Yes, you can. I only used 1 cup of dried chickpeas, which resulted in about 3 cups of cooked chickpeas. The amount of chickpeas you can cook at once will depend on the size of your pressure cooker. Make sure, no matter which size you have, that you don't go over the halfway way mark with your chickpeas and water. Chickpeas will at least double and usually triple in volume as they absorb the water during the cooking process, so you want to make sure you have enough room in your pressure cooker for the increased volume. If you wanted to cook 2 cups of chickpeas with 4-6 cups of water, you can decrease your pressure cooking time by about 2 minutes. Since it will take longer for the pot to come to pressure (which is cook time), shaving off a few minutes will help to avoid overcooking them. This is not necessary if you want really soft chickpeas for hummus or mashing.