It seems to me that the certainty of what is real is contained within our mental record of what we have learned in our experiences as well as what our senses tell us is before us. Our senses tell us the flat smooth surface raised on four legs is a table. Our experience with tables is that a chair fits well under it, things rest upon it and some times, with too many drinks, people dance on them. We also know these tables have weight limits. Is the table real? In every sense that we can understand whether we or anything else is real, the table is real.
The concept stated above follows suit with Hume’s empiricism theory. David Hume’s believed knowledge and objects are real based on the idea and the demonstrating of the knowledge or object. Sensing the table combined with using the table make it real.
Hume’s theory does not account for those things that we have no first hand sense of but only knowledge or the opposite, sense without knowledge. For instance, I have knowledge of Mt. Everest and its challenging terrain for climbing. I have never been to Mt. Everest or faced the terrain to have sensory data backing my knowledge. This lack of sensory data does not mean Mt. Everest is not real. It simply means it is more real to those who have climbed Mt. Everest.
It is possible for individuals to have varied sense of realness in relation to different objects of ideas. A Neurosurgeon has knowledge and sensory data supporting the realness of the brain. It gives the brain added real elements for the neurosurgeon that a stock broker could read an article about but not receive identical sensory data regarding. The same goes for a golfer. A golfer knows the difference between various clubs and their impact on the golf ball first hand in knowledge and sensory data. A non-golfer views a club as a club even if there is a general knowledge that the difference in clubs somehow effect the golf ball differently. In each instance the brain and the clubs are not tangibly more or less real but individually vary in realness based on the individuals interaction with the subject or object.
Essentially, the theory rests itself in both the explained and unexplained. The explained is in science such as atoms and physics but the unexplained is in perspective and personal experience. While skepticism is a huge proponent in Hume’s theories of knowledge I feel Hume’s is more solid in his concepts than Descartes.
Descartes seems to prove more inconsistent in his dream theories. There are dreams that do not involve flying, talking animals or upside down rooms. There are dreams that seem very much like real life in their dialogue, scenery and presented situation. It would seem difficult to tell the difference between dream state and reality based on these sort of dreams. The certainty of separating dreams and reality seems to be that the questioning of being awake stops when one is awake. Outside of sleeping people tend to not question their conscious state.
It is not to say that Descartes’ questioning is unwarranted. There are moment in which habit becomes so strong in a persons conscious state that they are able to complete activities without memory of the event. People sometimes drive home or to work without remembering the trip. People wind up at work on a Saturday or calling a regular client on a holiday due to habit. Descartes may argue that habit is a theory worth using to question consciousness and its awake / dream state.
It can be argued that a person knows they are awake because they go to the bathroom, brush their teeth, taste the banana they eat, feel the water they shower under, or see the steam rising from the warm mug of coffee in their hands. The trouble is with technology where it is today the simulations of these things are not that far away. There are a number of recent movies that have touched on the ability of technology to manipulate our mental selves into believing we are different physically in self and scenery. Descartes is not wrong to question the tangibility of our conscious states. Mental illness and drug use, illegal or medicinal, are things that produce strange bending of so called reality. It is quite possible that what seems unbelievable today will be completely believable tomorrow.
After all, now we know the world is round and revolves around the sun.