Stenger starts out with several excellent lines of reasoning.
First he points out that all the models produced by physicists are man-made and that they do not necessarily claim to contain any ultimate truths about the universe. They are just the best efforts available at the moment to explain the observations that are made by experimentalists, and the best test of their value is to see whether they are able to predict things that have not been tested yet. All the best theories can claim to do this, and the ones that are shown to be wrong are not forgotten but generally they are discarded when better models are developed which approximate to reality a bit better.
All today's physics models are based on principles that are used throughout the science. He spends some time explaining that conservation of momentum, angular momentum (or spin) and electrical charge are three of the underlying assumptions in physics. He spend several pages show in mathematics how the special relativity can be applied a lower speeds, deriving familiar classical physics from the more complex models of the last century. He also describes how physics requires that the same answer is reached, whatever the point of view of the observer.
I did mention that his reasoning gets complicated didn't I? Still - with a little persistence I succeeded in skipping over the mathematics and got back to the words without feeling too depressed at my own inadequacy and I think you could do the same if you are equally allergic to maths.
Stenger then goes on to explain that many of the 'fine tuned' quantities are not independent of each other. Proponents of claims of 'fine tuning' seem to think that they can vary one quantity but leave all the others unchanged, even though they might be co-dependent.
Then he describes some of the quantities that are defined arbitrarily on the basis of the scales of units that we have chosen. As such, if we preferred to make the units for the constants simpler, we could set some of them arbitrarily to a value of 1. For example, physics will still work as well if you set the speed of light to be 1, the Gravitational Constant to be 1 and Planck's Constant to be 1. If you do this, the answers you get by solving the equations will not be in units that we recognise, but they will still be correct and meaningful.
He further points out that gravity is not a real force in the same sense that a centrifugal force is not real. It is useful to use it to describe the way the universe works from one point of view, but it is an emergent property of the distortion of space time rather that a force of the same type as magnetism or electro-static forces. Then he moves on to attack one of the favorite fallacies of many scientific writers, who claim that gravity is a very weak force compared with electrostatics. He does it like this.
'Fine tuners' take the example of a hydrogen atom to prove their point. They say that the gravitational attraction between a proton and an electron is negligible compared with the force arising from their electrical charge. For some reason they suggest that all natural forces really ought to be of comparable magnitude if they were the result of a natural origin, but in fact they are different by 39 orders of magnitude. (Heaven alone knows why they think this!)
Stenger argues that they have no justification for choosing a system containing a proton and an electron. A proton is not even a fundamental particle, after all. He suggests that these particles have not been chosen arbitrarily but just to prove a fallacy, and that if you used a quantity known as the Planck mass as your starting point the whole argument would fall apart. He argues that the Planck mass is the only non-arbitrary unit of mass. Whether that is a reasonable claim or not, it does at least undermine the assertion that gravity is a weak force.
Next time you fall over, try telling yourself how weak gravity is!
So you see, the whole topic of fine tuning is a battle of words and equations. There will be one more post on the subject soon.