This is a good topic that I have been considering for some time now. Reading upon the historical text of a knight and his chivarly I have become less inclined to consider myself a knight even though I have obtained the armor of a knight.
First to be a knight you had to pay for the title of knight and you had to own land. Not only those two things, though one had to have an equivaliant amount of soldiers for the amount of land the knight owned. Funding several war horses, armor, esquires, and workers of the land... being a knight was for the elite rich.
Seeing as I have read that a sergeant (A tenant by military service, below the rank of knight) was an individual that had similar if not equivalant armor to that of a knight, however they simply had not met the qualifications to have the title knight.
Then you have your Mercenary. One that is paid to fight (or paid to re-enact)
Now we come to the term of chivalry, (noted this web site is titled Modern chivalry) yet the old term of chivalry. In my opinion a knight displayed chivalry out of fear and greed. First fear, If a knight was not chivalric and killed or mistreated his captured knight (that was held for ransom) certainly word would get around of the misconduct. The knight who gave such horrid hospitality would not be shown mercy (Chivalry) on the battlefield. Then we have greed, why kill your enemy when you can profit from his money.
This comes down to the lesser men on the field, simple men at arms, archers, and the like. They had no money, they were worthless and once a knight made his way to this rank of soldier, the slaughter began. Thay had no use for these men (In select cases, the lesser men and the few that were taken were employed in the farms of their enemies)
and chivalry was not shown to them.
If you were rich and in the club, you were treated the best. If you were poor and outside the club, you were treated like dirt. Chivalry of old... to me was the same as a prejudice.
Kngihts had money, power, control, and they killed (for war, none the less, they killed) add those four ingrediants to any man and they turn out not to be so noble.
In conclusion, there is quite typically the bad with the good. Certainly there were good and noble knights, though imho chivalry was alot darker than the average person considers it to be.