Examine these statements:

1. If we treat a single human brain cell as an eletrical device, we can run tests on it and figure out how it works. We can map out exactly how it reacts to various levels and types of input. Using the fundamental laws of physics and electromagnetism to understand the cell, we will be able to predict with certainty how this brain cell will react to an input -- given the state of the brain cell at time t, we can predict what's going to happen at time t+1.

2. If we study two brain cells and then "connect" them together as components in a "circuit," we will be able to predict with certainty how this simple circuit will behave.

3. If we incrementally add brain cells to our "circuit" one-by-one, we will start producing a more complex, but still readily understandable circuit. A "circuit" made of four components is somewhat more complex than a circuit made from two components, but its behavior can still be predicted. Likewise for eight, 20, 500, or a million components.

4. Eventually, if we continue adding brain cells to our circuit, we can construct a "circuit" that is identical to a human brain with N cells in it. And as difficult as it might sound, we should be able to painstakingly map out the electrical operation of such a complex "circuit" in the same manner that we map out the operation of a circuit with N-1 components in it -- if we know the state of all the circuit components at time t, we can precisely predict what's going to happen at time t+1.

5. At this point, we have essentially reduced the operation of a human brain to that of a giant, complex electric circuit -- the thoughts, perceptions, memories, and emotions generated by this brain are really no more than complex electrical signals carried on an intricate system of circuitry. And we can exactly and precisely predict what will happen in this giant brain-circuit given its state at any time.

6. Now, if we can conceive of fully understanding and predicting the way the human brain works, then we have come to a Deterministic view of human life -- meaning that the state of our brains (and thus our thoughts and actions) at any time t are precisely and deterministically derived from whatever the state of our brains was at time t-1. By extension of this same logic, the state of our brains at time t-1 was determined by the state at time t-2, which was ultimately determined by the state of our brains at the moment they came into existence: time = 0.

7. If you buy this logic, then you must believe that everything that we have done, are doing, and will ever do flows logically and unstoppably from the very moment of our existence -- nothing you do or think can possibly stop this chain of events. Free will is thus an illusion; you may think that you are going to do something random and wholly unexpected at any moment, when in fact, your every thought and action is a deterministic outcome of whatever was happening in the previous moment.

8. What's more, if the ideas of free will and randomness can be discounted, then everyone and everything around us, and indeed the entire Universe, behaves as one gigantic, super-complex, deterministic system. The physical laws that govern the interactions and connections between every object in this Universe may be subtle in their operation, but if we were able to comprehend the state of the Universe and all its laws, then we would be able to predict the state of the Universe at any time from 0 to Infinity. All of the past, present, and future is thus, in theory, calculable -- there are no random or unknowable events.

All of this is not to say that I think we are entirely Deterministic beings, for there are some definite logical flaws in the above statements. For one, if the state of the Universe at time t is dependant on the state at time t-1, then where did the state at time = 0 come from? And from a purely anecdotal standpoint, why do we feel like we have control and free will? If we cannot detect any evidence of over-riding determinism in our own thoughts, and if all our experience tells us that we have free will, then isn't that enough to satisfy the requirements of free will? E.g., if all appearances indicate that we have free will, and if all we can see are appearances, then that would seem like solid evidence of free will.

The best argument I have heard, to date, against the idea of determinism (and in support of free will) is this:

1. The "brain cells" discussed in the statements above are nothing more than neurons. Neurons are single cells that have very fine off-shoots called axons and dendrites. These axons and dendrites are responsible for carrying the electrical impulses that make up nerve signals.

2. Nerve impulses are passed from one neuron to another one at junctions called synapses. Synapses are the area where the axons of one neuron meet the dendrites of another neuron.

3. The physical conduction of an electrical signal from one neuron to another takes place through electro-chemcial reactions at the synapse. Specifically, electrically charged ions move from the axons of one nerve cell to the dendrites of other nerve cells.

4. These synaptic reactions take place very quickly, in an exceedingly small space. Moreover, the density of axons and dendrites in synaptic connections is very, very high -- much more dense than electrical circuitry on an advanced silicon semiconductor chip (computer chip).

5. The fact that axons and dendrites are so tightly packed into synapses means that our biological "circuitry" is not predictable in the same way that computer circuitry is predictable. This is because quantum effects (e.g. "tunneling") can affect the movement of electrons. In computers, circuits are made up of metal conductors on silicon chips. The lines of metal conductors on computer chips are designed so that they are spaced far enough apart to prevent quantum effects from disrupting the predictable operation of the circuit. That is to say, if we really packed the metal lines in a computer chip very close together, then quantum effects might occasionally make an electron jump randomly from one line to another one. This, of course, would be horrible for a computer because then it would give us random and unpredictable output. But the axons and dendrites that are in our brians are packed in together so closely that quantum effects can and do produce random and unpredictable output.

6. The ultimate "output" of the synapses in our brains is electrical patterns that we call "thoughts" or "emotions" or "memories" or any of the other stuff tha we know goes on in our heads. The things going on in our heads ultimately drive actions and behavior.

7. Thus, because the connections between neurons in our brains are fundamentally un-reliable, the activity of our brians is not completely deterministic. The randomness that is introduced by this non-determinism is what we call "free-will."

This type of argument for free-will only supports a weak form of free-will in that we do not do whatever we "want" -- rather, we come up with random thoughts and actions, and can claim them to be of "free-will" post-hoc. A strong free-will argument would show that individuals have some purpose and/or goals that guide their thoughts and actions, so that behavior is not just random, but actually is guided by meaningful human agency.

In any case, the concept of Determinism can be discussed in many, many different contexts, ranging from artificial intelligence to religion to consciousness to morality. That's why it's one of my favorite discussion topics!