In science, fact is not the same as truth
Stella Wilson (Write Back, December 1) is correct to point out that "often science has had to change its mind over the years in what it called 'truth'".
This is a result of a confusion between "facts", ie, things that one observes, and scientific "explanations", which try to place the facts in a coherent context.
Perhaps the simplest example is the "fact" that, when something is released from a height, it falls down towards the earth, and explanations of why this happens - Newton's theory that massive bodies attract one another (gravitation), or Einstein's theory that they distort space-time (general relativity).
The more "facts" that fit a particular "explanation", the more confidence one can have in it. This confidence is strengthened if it is able to predict future "facts", but if even only one such future "fact" contradicts its prediction, it cannot be true (though it may still be a useful working tool).
The essential point is that only the "fact" is "true", whereas the "explanation" is merely tentative until "some other theory replaces the present "truth" in future, as Ms Wilson puts it.
Those who claim that science has established the "truth" would do well to appreciate this distinction, rather than assert their explanation dogmatically to silence those who may not accept currently generally accepted theories.
MARTIN D STERN
Salford, Greater Manchester