Karl Popper (1902-1994) argued that science must be based on statements that are falsifiable. One researcher makes a statement, perhaps in a published paper, others check it out and, if they can prove it to be false, the statement is rejected. If not, it is accepted as probably true, at least for the time being. A statement that can be tested and proved true or false is scientific. A statement that cannot be tested that way has no place in science.
Of course, that depends what you accept as valid evidence. The last witch was burned in the UK in 1727. We no longer test people to see if they are witches because, mostly, we don’t believe in them. It used to be accepted that having an extra nipple or a wart was proof you allowed the devil to suckle from you, but now we discount that as invalid evidence. So we can argue about what each generation, or even interest group, accepts as valid testing and valid evidence. Many people still refuse to accept that climate change is a serious and man-made problem as they refuse to accept ‘evidence’ which others call scientific. Sometimes, of course, it is inconvenient to accept scientific evidence. Companies making and selling sugar won’t be too keen to accept that eating it to excess is a major problem in UK diets and convenience foods. There is a difference between testing scientific theories and making them widely known then publicly acceptable. And ‘academic research’ may not always be objective and neutral.(note 1)
But arguing from a self-interested or even dishonest point of view is one thing – arguing within paradigm is another.
A paradigm is a set of thoughts, ideas or assumptions which, taken as a whole, tell you what is valid or invalid in any field of research. There used to be two views of how the sun and planets behaved. The geocentric or Ptolemaic model said the earth was at the centre of the universe and the sun moved around us. This made perfect sense according to what people could see and allowed mariners to make charts and navigate quite well enough to explore the world and get home safely. There was no need to challenge it, especially as it allowed us to believe God made us at the centre of his universe, to be special. The geocentric paradigm ruled and nothing outside it was taken seriously.
When Copernicus (1473 – 1543) decided after extensive observation and modelling that the earth moved around the sun, he knew his heliocentric model would be controversial as it upset the paradigm. Galileo (1564-1642) supported the new model but the church set the Inquisition on him as his ideas seemed heretical, demoting our place as God’s special centre of the universe. He was placed under house arrest.
If a paradigm tells us what to take seriously we can only think within its limitations unless we accept a serious shake up of our fundamental assumptions. This is always hard to do and may be resisted for both honest and dishonest reasons.
Then, of course, we have the limitations of our own language.