Everyone knows, or at least should know, that scientists often use words in slightly different ways from how they are used by the general public. The words 'evolution' and 'theory' are two obvious examples, but perhaps even more important are the words 'possible' and 'impossible.'

In Genetic Destines, Peter Little writes:

[A] scientist would certainly say that using a strawberry to empty the Atlantic was impossible but would be forced to say that using the coffee cup to do the same was a possible task. In science, there are unambiguous states of impossibility and possibility, but the continuum in-between is poorly served by simple words — scientists will use a mathematical estimate based upon probability.

Even this approach is fraught with difficulty because not all problems are reducible to such analysis and so the way we will overcome these problems is to try and distinguish several words with different meanings within the spectrum. First, an idea can be objectively ‘impossible’ (the strawberry cannot hold water and so it is impossible it can be used to empty something). Second, an idea can be ‘possible’ (a coffee cup can be used to empty a soup bowl), and, finally, it can be ‘impossible practically’ even though it is theoretically achievable (it is impossible practically to use a coffee coup to empty the Atlantic even though a coffee cup holds water).

Even this last use of ‘possible’ also needs one last qualification. ‘It is possible’ does not mean it will happen: so the statement ‘it is possible but unlikely that life on Earth will be obliterated by a meteor before anyone reads what I have written’ uses the phrase ‘possible but unlikely’ to describe an accurate statement concerning an event that is vanishingly unlikely to happen, whereas ‘it is possible I will mistype a word when writing this book’ is a virtual certainty.

When a scientist says that something is “possible,” they mean that it is not impossible — there is a chance, even if vanishingly small, that it could happen. There are no logical or physical barriers that absolutely prevent it from happening under any set of circumstances. When the average person hears that something is “possible” however, they may readily think that it is much more likely than it really is — they can assume that it is realistically possible or even probable.

Language is necessarily vague — every word and every phrase carries a variety of possible meanings, depending upon context. Scientists try to use language as precisely as possible because they are engaged in a pursuit which requires precision. Communicating their findings, though, leads to misunderstandings because of the different ways people use language. We all need to remember this in order to avoid mistakes.

 

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