I agree with applestar, probably two different pests attacking your poor pepper plant, which will not survive at this rate, unless you can do something about this.
As soon as I read your title, I thought slugs/snails, because that's the only thing that ever eats my peppers. And slugs are invisible, because they only come out late at night. The only way you will ever see them is to come out late at night or very early in the AM with a flashlight and check your plants over (undersides of leaves and leaf junctions). Or you can lay a board flat on the ground near the plant, with one end elevated just a bit. Come back a couple days later at mid-day and you will likely find your culprits hiding under it. The rounded/oval holes in the middle of leaves are very typical slug/snail damage.
The chewed up leaf edges are something else, most likely some kind of caterpillar. Tobacco/ tomato hornworms will attack pepper plants also as will beet armyworms and other caterpillars. The hornworms are invisible by being very well camouflaged, exactly the color of the leaves:
http://www.gardenandflowers.com/images/ ... 00x800.jpg
In this picture you can see how it is biting a semi-circular hole out of the leaf edge. In this thread http://www.helpfulgardener.com/forum/vi ... 91#p372091
I made a post about identifying your pest by the damage it leaves. I think it is interesting.
Fortunately for you, there is one solution to all these woes. (Food grade) diatomaceous earth works against anything that crawls over it, including slugs and caterpillars. You will need to be diligent about it. It needs to be reapplied after every rain. Scatter it generously on and around your plant. It is harmless to you or your pets etc. You don't know it, but you have eaten it-- stored grains are often treated with DE to keep insects out of it.
Best wishes! Keep us posted how it goes for you.