I've recently been following the debate between proponents of evolutionary theory and those of intelligent design. It seems to me that the crux of their disagreement is around the existence of chance. Both parties seem (more or less) to agree on the mechanism (incremental development of species over time through selection of beneficial traits); but evolutionary theory states that these changes are random, the product of chance uninfluenced by God, while ID seems to think that God directs what we think of as chance, in effect denying the existence of randomness. But the question arises: if God doesn't influence chance, if true randomness occurs in nature, then what *does* God influence? Can a belief in evolutionary theory, or any theory that relies on chance occurrence, be compatible with a belief in God?

If irreducibly chancy processes occur in nature, God could be responsible for setting up laws of nature that specify those chances. Here is what I mean. Even irreducibly chancy processes are governed by laws. For instance, a given radioactive isotope has a given half-life L. (That is to say, for any given atom of that isotope existing at time t, there is a 50% chance of its decaying before time t+L.) That atoms of this isotope have half-life L is fixed by some laws of nature. Some philosophers believe that God is responsible for installing those laws. In this way, they believe, God arranged things so as to make it possible (even probable, perhaps) for intelligent creatures to evolve. So the laws of nature are something that God could "influence" even if God does not determine the outcomes of chance processes. Needless to say, it is far from obvious that the fundamental laws of nature are best explained by God. Some philosophers would contend that the fundamental laws of nature are brute facts...

Why is the Big Bang theory the most widely accepted theory of the creation of the universe?

The Big Bang theory nicely explains the expansion of the universe (discovered by Hubble in the 1920's). Obviously, that the universe is expanding suggests that it was a good deal smaller in the past. Likewise, the Big Bang theory nicely explains the cosmic microwave background radiation (detected by Penzias and Wilson in the 1960's, and predicted by Wilkinson and Dicke before that). This pervasive, pretty uniform, low-temperature radiation suggests that the universe was considerably hotter in the distant past. The rival "steady state" model of the universe has difficulty explaining these observations. However, the "Big Bang theory" is no longer a single theory. Various alternative Big Bang models have been developed (such as the "inflationary" Big Bang theory) to account for additional facts that have been discovered (such as the value of omega, the ratio of the universe's total kinetic energy of expansion to its gravitational potential self-energy, which tends to slow down the expansion). At the...

Where can I read something about the difference between explanation and justification? How would you put this difference in a few words?

A scientific explanation specifies the reason *why* some fact is the case or (or the reason why some event came about). A justification specifies someone's good reason for believing in the truth of some claim. For example, my justification for believing that the dinosaurs went extinct is that I have seen no dinosaurs around, and I have never heard any reports of living dinosaurs, but I have seen all of those fossils, and scientists whom I trust say that they have good evidence that dinosaurs once roamed the earth. But that's not the reason why the dinosaurs went extinct. The explanation (according to our best current theories) involved a large object crashing into the earth. Notice that my justification for believing that the dinosaurs went extinct does not concern my knowledge of the reason why they went extinct. Notice also that I could be justified in believing in some claim even if, as a matter of fact, the claim is false. A physician, for instance, might be justified in believing...

Say we could speed up matter and go further into time. I went and I saw my future self, no interaction, and I noticed that I had a finger missing or some dramatic change in my body since my present self. Could I dedicate my life to keeping my finger safe, or will it happen anyway?

I agree with Professor George's answer, but I would like to add one thing. Suppose you are a professor of English. You take a time-machine trip into the future and learn from a reliable source that you died in dramatic fashion: in the midst of teaching a Shakespeare class. You tend to get very excited while teaching Shakespeare, and you died from cardiac arrest while giving a spirited lecture. However, you do not learn anything about the date of your death. Then you travel back to 2005 and continue your life. When your department chair asks you what you would like to teach next year, it would be perfectly rational for you to say, "Anything but Shakespeare." By not teaching Shakespeare, you cannot change the future from what it will be. (Apparently, despite your determination never to teach Shakespeare again, you end up doing so, somehow, and die in the midst of it.) But by not teaching your Shakespeare class next year, you can make it true that you lived a longer life. It is no different from your...

According to statistics one in five people experiences depression. If depression is so common, how do we know it is an illness and not just a normal part of being human?

That is an excellent question. The distinction between health and illness is tremendously controversial. Some philosophers believe that the difference is fixed entirely by various facts about the natural world. These philosophers might point out that insofar as depression arises from the production of certain extreme quantities of some neurotransmitter or from some particular gene, which ultimately inhibits or prevents certain cells from carrying out their basic life functions (e.g., from employing a certain metabolic pathway to derive energy), then depression has a biochemical basis. On this view, that depression is common does not change the fact that it involves the malfunctioning of some part of the body, where "malfunctioning" can be cashed out in exclusively naturalistic terms. (But what, then, does it mean for a part of the body to function properly? What determines the body part's biological function? That is a controversial question.) Other philosophers disagree. They believe that the...

It is often said that the the phrase "before the BIG BANG" is meaningless because the BB is the beginning of things, time included. My question is "Is the phrase truly meaningless?" I take it as axiomatic that a real event occurs only if it were already a possible event. If the BB did indeed happen then it must have been the fruition of an antecedent possibility - some entity 'before the BB'. ERIC STOCKTON, ORKNEY UK

I, too, have heard it said that the phrase "before the Big Bang" is meaningless. One analogy I have heard drawn is between the phrase "before the Big Bang" and the phrase "more northerly than 90 degrees north latitude". Just as the latter phrase refers to no real location on Earth, so the former phrase is supposed to refer to no real location in time. According to cosmology's current picture of the Big Bang (as I understand it), the analogy is apt. (Of course, that doesn't rule out the possibility of further scientific developments resulting in corrections to the theory of the Big Bang.) It may seem unsatisfying to you that a scientific theory could just rule out as "meaningless" a notion that seems pretheoretically to be perfectly sensible. Intuitively, it seems like the question "What happened before the Big Bang?" ought to have an ordinary answer, rather than a cop-out answer like "There is no such time." However, the history of science is full of examples of questions that were once thought to...

If we are part of a 4-D spacetime, why do we experience past and present?

What we experience depends on what information about the world we receive and when we receive it. We receive information about the world through our senses, as when a ray of light arrives in one of our eyes from an event that occurred sometime in the past. (That light ray may have been launched by an event that occurred just a few millimicroseconds ago, or it might have come instead from an event in the very distant past, as when a ray of light emitted by stars many years ago enter our eyes as we look up at the sky at night. If the star is 100 light years away, then that ray of light was emitted 100 years ago.) Since we do not receive rays of light today from events that have not happened yet, we do not experience the future (yet!). Now light travels very quickly, as you know. The various rays of light that are arriving in my eyes right now, having previously bounced off of various objects in the room I'm in, all left those objects at very nearly the same moment. So those rays of light give...

After a discussion about time travel, I asked my high school science teacher, “How can we be sure time even exists? How do we know it’s a tangible thing that can be traveled through?” His simple reply was to say that time can be measured. Therefore, it exists. That answer was never enough. As I’ve grown older, I still believe that time doesn’t exist, because all it is, is a term used to describe the interaction between matter. As matter interacts, the physical world changes, thereby creating one’s perception of ‘time’. The more gravity one has, the slower matter interacts and the inverse. One can’t go back in time, because one can’t rewind all the infinite physical changes that have taken place. However, one can speed up the interactions. So, I pose you the same question. How can we be sure time exists?

Newton proposed that there is "absolute time", over and above the motions of clocks and pendulums and celestial bodies that (to some degree of accuracy) measure absolute time. Newton did so in the context of a scientific theory that aimed to account for some of our observations of the motions of material bodies. The tremendous success of his theory counted as good evidence for the existence of absolute time. Roughly the same situation exists today, except that our best current theories of how and why bodies do what they do fail to use Newtonian absolute time. Those theories (roughly, quantum mechanics and relativity theory) use other notions of time -- indeed, notions that are difficult to reconcile. Still, whatever evidence we have that time exists comes primarily from evidence for our best scientific theories, which use various concepts of time to characterize the universe. Now those theories might be mistaken, or the evidence for their accuracy might not constitute very strong evidence for what...

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