What and Why?

Jean le Rond D'Alembert did many great things and you can find out more about that on the Discoveries page. This page is to prove to you how great his discoveries actually are and to tell you a little bit about why he might have decided to do some of the things he did.

What probably made D'Alembert most famous, out of all the things he did, was his principle, which was named after him. If D'Alembert's principle didn't exist today, we wouldn't know "internal forces of inertia" (that is, forces which resist acceleration) must be equal and opposite to the forces which produce the acceleration. This may be inferred from Newton's second reading of his third law of motion, but the full consequences had not been realized previously. The application of this principle enables us to obtain the differential equations of motion of any rigid system. (From A Short Account of the History of Mathematics (4th edition, 1908) by W. W. Rouse Ball.) I  don't understand the principle, so I don't know what the consequences would be.

If he hadn't discovered this principle, then so many other things wouldn't have been discovered or invented because later on in history people built onto his basic theory and did different things with it. Such as, after quite a bit of time they used his information to understand and figure out how to measure sound waves. If this discovery hadn't been made, many things and people would be different. Therefore, it is a great discovery that made a notable contribution to the world.

D'Alembert was a simple man, and led a simple life. His goal was never to become rich, and if he ever had some extra money he'd donate it to charity. He was a  giving man because he wanted people who had terrible lives, like himself when he was young, to be happy, or at least he wanted to help them a bit. He was a typical 18th century philosopher, and the eighteenth century was in the period of time that is called the age of reason, or the age of enlightenment. This was the time in history where people wanted to know the scientific explanations of things that before they had just relied on what their religion, priest, or bible said. They were just starting to realize that there were actual reasons for things being the way they were, scientific reasons. For example, before they might have just not really thought about sound and how it travels, but they were starting to think, hey wait, we might be able to measure sound and find out how it works. In his actions he showed that he liked this period,  that it was a good way of living, and that more people should live this way. One of the things that he did was to try to get people to live the way he did, and to help make the encyclopedia. This encyclopedia encouraged scientific thinking because it started to explain some of the many things that before had been explained only through religion.

Why did D'Alembert help with the making of and the editing of the encyclopedia? Why did he work so much with laws of nature, and theorems? Why did he do all this instead of lying around doing nothing, or working? Did he think it would make a difference in the world or did he just want people to know and remember him and write about him in the future like I'm doing now?

Well why don't you think about all these things and vote on why you think he did what he did. This isn't a right or wrong type of thing; it can't be a right or wrong thing because we just can't possibly know what he was thinking without some proof, a diary or such. This is an opinion poll, and we'd really like to know what you think, so please vote. If what you think isn't on the poll that doesn't mean that it's a bad choice, it just means that we didn't think of it. If this happens please choose other and then if you'd like you can email us your idea and we'll put it as a choice, who knows, maybe tons of other people think that too.

After you choose, the screen will pop up with what other people have voted so far and my opinion on his motivation. You'll also see a good quote by his foster mother about philosophy.

What do you think his motivation was? (That's the short form of the question, the long form is up there in a couple paragraphs.)