The Eureka machine and cliodynamics

Computers are incredibly fast, accurate, and stupid. Human beings are incredibly slow, inaccurate, and brilliant. Together they are powerful beyond imagination. (Einstein)

Michael Schmidt and Hod Lipson have apparently developed an automated search algorithm which discovers physical laws and conservation equations from scratch. The algorithm scrutinises the experimental data extracted from the motion capture of physical systems, and reproduces the classical laws which explain the data. Or, as The Guardian claimed, Schmidt and Lipson have developed a ‘Eureka machine’.

In a technique Schmidt and Lipson refer to as ‘symbolic regression’, their algorithm searches the space of possible mathematical expressions until it finds analytical expressions which reproduce the empirical data. Starting from algebraic operations and simple analytical functions such as sine and cosine, the algorithm randomly re-combines previous equations and parameters, and tests each set of expressions for accuracy against the empirical data, until it reaches a desired level of accuracy. Schmidt and Lipson’s algorithm was able to converge on the Hamiltonians, Lagrangians and force laws of classical physical systems, including non-linear systems.

As an aside, if it is true that civilization is a non-linear classical physical system, then Schmidt and Lipson’s algorithm could perhaps be applied to the data generated by human history, to discover the fundamental laws of cliodynamics. The difficulties of extracting empirical data in this case, where there is only historical documentation rather than motion capture, are obviously not to be underestimated. Moreover, whilst Schmidt and Lipson are able to pre-specify what the state variables of their systems are – they direct their software to look at positions, velocities and accelerations – in the case of cliodynamics, a central difficulty is identifying what the state variables actually are.

Schmidt and Lipson’s work raises a number of funamental issues for both the philosophy of science, and for physics. The fact that their algorithm converges on unique, self-consistent laws, seems to undermine the purported underdetermination of theory by data, a popular bone of contention in the philosophy of science.

It also looks like this work is the first serious step down a road which will considerably alter, and perhaps reduce the creative opportunities for physicists. There would still be, of course, the need to develop such algorithms, to prepare the input data, and to interpret the output. And it should also be emphasised that, from the perspective of mathematical physics, the primary creative task is the discovery of mathematical structures, not the discovery of the laws satisfied by the variables embedded in those structures. An algorithm which discovers the mathematical structures necessary to represent the physical world is a step beyond the work of Schmidt and Lipson. Nevertheless, whilst mathematical physicists might take this consolation, the long-term prospects may not be quite as rosy for their counterparts in theoretical physics.

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Published in: on April 18, 2009 at 11:28 am  Leave a Comment  

Conor Cunningham and Darwinism

Philosopher and theologian, Conor Cunningham, argues that Darwinism is consistent with Christianity. His argument is that the Biblical account of the creation of man in Genesis, is merely allegorical, and that it was traditional amongst the Founding Fathers of the Christian church not to interpret Genesis literally. Augustine, he claims, would not have been perturbed were he to have known about Darwinian evolution.

Cunningham, however, seems to have missed a crucial point. Darwin’s account of the origin of mankind not only refuted the literal Biblical account, it also refutes the belief that God is responsible for the existence of mankind. Evolution by natural selection is not a deterministic process, hence unless one postulates that the universe is deterministic on a lower level than that at which evolutionary biology operates (a postulate which quantum theory renders problematic), the evolution of humanity by natural selection entails that the existence of humanity is a matter of pure chance; the existence of humanity is a contingent property of the universe, something which might not have happened at all.

Hence, Darwinian evolution is inconsistent with the essential Christian belief that God is responsible for the existence of mankind.

Published in: on April 11, 2009 at 11:07 am  Leave a Comment  

Super-nonsense

It’s rational to believe that irrationality is an ineliminable aspect of human mentality. As the consistently superb Paul Broks puts it,

The capacity to hold rational thoughts alongside irrational intuitions is part of the mind’s design. Even if we deny belief in the supernatural – in ghosts, say, or astrology – we are all inclined towards magical thinking and superstition. It’s a frame of mind that one direction opens out to a dream world of myth and imagination and the other leads to practical creativity in the arts and sciences. The dark side is mental illness.

Psychologist Bruce Hood claims in his recent book Supersense, that such irrationality has evolved by natural selection, by virtue of contributing to our survival at some point in the past. This is a viable hypothesis, although, as Michael Brooks points out in his New Scientist review, not necessarily one which is supported by any solid evidence as yet. However, Hood also appears to extrude the following philosophically flimsy argument from this hypothesis:

There are good, scientific reasons why religion won’t disappear…Spiritual thinking is not about being simple-minded or stupid it’s about being human. We are, [Hood] suggests, “a sacred species”…Our supersense gives us sacred values, and our sacred values create taboos. Taboos, in turn, provide a means for group cohesion. “Irrationality makes our beliefs rational because these beliefs hold society together,” Hood says. If hardened sceptics were to accept that irrationality is, well, rational insofar as it serves to hold societies together, that would constitute an important step toward a more tolerant and unified society.

The first error here lies in the conflation of the irrational with the sacred. There are many types of irrationality, some of which are necessary to maintain personal relationships and social cohesion, but which don’t involve the religious type of sacred belief. Socially-cohesive irrationality may well involve holding certain things as sacred in the sense that they are held in great reverence, but without involving the religious notion of the sacred, which explicitly requires belief in the supernatural.

Secondly, the religiously sacred brand of irrationality is demonstrably unnecessary for social cohesion. There are, for example, numerous non-religious, professional or collegiate groups, such as doctors, trades unions, and soldiers, which are not bound together by a shared belief in the sacred or supernatural, but simply by shared interests and experiences. Moreover, the existence of socially cohesive secular European states attests to the socially superfluous nature of religiously sacred belief.

Thirdly, the religiously sacred strain of irrationality is demonstrably insufficient to promote social cohesion. For example, the notoriously religious United States is beset with much higher levels of violence and homicide than secular Europe; that’s hardly a great advert for the socially cohesive power of religion.

Finally, even if it is acknowledged that there are circumstances under which religiously sacred beliefs do promote greater social cohesion, such as that to be found within the Islamic theocracies which spawned Al-Qaeda and Hezbollah, the existence of religiously-driven social cohesion seems to promote a vicious in-group/out-group mentality which leads to inter-group conflict. In this respect, it is perhaps no coincidence that the notoriously religious United States is also the notoriously war-mongering United States.

Published in: on April 3, 2009 at 5:50 pm  Leave a Comment