Previously I have commented on differences between Physics and Philosophy. Recently I noticed another example of the difference between the two: Physics is self-correcting, while Philosophy is not. To show this I will use an experience I had recently while grading homework for a class that I am a TA for.
The homework problem involved finding the velocity of a bicyclist as he peddled along. The students were given a constant power output from the rider and then they had to find the rider's terminal velocity. They went through a process where they solved some basic equations and then they added in air resistance and solved the more complex equations numerically (which means they wrote a computer program to solve the equation).
One of my students solved their equation and found the terminal velocity and then displayed a graph of their velocity versus time, or how their velocity changes over time:
If you look at this graph and understand what it is showing you will realize that the student made a mistake. To understand the mistake allow me to interpret this graph physically. At the beginning of the race the biker starts at rest (the extreme left of the graph where t = 0 and v = 0). They start to speed up (velocity is positive) and they continue to ride faster and faster. At some point their speed maxes out and they begin to slow down. At this point this is fairly normal for anyone riding a bike, but what happens next according to the graph is not normal. The rider continues to peddle at the same rate that they started out at, but because of air resistance they begin to slow down (I must point out that there is no wind) until after about 27 seconds they begin to travel backwards! And this happens simply because they are riding through air, with no wind! Obviously there was a problem with their equation, and upon inspecting their equation I quickly found what their error was, they had forgotten one variable in a single term of their equation, and that made all the difference.
My point with this is when a mistake was made we could look at the results and compare them with reality to see if it made sense. In other words we had a check or test to make sure we had done it correctly or whether our theory was correct. In the case of Physics, no matter what the theory is, the science itself has built into it a self correcting mechanism. Whenever a mistake is made something can be done to test it and to correct the mistake. The critical test come in comparing our calculated results to the physical world. All our theories and calculations mean nothing if they cannot predict what is observed in the physical world. It does not matter how "elegant" a solution is, it is of no worth if it does not correctly demonstrate some physical principle.
Philosophy on the other hand does not have this ability, as a matter of fact the vast majority of Philosophy openly denies and/or questions the validity of the very thing that can show whether or not an idea is correct (such as Descartes' method of doubt and Kant's noumenon). This means that Philosophy, as a whole does not have any mechanism to check and to self-correct incorrect theories. With no way to check whether or not something is correct or true it is no wonder that there is so much confusion in Philosophy. If the same were true of physics we would live expecting people to ride backwards on their bikes, rocks to fall up and electricity to flow into wall sockets. We would loose all sense of order and normalcy in the world. If you wonder why Philosophy is so hard to understand, or why it returns ideas that are inconsitent with expereince, it is because it has divorced itself from the very thing that would give validity to its ideas.
It is like quitting your job and then wondering why you are poor.