Yes, that's true; but someone with an IQ of 120 should have no trouble grasping the principle in the abstract - or, for example, how it is used in industrial design, even if they wish to deny that applies to living things.
In fact, I think the artificial distinction between micro and macro evolution was introduced because of the difficulty of denying that a population that reproduces with heritable variation, and is subject to variation-dependent selection, must inevitably evolve. And despite the inevitable logic of an accumulation of minor changes producing major changes, it's easier to make a superficially plausible argument-from-incredulity when the timescales involved mean the full transition from minor to major is inferred rather than observed.
To reinvent 'Ev'ry Time We Say Goodbye',
"...There's no theory sager,
but how strange the change from minor to major,
Everytime we say evolution..."
Cognitive dissonance is defined as "an uncomfortable mental state resulting from conflicting cognitions; usually resolved by changing some of the cognitions". A good number of the young earth creationists here seem to suffer from this condition.
Let me attempt to explain. The Christian young earth creationist (YEC) almost always holds that the bible must be understood literally and inerrantly. Based on biblical events and genealogies most YECs believe that the earth was created less than 10,000 years ago. Some will go so far as to claim that it is approximately just 6000 years old. This is based on calculations by Bishop James Ussher (1581-1656) who concluded that:
* the first day of creation was Sunday October 23 4004 BC
* Adam and Eve were driven from Eden on Monday November 10 4004 BC
* the Ark touched down on Mt Ararat on Wednesday May 5 2348 BC
In 1887 Sir John Lightfoot claimed that Adam was created on October 23 4004 BC at 9:00 AM.
On the other hand science in its many disciplines and on the basis of massive evidence claims that:
* the universe was formed by the Big Bang about 13,500,000,000 years ago
* the earth was formed about 4,000,000,000 years ago
* anatomically modern human beings date to about 200,000 years ago
The YEC of course rejects these scientific conclusions in favour of the biblical time line. The odd thing about this rejection is that the YEC will frequently accept other scientific theories and conclusions that do not challenge their biblical understandings.
I am personally convinced that at some level in their psyche most YECs are terribly afraid that science is actually correct and that the bible is wrong. This then is the basis of their cognitive dissonance.
On the other hand, there are a great many Christians like myself who can accept both the findings of science and the bible. There is no conflict in our minds because we realize that the problem is not with the bible itself but in how the bible is interpreted. We can accept that sometimes that the bible is not to be understood literally but expresses itself in allegorically or mythologically.
Some will immediately object that a mythology, being a fiction, is an untruth. The key here is not to ask "Is this story true?" but to ask rather "Does this story work?" Even if one accepts science in general and the theory of evolution in particular, Genesis still works as an allegory of the human condition.
