Hoyle's fallacy

Hoyle's Fallacy, sometimes called the junkyard tornado, is a term for Fred Hoyle's flawed statistical analysis applied to evolutionary origins, in which he compares the probability of cellular life evolving to the chance of a tornado "sweeping through a junkyard" and assembling a functional aeroplane. Similar observations predate Hoyle, and have been found all the way back to Darwin's time.

Hoyle's statement

According to Hoyle's analysis, the probability of cellular life evolving were about one-in-10⁴⁰⁰⁰⁰. He commented:

The chance that higher life forms might have emerged in this way is comparable to the chance that a tornado sweeping through a junkyard might assemble a Boeing 747 from the materials therein.

which is a reflection of his stance reported elsewhere:

Life as we know it is, among other things, dependent on at least 2000 different enzymes. How could the blind forces of the primal sea manage to put together the correct chemical elements to build enzymes?

Details

Hoyle's Fallacy derives from arguments most popular in the 1920s, prior to the modern evolutionary synthesis, which are rejected by evolutionary biologists. A preliminary step is to establish that the phase space containing some biological entity (e.g. humans, working cells, the eye) is enormous — something which is not contentious. Hoyle's Fallacy is to infer from the huge size of the phase space that the probability that evolution yielded the entity is exceedingly low. Sometimes arguments exhibiting Hoyle's Fallacy also invoke Borel's Law, which claims incorrectly that highly improbable events do not occur. (If all possible outcomes of a natural process are highly improbable, then a highly improbable outcome is certain). The true Borel's law is actually the Strong Law of large numbers, but creationists have taken a simple statement made by Borel in books written late in his life concerning probability theory and called this statement Borel's Law. This "Borel's Law" is actually the Universal probability bound, which makes sense mathematically, but when applied to evolution is axiomatically incorrect. The Universal Probability Bound assumes that the event one is trying to measure is completely random, and some use this argument to prove that evolution could not possibly occur, since it's probability would be much less than that of the Universal Probability Bound. This, however, is fallacious, given that evolution is not a completely random effect (Genetic drift), but rather proceeds with the aid of Natural selection

Hoyle's Fallacy is comparable to the older infinite monkey theorem, but applied to cellular biochemistry instead of the works of William Shakespeare. The fallacy claims that the probability that a protein molecule could achieve a functional sequence of amino acids is too low to be realised by chance alone. Hoyle calculated this as being comparable to the probability that a tornado could sweep through a junkyard and randomly assemble a Boeing 747.

The argument conflates the difference between the complexity that arises from living organisms that are able to reproduce themselves (and as such may change to become more complex over time) with the complexity of inanimate objects, unable to pass on any reproductive changes (such as the multitude of parts manufactured in Boeing 747), the comparison breaks down because of this important distinction.

According to Ian Musgrave in Lies, Damned Lies, Statistics, and Probability of Abiogenesis Calculations:

These people, including Fred, have committed one or more of the following errors.

1. They calculate the probability of the formation of a "modern" protein, or even a complete bacterium with all "modern" proteins, by random events. This is not the abiogenesis theory at all.
2. They assume that there is a fixed number of proteins, with fixed sequences for each protein, that are required for life.
3. They calculate the probability of sequential trials, rather than simultaneous trials.
4. They misunderstand what is meant by a probability calculation.
5. They underestimate the number of functional enzymes/ribozymes present in a group of random sequences.

Analysis

Hoyle's fallacy derives from disregarding everything about sequence space other than its size. Two factors are conflated: the probability of getting a 'first sequence' (abiogenesis or novel function), and the probability of going anywhere else (evolution). This may be illustrated by dissection of Hoyle's argument made in relation to myoglobin. Any sequence of repeated elements – for example, DNA or protein – generates a sequence space for n positions and v different values at each position of vⁿ possibilities. Therefore myoglobin, a protein of 153 amino acids, has a probability, in a 'random-amino-acid machine', of 20⁻¹⁵³ of occurring in one step. For this to have any evolutionary significance, the number of useful myoglobins in that sequence space would have to be exactly 1. Further, any space of vⁿ elements includes all lower-order spaces: {{v^{n-1, n-2, n-3 ...}},{(v-1)^{n, n-1 ...}} ... }. A probabilistic analysis must consider the smallest such space that contains a functional myoglobin. Neither n=153 nor v=20 can be accepted as minimal requirements, a priori.

Myoglobin function is in fact a property of the folded protein, not the amino acid sequence, per se. Protein folding is indeed determined by its amino acids, but activity is determined within a three-dimensional space. Certain key functional groups require suspension in a tightly-specified spatial orientation, but many different sequences may perform the scaffolding task of holding these in place. Even an imperfect arrangement may be superior to its predecessor, while adaptive evolution has the capacity to channel random processes along paths of optimization. If multiple functional sequences and adaptive gradients exist, then the total size of a sequence space delimited by a single modern instance does not set an upper bound on the probability of achieving a functional arrangement.

The minimum sequence of a functional myglobin, the distributions of functional sequence within the total space, and the adaptive benefit of variant sequences within organisms are all unknown. Without such information, the probability of generating a functional myoglobin cannot be calculated.

Reception

Hoyle's Fallacy is rejected by evolutionary biologists, since, as the late John Maynard Smith pointed out, "no biologist imagines that complex structures arise in a single step." The modern evolutionary synthesis explains how complex cellular structures evolved by analysing the intermediate steps required for precellular life. It is these intermediate steps that are omitted in creationist arguments, which is the cause of their over-estimating of the improbability of the entire process.

Hoyle's argument is a mainstay of creationist, intelligent design, orthogenetic and other criticisms of evolution. It has been labeled a fallacy by Richard Dawkins in his two books The Blind Watchmaker and Climbing Mount Improbable. Dawkins argues that the existence of God, who under theistic uses of Hoyle's argument is implicitly responsible for the origin of life, defies probability far more than does the spontaneous origin of life even given Hoyle's assumptions, with Dawkins detailing his counter-argument in The God Delusion, describing God as the Ultimate Boeing 747 gambit.

See also

• Watchmaker analogy
• Objections to evolution
• Infinite monkey theorem

External links

• "A memorable misunderstanding" Fred Hoyle's Boeing-story in the Evolution/Creation literature by Gert Korthof
• Evolution Encyclopedia Vol. 1 Chapter 10 Appendix Part 2 Contains a number of Hoyle quotations on evolution.