First: never use a long word if a short word will do.
Second: if you want to make a statement with a great many qualifications, put some of the qualifications in separate sentences.
Third: do not let the beginning of your sentence lead the reader to an expectation which is contradicted by the end.
Take, say, such a sentence as the following, which might occur in a work on sociology: ‘Human beings are completely exempt from undesirable behaviour-patterns only when certain prerequisites, not satisfied except in a small percentage of actual cases, have, through some fortuitous concourse of favourable circumstances, whether congenital or environmental, chanced to combine in producing an individual in whom many factors deviate from the norm in a socially advantageous manner.’
Let us see if we can translate this sentence into English. I suggest the following: ‘All men are scoundrels, or at any rate almost all. The men who are not must have had unusual luck, both in their birth and in their upbringing.’ This is shorter and more intelligible, and says just the same thing. But I am afraid any professor who used the second sentence instead of the first would get the sack."This suggests a word of advice to such of my hearers as may happen to be professors," Russell writes.
I am allowed to use plain English because everybody knows that I could use mathematical logic if I chose. Take the statement: ‘Some people marry their deceased wives’ sisters.’ I can express this in language which only becomes intelligible after years of study, and this gives me freedom. I suggest to young professors that their first work should be written in a jargon only to be understood by the erudite few. With that behind them, they can ever after say what they have to say in a language ‘understanded of the people’. In these days, when our very lives are at the mercy of the professors, I cannot but think that they would deserve our gratitude if they adopted my advice.If professors can learn to write without jargon, why can't writers of business prose?