From the sentence above, it could look like the first and the second part of the sentence were equivalent. The same confusion seems to infect the minds of most people, with scientists and lay people alike being its frequent victims.
In reality, the sentence above can be more clearly stated as: To show that something exists is different than not showing that something exists.
The argument from ignorance states that a proposition is true because it has not been proven false or that it is false because it has not been proven true. This argument is used by skeptics and believers alike. For example, atheists conclude that God does not exist because its existence has not been proven. On the other hand, believers think that God exists because its non-existence has not been proven, that is to say the statement that God exists has not been proven false. This is a fallacy of informal logic because it excludes a third option, which we’ll see later on.
At least believers can see that they feel or perceive God, and this entity is real for them. On the other hand, atheists only have a lack of evidence because they cannot perceive God. So the burden of proof is on atheists to show that God does not exist.
Both most atheists and believers commit the sin of overestimating human intellect’s capacity, because a failure to see or understand something is taken a level up to imply that something does not exist or is false, completely forgetting that if we do not see something it could be that we’re simply blind.
Aside from the war raging between atheists and believers, this attitude has infected many areas of science but I will deal with those with which I am most familiar. Randomness is the entity advocated by skeptics to deny the existence of other processes, which possess the properties of predictability or purpose.
The argument from ignorance’s fallacy affects biology in a double fashion. The most “ignorant” theory in evolutionary genetics is the neutral theory of molecular evolution, according to which evolution is caused by random drift of alleles that are neutral, thus denying or minimizing the importance of natural selection. Very few geneticists believe that random drift entirely accounts for the evolution of species over time and instead they admit the importance of natural selection.
However, the current consensus is that the genetic mutations that are the material for selection are random. This is based on the absence of compelling evidence to the contrary. To be sure, there is some evidence that genetic mutations are not random, but this is dismissed as preliminary or not strong enough to be taken seriously.
Thus, a lack of strong evidence is taken to imply evidence that intelligent processes do not operate in the arising of genetic mutations.
Not even a complete lack of evidence, but a failure to find “convincing” evidence for the theory that genetic mutations are non-random is taken as evidence for their randonmess. The researcher who tries to find evidence for non-randomness,when failing to find it will conclude that randomness is the real process. Instead, wouldn’t it be wiser to doubt one’s ability to detect deviations from randomness? Especially since life forms are so amazingly complex, beautiful and intelligent. It’s funny indeed how scientists require extraordinary proof for statements that are discordant with (their peculiar form of) common sense, such as the existence of psychic phenomena, but they’re happy to agree with a theory that common sense regards as crazy, that is the creation of complex life forms from chaos, and for which there is no positive evidence but only negative evidence (that is, only absence of evidence that genetic mutations are non random).
When scientists reject the evidence for psychic phenomena, they realize that the argument from ignorance is not sufficient because the evidence for psychic phenoma is indeed quite impressive (25 years of research at Princeton Engineering Anomalies Research Lab and Stanford Institute, plus ganzfeld experiments meta-analazyed with odds against chance that would make any contrarian punter pale and give up). So they have made up a rule that “extraordinary claims require extraordinary evidence”, without specifying what makes a claim extraordinary. This rule is an appeal to common sense, tracing back its origins to Davide Hume, the father of common sense philosophy.
But the common sense of lay people is different than that of scientists. Lay people regard darwinian evolution as crazy and incredible, whereas are more ready to accept the existence of psychic phenomena. So which common sense does science appeal to? The real common sense is that of the lay people, because it’s more “common” than the common sense of scientists, who are a tiny minority of the population.
Having taken Darwin on a stroll with us, we now meet Kendall, the statistician of tau’s fame, whom we’ll happily follow in a random walk to the toilet and let him randomly go down it.
This guy has the merit of having proven to the world that he was a loser as a trader but he turned his failure into an academic win by pretending he had demonstrated that Wall Street (short for all financial markets) is random, or that given a price taken at any moment it is impossible to predict a price at a future moment. This kind of failure is all too common in the traders’ community, with the only difference that traders who lose money usually blame their losses on themselves or at best on bad luck. Kendall instead devised a clever way out of his failure, assuming that because he could find no patterns, there were no patterns, thus the markets must be random. To traders who consistently outperform the market this is pure nonsense, and also to any person with a bit of common sense, realizing that if milions of transactions take place every day in financial markets, they must have a purpose or rational basis, which is the reality that beating the markets is possible, albeit extremely difficult because the market is not (completely) random.