turns out that Holism was true after all. The East wasn’t wrong, they were just premature. Science is now realizing that you can’t understand things one part at a time because you must understand them as a whole. Zen Buddhism was therefore supposedly right after all.
Just as it’s true that we can reduce scientific theories to lower level theories, it’s also true that the very act of categorizing things and reducing them fails to fully grasp the whole. Douglas Hofstadter (author of the Pulitzer prize winning Gödel, Escher, Bach: An Eternal Golden Braid) is a student of Zen Buddhism (to a degree) and sees real value to Holism. He attempts to define the goal of enlightenment in Zen Buddhism as transcending what he calls “dualism” which he defines similarly to what we are calling Reductionism. 
Now what is dualism? Dualism is the conceptual division of the world into categories. …breaking… the world into categories takes place far below the upper strata of thought… In other words, human perception is by nature a dualistic phenomenon – which makes the quest for enlightenment an uphill struggle, to say the least. (Gödel, Escher, Bach, p. 251)
Just as reductionism has truth to it, but isn’t the truth, the same could be said of Holism as well. Deutsch argues that the problem with Holism is that it’s the reverse – but effectively worse – error of Reductionism. It favors emergent explanations over reducible explanations. Deutsch responds, “Where whole sciences are reducible to lower-level sciences, it is just as incumbent upon us as scientists to find those reductions as it is to discover any other knowledge.” (The Fabric of Reality, p. 21)
If neither Reductionism nor Holism is fully correct, does this imply that all scientific explanations are created equal? Deutsch, argues no. His point of view is that there are privileged scientific theories, so to speak.
The laws of biology, say, are high-level, emergent consequences of the laws of physics. But logically, some of the laws of physics are then ‘emergent’ consequences of the laws of biology. It could even be that, between them, the laws governing biological and other emergent phenomena would entirely determine the laws of fundamental physics. … The truly privileged theories are not the ones referring to any particular scale of size or complexity… but the ones that contain the deepest explanations. …What makes a theory more fundamental, and less derivative, is not its closeness to the supposed predictive base of physics, but its closeness to our deepest explanatory theories. (The Fabric of Reality, p. 28)
I believe that Deutsch is onto something here. In particular, I agree with him that the emergent explanations of thought, life, and computation are fundamental to understanding the nature of reality. 
- Using Deutsch’s criteria of what makes the deepest theory, what are our deepest theories?
- How many of you have practiced meditation? Have you ever reached a state where you lost your sense of self?
- Using the example of an explanation for why a wall is strong, could the following explanation be reduced to an algorithm?: “Because its builders feared that their enemies might try to force their way through it.”
 In a past post, I asked the question of how does one explain spirits and Agellius (A Catholic Blogger) responded that the explanation of spirits is that they are disembodied minds, and therefore he did have an explanation of spirits without having to come up with a reducible explanation of, say, how spirits can store memories. Agellius was confusing levels of explanation. My question was limited to reducibility so Agellius was only restating what I had already said – that he had no reducible explanation for how spirits can be intelligent and therefore the whole phenomena was not further explainable and comprehensible from within his worldview. Agellius, as a Catholic, does not expect there to be an explanation as to what spirits are beyond an emergent definition of what they are at an abstract level.
Personally, I find this non-reducible point of view questionable because brains have reducible explanations – namely the activity of brain cells. So the one objective example of minds that we know of does have a reducible explanation. Therefore I find it curious Agellius’ assumption that by definition a spirit (as an explanation) lacks reducibility. If they did, why would brains need reducibility? This would imply that brains could have been non-reducible structures, just like spirits, but God decided to make brains reducible even though it drastically misleads us about the true nature of reality. I prefer that more straightforward explanation that brains teach us something universal about minds: that all minds are complex emergent phenomena that are interactions of simpler entities.
 Theory of Everything. I am here using the term as Deutsch uses it rather than in the more usual way of referring to some ‘fundamental’ physics theory that is yet to be found that explains quantum gravity. Deutsch gives the following explanation:
A reductionist thinks that science is about analysing things into components. An instrumentalist thinks that it is about predicting things. To either of them, the existence of high-level sciences is merely a matter of convenience. Complexity prevents us from using fundamental physics to make high-level predictions, so instead we guess what those productions would be if we could make them – emergence gives us a chance of doing that successfully – and supposedly that is what the higher-level sciences are about. Thus to reductionists and instrumentalists, who disregard both the real structure and the real purpose of scientific knowledge, the base of the predictive hierarchy of physics is by definition the ‘theory of everything’. [Used in the conventional sense.] But to everyone else scientific knowledge consists of explanations, and the structure of scientific explanation does not reflect the reductionists hierarchy. (The Fabric of Reality, p. 22)
 Dualism. Hofstadter uses the word ‘dualism’ differently than the traditional Christian point of view which generally refers to
…a philosophical viewpoint espoused by Rene Descartes, and it asserts that there are two separate kinds of substance: ‘mind-stuff’ and ordinary matter. Whether, or how, one of these kinds of substance might or might not be able to affect the other is an additional question. The point is that the mind-stuff is not supposed to be composed of matter, and is able to exist independently of it. (Roger Penrose in The Emperor’s New Mind, p. 21).
The traditional Cartesian variety of dualism – where there is no connection between matter and mind — is almost certainly wrong. But as it turns out, there is a sense in which dualism is true to a degree. Materialist John Searle attempted to argue against dualism and, in my opinion, accidently points out that it follows inevitably from computational theory. See John Searle’s article “Minds, Brains, and Programs” (I found it in The Mind’s I, p. 372) for further discussion. I will address this further in future posts.
 I confess, I was a Computer Science major. No wonder I’m drawn to the point of view that computational theory is fundamental to reality.