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.
Since we proposed punctuated equilibria to explain trends, it is infuriating to be quoted again and again by creationists-whether through design or stupidity, I do not know-as admitting that the fossil record includes no transitional forms. Transitional forms are generally lacking at the species level, but they are abundant between larger groups.
To command their professors of astronomy to refute their own observations is to command them not to see what they do see and not to understand what they do understand.
When we have any function, whether it's language or vision or cognitive functions like memory, we aren't dealing with a straight line to the brain that says 'This is what I do.' The brain builds a network of connections, a network of neurons that have a particular role in that function.
Considering their impact, you might expect mosquitoes to get more attention than they do. Sharks kill fewer than a dozen people every year, and in the U.S. they get a week dedicated to them on TV every year.
I protest against the use of infinite magnitude ..., which is never permissible in mathematics.
The work on ants has profoundly affected the way I think about humans.
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