Humans Have a Physical Nature

    When we look at the world using physics, we discover that it is composed of matter and energy.  This matter and energy propagates in time according to the laws of physics.  When we look at ourselves, we find that we are composed of the same types matter and energy.  A large fraction of the sun is hydrogen.  A large fraction of each human is hydrogen.  Much of the crust of the earth is oxygen.  A large fraction of each human is oxygen.  The difference between us and the sun and the earth is largely the exact percentages of each element, but more importantly, how those elements are connected to each other.  In humans, oxygen, carbon, and hydrogen form highly-ordered chains and structures, while highly-ordered structures are typically not apparent in objects that are not alive.

    Not only are the contents of humans similar to that of the rest of the universe, but both we and the universe are bound by the same laws of physics.  In our brains are about 100 billion neurons.  Each of these neurons propagate signals down their axons (output fibers) by pushing ions across boundaries in a specific electrochemical process.  This process is well understood in terms of the laws of physics.  When we eat, we extract chemical energy from the food, so that we may use it to walk, talk, and think.  Every process in the body that has been scientifically measured is similarly bound by and takes advantage of the laws of physics.  These same laws of physics can be used to understand electrochemistry in a battery, the motion of the planets, and nuclear reactions in the sun.

    Are humans completely physical?  That is, can everything about humans be explained by physics?  No.  The complexity of humans, especially their brains, lies well beyond the means of experimental and theoretical science.  However, this may just be a limitation of our current science.  Physicalists believe that humans are (or more accurately, everything is) entirely physical, every future discovery in science will confirm this, and future science will be similar in methodology to current science.  Physicalist is the modern philosophy term.  Historical philosophers as well as modern and historical theologians typically call this belief materialism.  However, there exists some data in the universe that can never be understood with science.  To see this, we turn to the knowledge argument.

This page was last changed on 2007/12/28