I was rather shocked to read John criticising people for merely floating a theory that agreed with the evidence as they saw it, and was pretty simple. It’s not as if they were claiming any alternative was impossible. The job of the scientist is to explain evidence, and it’s often best to start with the simplest explanations possible in the light of current observations. John was commenting on stone tool cultures (below is my collage of plates of tool cultures from Don Johanson’s institute’s nice summary in their interactive documentary of the four main ones, with ages reflecting a position as of 2008. Click to enlarge).
On what those found in India might (or might not) tell us about one wave of humans moving out of Africa, John Hawks says:
“Notice however, the intrinsic nuttiness of archaeological interpretation. Oh, we have the first evidence for Acheulean in India around 600,000 years ago? Well, that’s around the same age as the Bodo fossil from Ethiopia! What a coincidence! Maybe this new kind of hominin expanded from Africa and carried the Acheulean to India! And Sima de los Huesos is around 600,000 years old, too — and there’s a handax in the pit! My gosh, we need a name for those hominins!
Well, the nice thing about a hypothesis built on mere coincidence, is that it only takes one observation to falsify it.”
To start at the end, there can never be anything shameful about a hypothesis being vulnerable to a single contra-observation; indeed it’s shameful to make such a criticism. Next, making fun of hypotheses constructed from coincidences is like making fun of people who go to the toilet. Either John is hoping for a mechanism to demonstrate something beyond coincidence (but you must not criticise a theory that as yet has no mechanism – the wise learned that from the plate tectonics saga) or he expects a good theory to be provable as true, not even subject to potential refutation. You must also not expect a theory to be understood perfectly in exquisite detail while still in its early stages, and coincidences are at the heart of most if not all valuable discoveries. The last sentence of the quote suggests the author expects more from a theory than that it must be potentially refutable, and need only be a conceptual model that could generate the observations.
To clarify, our minds have a terrible tendency to create explanations. Terrible in the sense that it’s an inescapable tyranny, but wonderful in its usefulness, even though some explanations seem bizarre, later or even at the time. How we commonly generate these explanations, or assign favour to them, it’s better not to ask since the answer will be very complex, surprising, and often embarrassing. In science though, we often create a Null Hypothesis, which we then seek to refute through our observations. We only do this in order to accept the Alternative (or Experimental) Hypothesis which, through being the exact opposite (‘complementary’ and ‘mutually exclusive’) can be accepted if we accept – note, not prove – that its opposite the NH is false. But we most certainly do not take the Null Hypothesis as being more acceptable prior to the experimental analysis! Since it cannot be justified in almost any situation that one hypothesis is the NH or even its opposite the AH, we couldn’t insist anyway that some theory or other be favoured without prior knowledge. We must often construct hypotheses based on inadequate observations (indeed life seems to me to be a game where your most important moves must be made before you’ve had an opportunity to master the rules) yet it’s pointless to say it’s wrong to try. Quite apart from anything else, no statistic will ever give certainty.
“Ideas are so fragile. It’s so easy to miss an idea or snuff an idea out” Jonathan Ive in ‘Stephen Fry in America’ BBC.
ж 5: It can be good science merely to “rough out” a theory or a class of theories for consideration.