Suppose there are two goods, food and clothing. My preference has the following properties: 1. I am rational.
2. I need at least one unit of food and one unit of clothing in order to survive.
3. I strictly prefer surviving over not surviving.
4. I am indifferent over all situations in which I do not survive.
5. When I have strictly more than one unit of each good, I satisfy monotonicity and strict convexity.
6. When I have strictly more than one unit of each good, I have a positive marginal rate