Originally posted by arnold I find the underlined sentence at odds with your description of a fielder successfully accomplishing a skilful feat in the real world. A couple of years ago I took a course on the history of philosophy and the world views offered by philosophers through the ages. All were trying to makes sense of how we know things. Other than Aristotle, so many others had to find some way of validating their worldview that did not depend on their perceptions. They simply refused to accept the evidence of their senses as a primary. Descartes for example used a convoluted reasoning that since he could think, he must exist. In short, nearly all tried to DEDUCT through pure reason (Hello Kant) how we knew what we knew. If I remember correctly, Hume realised his rationalizations while flawless, should be ignored if one wanted to live in the real world.
The deductive is seductive -- logic is far cleaner and more absolutely true or false than any possible statement about the natural world. If one seeks certainty, math and logic tied to a simple fixed corpus of axioms are the way to go. Of course the real world isn't listening to the incantations of the rationalists and even logic loses its certainty if one starts looking at complex things like arithmetic and must face Godel's scary theorem. It's more than a little ironic that an animalistic subjective desire for stability lead the rationalists' so astray.
Originally posted by arnold But our senses are our only direct cognitive contact with reality and, therefore, only source of information. Without sensory evidence, there can be no concepts; without concepts, there can be no language; without language, there can be no knowledge and no science. Aristotle looked to the outside world for answers, St Augustin looked for truth in the Bible.
By undercutting the validity of the senses we cut ourselves off from the real world. Try to disprove the evidence of sensory perception without using data obtained from such perception.
This is very very true -- the senses are our channel by which our internal thoughts get information about external conditions.
However, information theorists would categorize the human senses as noisy channels with both stochastic and deterministic sources of error. There are several fascinating branches of science spanning cognitive science, neuroscience, and behavioral economics that delve into the deep discrepancies between Homo sapiens and the fairy tale concept of rational man. One really can't trust one's senses to the last iota which is why some much of science involves building measurement instruments that end up having better repeatability than human senses do.
Originally posted by arnold As for "certainty", it is possible - in a given context. Water will boil at x* at a given altitude and pressure. Dropped objects will fall to earth but not if accelerated to 17000 mph. There are no absolute (without context) certainties other than perhaps that nature to be commanded needs to be obeyed.
"Certainty" is elusive! First, one can heat water above its normal boiling temperature under some conditions (e.g., one exception is a clean smooth-walled container and water free of any bubbles which can easily happen when microwaving a cup of water). Second, a dropped helium ballon or butterfly typically does not fall to earth.
These exceptions aside, science has done a pretty good job of sensing, detecting, and characterizing the many natural phenomena that affect thermodynamic states, physical motion, and many other things. And engineers have become quite adept at applying this scientific knowledge to build things that reliably do what people would like them to do. It's a happy marriage between inductive and deductive techniques.
But any certainty offered by science or engineering comes with fuzzy limits defined by the limits of the science (the span and density of experimental conditions) and the limits of the considerations and approximations used by the engineers. For example Ricoh says its cameras can operate between -10°C to 40°C(14°F to 104°F) based on how its engineers designed the camera. However, the basic materials and physics of the camera are likely stable over a broader but unknown temperature range.