I don't think the presence of natural laws proves a lack of free will. Natural laws aren't like God, in that they impose on us rules of behavior from without. Nor are the things themselves reducible to merely the laws. The laws are our laws, stated in various languages, including mathematics, as predictive tools. In any given moment, with any given object of study, and with any given predictive formula, science assumes absolute knowledge of the object and its conditions. It does this because its necessary, and it produces very useful results from which we abstract and form various laws. But science never has absolute knowledge in any given context, it knows this, but doesn't consider it a fault but rather a necessity.
In this necessity of subjectivity, of human knowledge, lies freedom. Quantum mechanics recognizes this better now, as it gives more importance to the role of the observer in the predictive laws that result.
The analogy of humans to a computer doesn't really work, because the computer is a physical replication of the laws which were originally predictive abstractions from non-abstract things. I don't hear many scientists, and much less philosophers, arguing that natural laws prove absolute determinism, but rather the very fact that there are laws and that these laws are abstract and predictive in nature proves freedom.
I liked that...and it's so true...our "facts" are nothing more than the latest "best guess". More people need to realize this. Tomorrows "facts" will blow away yesterdays "facts".
Many people say the natural laws ARE God...because without them all being just right...we probably wouldn't be here. Supposedly some things a little lighter, a little heavier, too strong, not strong enough...and we probably wouldn't be here.
There IS evidence to lead down the path of "Intelligent Design"...who could deny it's POSSIBILITY. But it's hardly probable and for it to be "The God of Abraham"...or any other human God story...is HIGHLY unlikely.
The best answer though is...we're REALLY lucky everything worked out like it did.
@GMT I never said that you were arguing this point, I was merely reminded of the argument and was clarifying to anyone out there trying to use this to champion free will that it is a fallacy. Also, regardless of what my beliefs are, my brain (and everyone elses') convinces us that we have the ability to make decisions - this is fundamental and unavoidable. This is why the conclusion that there is no free will is somewhat meaningless in all practicality. Also it is impossible to not be a fatalist if you champion a 4 dimensionalist view of time.
@ibjamming: Just because we second guess and are subject to hormones doesn't mean we make decisions. These processes are governed by physical matter (neurotransmitters) that kick into action after a stimuli is received. For example, our eyes receive input data in the form of light. We see the weed sitting on the table. The signal is then travels through sensory neurons to the brain and the brain takes this information and does an analysis based on our genetics and past experience. It then churns out an appropriate response. This isn't governed by a mystical essence of "you" - it is merely the playing out of neurochemistry.
@sac beh: I never said that scientists use the presence of natural laws to prove determinism. It is just an introductory argument to get people thinking. If one is not a dualist, than what we are is purely physical. THere is no spirit. If you hold the no-spirit view than you also believe that the brain is what constitutes the mind. The brain is physical and we as agents don't have control over physical matter/laws. I don't see how a law would imply freedom in any sense of the word; it implies the exact opposite. Laws are rigid, that is why they are laws. Quantum mechanics, i.e. wheeler's delayed choice and the double slit experiment, does not prove that observers have free will (I am not saying this is what you are arguing) it just says that in order for there to be a reality, there must be an observer. Until particles are observed, they exist in a super-state of many potential outcomes.
You're assuming that everyone's brain is wired the same and responds the same. I can see your point...and I agree, we're nothing more than electrical and chemical connections...but I think the outcome is more random...like a pachinko machine. You can put the ball in the same place but the outcome isn't fixed. I think the randomness...maybe caused by quantum effects...play a role. That's the second guessing part...the going over many scenarios and choosing the "best", which changes all the time. Besides, two people don't make the same decision given the same circumstances.
I was just sitting here replying and remembered a virus or a parasite that changes the behavior of a snail...it MAKES the snail do something that ONLY infected snails do...which results in the snails own death. It seems to "reprogram" the snail causing it to behave abnormally. I think it climbs up and out into the open for a bird to eat it...when most snails stay hidden...something like that.
You MAY be onto something... Maybe we ARE being controlled...maybe our programming IS already set? Maybe viruses/parasites affect human behavior too? Other animals?
The world is pretty amazing...full of wonders and questions.