It is really amazing how closely purpose and design are related, and their further relation to the problem of evil. Before someone can design some device, they must have a purpose- they don't just start throwing stuff together and find a purpose for it later. Likewise, end-users look at devices and see specific purposes for them. The sane end-user would not conclude that the useful device was not designed. Granted, some devices take on purposes different from the original; however, the device still has purpose, otherwise it would not be in the market.
True design is never attributed to unconscious sources. Right now, I am setting on my couch, watching my LCD TV, being cooled by an air conditioning unit in a room lit by fluorescent lights. Each device has a specific purpose, specifically identified. I do not have to personally know the inventor of these devices, nor do I need to see the plans behind each to know that they have a specific purpose. From that, I can infer that they had a designer. It would be ludicrous for me to attribute these "designs" to an unconscious source. Even if I were to look at the level of complexity of each device relative to the others, I would not be justified in concluding that the one with the least amount of complexity is not designed. They all have purpose; they all have designs; they all have designers.
Anytime someone is asking "why?", they are assuming that a purpose behind something exists. If someone who had never seen an LCD TV before, asked "why have such a device?", the answer would not be able to be communicated without mentioning its purpose. Likewise, many people ask me "why" I took a certain course of action in my troubleshooting of computer issues. They ask it anticipating that I had a purpose. Which, they are correct, and I explain my purpose behind specific steps. If I were to tell them that I had no purpose, they would conclude that anyone (or anything) could have done and accomplished the same "purpose". If the step was conducted automatically by some source other than a person, it would not make sense to even ask the question (unless the person who is the source of the design of the process, is available; but then we're back to a designer). The "why" question not only cannot be answered, but there is really no need to even ask it.
My point is that in everyday life, we would not assume a purpose, while trying to deny a design(er). The fact is that people assume one while trying to deny the other all the time. I was asked the other day why God would allow a certain (bad) thing to happen to a child. This person (and many others) typically use this type of question as a reason to dismiss the idea of an Intelligent Designer. Unfortunately for them, by asking "why?", they are assuming an end purpose with a mind behind it. If such a purpose exists, a design exists. If a design exists, a designer exists.
This type of question is an effort to "have one's cake and eat it too". A person cannot assume a purpose without being forced to assume a designer. A person also cannot deny a designer without being forced to deny a purpose.