A theory has to have a basis, in fact, it must have a very strong basis. A theory is a scientifically acceptable principle that is offered to explain a vast body of facts, and is supported by an overwhelming body of evidence. You can’t have a theory before you have the evidence.

But to the average Jane or Joe, a theory is just an idea that lives in someone’s head, rather than an explanation rooted in experiment and testing. However, theory isn’t the only science phrase that causes trouble. Even Allain’s preferred term to replace hypothesis, theory and law — “model” — has its troubles.

1) hypothesis an educated guess about a possible solution to a mystery; a prediction or statement that can be tested; A reasonable or educated guess; what a scientist thinks will happen in an experiment.

The scientific definition of the word “theory” is different from the definition of the word in colloquial use. In the vernacular, “theory” can refer to guesswork, a simple conjecture, an opinion, or a speculation that does not have to be based on facts and need not be framed for making testable predictions.

” A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. Such fact-supported theories are not “guesses” but reliable accounts of the real world.”

Charles Darwin

Abstract. In 1868 Charles Darwin proposed Pangenesis, a developmental theory of heredity. He suggested that all cells in an organism are capable of shedding minute particles he called gemmules, which are able to circulate throughout the body and finally congregate in the gonads.