Observation, Theory, and Reality

We continue our series of excerpts (and discussion) from the outstanding survey paper by George F. R. Ellis, Issues in the Philosophy of Cosmology.

8.3 Limits of Representation and Knowledge of Reality
It follows…that there are limits to what the scientific method can achieve in explanatory terms.  We need to respect these limits and acknowledge clearly when arguments and conclusions are based on some philosophical stance rather than purely on testable scientific argument.  If we acknowledge this and make that stance explicit, then the bases for different viewpoints are clear and alternatives can be argued about rationally.

We human beings want so badly to be able to explain our existence and existence itself that we tend to “fill in the blanks” and treat speculation (no matter how well reasoned) as if it were something akin to fact.  This is true for both science and religion.  A more reasonable approach, it seems to me, is to reject absolute certainty—especially where physical evidence is sparse or nonexistent—while always striving to deepen our understanding.  That is the scientist’s stock-in-trade—or should be.  Each of us needs to become more aware of the limitations of our understanding!

Thesis F6: Reality is not fully reflected in either observations or theoretical models.
Problems arise from confusion of epistemology (the theory of knowledge) with ontology (the nature of existence): existence is not always manifest clearly in the available evidence.  The theories and models of reality we use as our basis for understanding are necessarily partial and incomplete reflections of the true nature of reality, helpful in many ways but also inevitably misleading in others.  They should not be confused with reality itself!

We humans create our own “realities”, but under the very best of circumstances (science, for example), our “reality” is only an imperfect model of what actually exists.

The confusion of epistemology with ontology occurs all the time, underlying for example the errors of both logical positivism and extreme relativism.  In particular, it is erroneous to assume that lack of evidence for the existence of some entity is proof of its non-existence.  In cosmology it is clear for example that regions may exist from which we can obtain no evidence (because of the existence of horizons); so we can sometimes reasonably deduce the existence of unseen matter or regions from a sound extrapolation of available evidence (no one believes matter ends at or just beyond the visual horizon).  However one must be cautious about the other extreme, assuming existence can always be assumed because some theory says so, regardless of whether there is any evidence of existence or not.  This happens in present day cosmology, for example in presentations of the case for multiverses, even though the underlying physics has not been experimentally confirmed.  It may be suggested that arguments ignoring the need for experimental/observational verification of theories ultimately arise because these theories are being confused with reality, or at least are being taken as completely reliable total representations of reality.

Absence of evidence is not evidence of absence.  But, without evidence, all we have is conjecture, no matter how well informed.  As Carl Sagan once said, “Extraordinary claims require extraordinary evidence.”

No model (literary, intuitive, or scientific) can give a perfect reflection of reality.  Such models are always selective in what they represent and partial in the completeness with which they do so.  The only model that would reflect reality fully is a perfect fully detailed replica of reality itself! This understanding of the limits of models and theories does not diminish the utility of these models; rather it helps us use them in the proper way.  This is particularly relevant when we consider how laws of nature may relate to the origins of the universe itself, and to the existence and nature of life in the expanding universe.  The tendency to rely completely on our theories, even when untested, seems sometimes to arise because we believe they are the same as reality—when at most they are descriptions of reality.

Ellis makes a pretty good case here against dogma.  Though he does not specifically mention religion (and why should he, as the subject at hand is cosmology), I do think these ideas apply to religion as well.

Always a journey, never a destination.

References
Ellis, G. F. R. 2006, Issues in the Philosophy of Cosmology, Philosophy of Physics (Handbook of the Philosophy of Science), Ed. J. Butterfield and J. Earman (Elsevier, 2006), 1183-1285.
[http://arxiv.org/abs/astro-ph/0602280]

We Miss You, Carl Sagan

It is hard to believe that Carl Sagan has been gone now for 20 years.  In fact, he died on this day in 1996 of myelodysplastic syndrome at the age of 62.  He was one of the 20th century’s truly great science popularizers.  In addition to writing or co-writing fifteen books, his 1980 PBS television series Cosmos remains the gold standard against which all other astronomy documentaries will be judged.

Here is a listing of Carl Sagan’s books published during his lifetime:

  • Intelligent Life in the Universe (1966; revised and expanded edition of Iosif Shklovsky’s 1962 book of the same name)
  • Planets (1966; one of the LIFE Science Library series)
  • The Cosmic Connection (1973)
  • Communication with Extraterrestrial Intelligence: CETI (1973; Carl Sagan, editor)
  • Other Worlds (1975)
  • The Dragons of Eden: Speculations on the Evolution of Human Intelligence (1977)
  • Murmurs of Earth: The Voyager Interstellar Record (1978; with others)
  • Broca’s Brain: Reflections on the Romance of Science (1979)
  • Cosmos (1980)
  • Contact (1985)
  • Comet (1985; with Ann Druyan)
  • Shadows of Forgotten Ancestors: A Search for Who We Are (1993; with Ann Druyan)
  • Pale Blue Dot: A Vision of the Human Future in Space (1994)
  • The Demon-Haunted World: Science as a Candle in the Dark (1995)
  • Billions and Billions: Thoughts on Life and Death at the Brink of the Millennium (written 1996, published posthumously in 1997)

Carl Sagan’s final interview was with Charlie Rose on May 27, 1996, less than seven months before his death.  You can see it here.

Carl’s daughter, Sasha Sagan, wrote a loving and thoughtful essay in 2014, the 80th anniversary year of his birth.

Here, now, are just a few of Carl Sagan’s most memorable quotes.

Extraordinary claims require extraordinary evidence.

Somewhere, something incredible is waiting to be known.

The size and age of the Cosmos are beyond ordinary human understanding.  Lost somewhere between immensity and eternity is our tiny planetary home.

We make our world significant by the courage of our questions and by the depth of our answers.

A central lesson of science is that to understand complex issues (or even simple ones), we must try to free our minds of dogma and to guarantee the freedom to publish, to contradict, and to experiment.  Arguments from authority are unacceptable.

Science is a way of thinking much more than it is a body of knowledge.

For small creatures such as we the vastness is bearable only through love.

One of the criteria for national leadership should be a talent for understanding, encouraging, and making constructive use of vigorous criticism.

We’ve arranged a global civilization in which the most crucial elements — transportation, communications, and all other industries; agriculture, medicine, education, entertainment, protecting the environment; and even the key democratic institution of voting, profoundly depend on science and technology.  We have also arranged things so that almost no one understands science and technology.  This is a prescription for disaster.  We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces.

Humans may crave absolute certainty; they may aspire to it; they may pretend, as partisans of certain religions do, to have attained it.  But the history of science — by far the most successful claim to knowledge accessible to humans — teaches that the most we can hope for is successive improvement in our understanding, learning from our mistakes, an asymptotic approach to the Universe, but with the proviso that absolute certainty will always elude us.

The Cosmos is all that is or ever was or ever will be. Our feeblest contemplations of the Cosmos stir us—there is a tingling in the spine, a catch in the voice, a faint sensation, as if a distant memory, of falling from a height. We know we are approaching the greatest of mysteries.