If everything in chemistry is explained in a satisfactory manner without the help of phlogiston, it is by that reason alone infinitely probable that the principle does not exist; that it is a hypothetical body, a gratuitous supposition; indeed, it is in the principles of good logic, not to multiply bodies without necessity.
Interpretation
The quote suggests that if something can be explained without a certain concept, that concept is likely unnecessary or non-existent.
Antoine Lavoisier’s quote reflects the philosophical principle known as Occam's Razor, which posits that the simplest explanation requiring the least number of assumptions is usually the correct one. In the context of chemistry, Lavoisier argues against the existence of phlogiston, a now-discredited theory, by stating that if a scientific phenomenon can be adequately explained without invoking it, then its existence is likely unwarranted and unnecessary for understanding the principles at play.
In practice
During a science lecture discussing historical theories, this quote can illustrate the evolution of scientific thought.
Imagination, on the contrary, which is ever wandering beyond the bounds of truth, joined to self-love and that self-confidence we are so apt to indulge, prompt us to draw conclusions which are not immediately derived from facts.
We think only through the medium of words. Languages are true analytical methods. Algebra, which is adapted to its purpose in every species of expression, in the most simple, most exact, and best manner possible, is at the same time a language and an analytical method. The art of reasoning is nothing more than a language well arranged.
We must trust to nothing but facts: These are presented to us by Nature, and cannot deceive. We ought, in every instance, to submit our reasoning to the test of experiment, and never to search for truth but by the natural road of experiment and observation.
Perhaps... some day the precision of the data will be brought so far that the mathematician will be able to calculate at his desk the outcome of any chemical combination, in the same way, so to speak, as he calculates the motions of celestial bodies.
It took them only an instant to cut of that head, but it is unlikely that a hundred years will suffice to reproduce a singular one.
While I thought myself employed only in forming a nomenclature, and while I proposed to myself nothing more than to improve the chemical language, my work transformed itself by degrees, without my being able to prevent it, into a treatise upon the Elements of Chemistry.
The atomic bomb certainly is the most powerful of all weapons, but it is conclusively powerful and effective only in the hands of the nation which controls the sky.
On Venus you could cook a 16-inch pepperoni pizza in seven seconds, just by holding it out to the air. (Yes, I did the math.)
Science is not a substitute for common sense, but an extension of it.
People have always asked whether evolution is constantly driving onwards and upwards. Is there always going to be improvement? The answer is no: evolution is a progression of form and function, but it is not purposeful.
The real accomplishment of modern science and technology consists in taking ordinary men, informing them narrowly and deeply and then, through appropriate organization, arranging to have their knowledge combined with that of other specialized but equally ordinary men. This dispenses with the need for genius. The resulting performance, though less inspiring, is far more predictable.
Anyone who attempts to generate random numbers by deterministic means is, of course, living in a state of sin.
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