This morning I woke up thinking about this question, as it has tended to raise my ire on more than one occasion. The first time I heard the word modern used in a limited way was in an early (in my life, that is) art history class. The professor said modern art was the style of art created from about 1900 to about 1950. I became red faced angry at this limiting of such a universal thought/idea captured in a word. Modern, in my mind, is anything new, or advancing culture. What we do today is modern, not post-modern, which is a reference I really hate. By capturing a word like modern and encasing it in a time frame, we lose an infinately useful term in our vocabulary. The wheel is a modern invention.
I checked out the word on Wikipedia and am dissapointed in their treatment of it. However, if you link to present time , which they have linked to another article connected to modern, you begin to get a little closer to the elusiveness of this word and the ideas attached to it.
Rigor is expected from academia and is becoming more and more an essential aspect of the internet. Checking sources for information and turning assumptions and "conventional widom" on its head is entirely possible with the vast data available here, quickly. Seth Goodin discovered very quickly yesterday the Windy City is called the Windy City because of weather, not politics, and corrected his earlier post.
Let's talk about modern, modernism and modernity, from a philisophical point of view, not from the conventional wisdom, because conventional wisdom is more often wrong than not.
I look forward to the deepening of human thought with the help of the internet. Our ability to immediately talk, debate, reframe and reexamine our assumptions about so many things takes my breath away. Understanding truth has never been more possible.