[The Cloud]

You're right, you can believe whatever you want and justify it because, at its root, all philosophy is based on fundamental principles that can have no proof. It's similar to fundamental principles in physical sciences, such as the speed of light in a reference frame. Light always moves at the speed of light relative to an object, no matter how fast that object is moving. There is no explanation for this, no more basic principle known that guides this behavior. It simply is, arbitrarily.

The same with philosophy. You can distill your beliefs down to the basic core, but no further. And that core is arbitrary, depending on what assumptions you want to make. A core assumption that other people are similar beings to yourself and thus deserve the same rights will result in drastically different behavior from a core assumption that other people are not similar beings and thus do not necessarily deserve the same rights. Both of these core assumptions can be justified through observation, but neither can be proven.

So reason, the most necessary tool in philosophy, is flawed because it is not reality. It can only crudely approximate the laws upon which your world operates on, based on assumptions that it cannot prove. It is just a tool, it is not reality. Just like you can create a computer program that will model this or that physical phenomena, but not one that recreates it, because if the program perfectly modeled the phenomena then it would be the reality itself.

So reason is self-limiting. It defines it's own bounds, and while it can catch glimpses of reality it will never quite be real. That's not to say it's useless, just like the computer model isn't useless. But it's not reality, it's just a tool. You are reality, not reason. Don't confuse yourself with your thoughts, thoughts are just tools. You are the reality of the experience, which can't be put into words and structured into diagrams.