This article (by a biologist) does a good job of rejecting the popular notion (known as scientism) that science can replace philosophy.
Scientism wrong on metaphysics:
The main fault of these arguments lies in their failure to distinguish between necessary and contingent being. A contingent being is one that might or might not exist, and thus might or might not have certain properties. In the context of modern quantum physics, or population genetics, one might even assign probability values to the existence or non-existence of some contingent being. But a necessary being is one that must exist, and whose properties could not be other than they are.
Multiverse theorists are simply saying that our universe and its laws have merely contingent being, and that other universes are conceivable and so also may exist, albeit contingently. The idea of the contingent nature of our universe may cut against the grain of modern materialism, and so seem novel to many physicists and philosophers, but it is not in fact new. Thomas Aquinas, for example, began the third of his famous five proofs of the existence of God (a being “necessary in itself”) with the observation of contingent being (“we find among things certain ones that might or might not be”). Whether or not one is convinced by Aquinas, it should be clear that the “discovery” that our universe is a contingent event among other contingent events is perfectly consistent with his argument.
Writers like Hawking, Mlodinow, and Smolin, however, use the contingent nature of our universe and its laws to argue for a very different conclusion from that of Aquinas — namely, that some contingent universe (whether or not it turned out to be our own) must have come into being, without the existence of any necessary being. Here again probability is essential to the argument: While any universe with a particular set of laws may be very improbable, with enough universes out there it becomes highly probable. This is the same principle behind the fact that, when I toss a coin, even though there is some probability that I will get heads and some probability that I will get tails, it is certain that I will get heads or tails. Similarly, modern theorists imply, the multiverse has necessary being even though any given universe does not.
The problem with this argument is that certainty in the sense of probability is not the same thing as necessary being: If I toss a coin, it is certain that I will get heads or tails, but that outcome depends on my tossing the coin, which I may not necessarily do. Likewise, any particular universe may follow from the existence of a multiverse, but the existence of the multiverse remains to be explained. In particular, the universe-generating process assumed by some multiverse theories is itself contingent because it depends on the action of laws assumed by the theory. The latter might be called meta-laws, since they form the basis for the origin of the individual universes, each with its own individual set of laws. So what determines the meta-laws? Either we must introduce meta-meta-laws, and so on in infinite regression, or we must hold that the meta-laws themselves are necessary — and so we have in effect just changed our understanding of what the fundamental universe is to one that contains many universes. In that case, we are still left without ultimate explanations as to why that universe exists or has the characteristics it does.
When it comes to such metaphysical questions, science and scientific speculation may offer much in fleshing out details, but they have so far failed to offer any explanations that are fundamentally novel to philosophy — much less have they supplanted it entirely.
Scientism wrong on Epistemology:
Natural selection can explain much about why species are the way they are, but it does not necessarily offer a specific explanation for human intellectual powers, much less any sort of basis for confidence in the reliability of science.
What van Fraassen, Quine, and these other thinkers are appealing to is a kind of popularized and misapplied Darwinism that bears little relationship to how evolution really operates, yet that appears in popular writings of all sorts — and even, as I have discovered in my own work as an evolutionary biologist, in the peer-reviewed literature. To speak of a “Darwinian” process of selection among culturally transmitted ideas, whether scientific theories or memes, is at best only a loose analogy with highly misleading implications. It easily becomes an interpretive blank check, permitting speculation that seems to explain any describable human trait. Moreover, even in the strongest possible interpretation of these arguments, at best they help a little in explaining why we human beings are capable of comprehending the universe — but they still say nothing about why the universe itself is comprehensible.
Scientism wrong on ethics:
Under Harris’s ethical framework, the central criteria for judging if a behavior is moral is whether or not it contributes to the “well-being of conscious creatures.” Harris’s ideas have all of the problems that have plagued utilitarian philosophy from the beginning. As utilitarians have for some time, Harris purports to challenge the fact-value distinction, or rather, to sidestep the tricky question of values entirely by just focusing on facts. But, as has also been true of utilitarians for some time, this move ends up being a way to advance certain values over others without arguing for them, and to leave large questions about those values unresolved.
Harris does not, for example, address the time-bound nature of such evaluations: Do we consider only the well-being of creatures that are conscious at the precise moment of our analysis? If yes, why should we accept such a bias? What of creatures that are going to possess consciousness in the near future — or would without human intervention — such as human embryos, whose destruction Harris staunchly advocates for the purposes of stem cell research? What of comatose patients, whose consciousness, and prospects for future consciousness, are uncertain? Harris might respond that he is only concerned with the well-being of creatures now experiencing consciousness, not any potentially future conscious creatures. But if so, should he not, for example, advocate expending all of the earth’s nonrenewable resources in one big here-and-now blowout, enhancing the physical well-being of those now living, and let future generations be damned? Yet Harris claims to be a conservationist. Surely the best justification for resource conservation on the basis of his ethics would be that it enhances the well-being of future generations of conscious creatures. If those potential future creatures merit our consideration, why should we not extend the same consideration to creatures already in existence, whose potential future involves consciousness?
Moreover, the factual analysis Harris touts cannot nearly bear the weight of the ethical inquiry he claims it does. Harris argues that the question of what factors contribute to the “well-being of conscious creatures” is a factual one, and furthermore that science can provide insights into these factors, and someday perhaps even give definitive accounts of them. Harris himself has been involved in research that examines the brain states of human subjects engaged in a variety of tasks. Although there has been much overhyping of brain imaging, the limitations of this sort of research are becoming increasingly obvious. Even on their own terms, these studies at best provide evidence of correlation, not of causation, and of correlations mixed in with the unfathomably complex interplay of cause and effect that are the brain and the mind. These studies inherently claim to get around the problems of understanding subjective consciousness by examining the brain, but the basic unlikeness of first-person qualitative experience and third-person events that can be examined by anyone places fundamental limits on the usual reductive techniques of empirical science.
We might still grant Harris’s assumption that neuroscience will someday reveal, in great biochemical and physiological detail, a set of factors highly associated with a sense of well-being. Even so, there would be limitations on how much this knowledge would advance human happiness. For comparison, we know a quite a lot about the physiology of digestion, and we are able to describe in great detail the physiological differences between the digestive system of a person who is starving and that of a person who has just eaten a satisfying and nutritionally balanced meal. But this knowledge contributes little to solving world hunger. This is because the factor that makes the difference — that is, the meal — comes from outside the person. Unless the factors causing our well-being come primarily from within, and are totally independent of what happens in our environment, Harris’s project will not be the key to achieving universal well-being.
The persistence of philosophy
The positivist tradition in philosophy gave scientism a strong impetus by denying validity to any area of human knowledge outside of natural science. More recent advocates of scientism have taken the ironic but logical next step of denying any useful role for philosophy whatsoever, even the subservient philosophy of the positivist sort. But the last laugh, it seems, remains with the philosophers — for the advocates of scientism reveal conceptual confusions that are obvious upon philosophical reflection. Rather than rendering philosophy obsolete, scientism is setting the stage for its much-needed revival.
Advocates of scientism today claim the sole mantle of rationality, frequently equating science with reason itself. Yet it seems the very antithesis of reason to insist that science can do what it cannot, or even that it has done what it demonstrably has not. As a scientist, I would never deny that scientific discoveries can have important implications for metaphysics, epistemology, and ethics, and that everyone interested in these topics needs to be scientifically literate. But the claim that science and science alone can answer longstanding questions in these fields gives rise to countless problems.
In contrast to reason, a defining characteristic of superstition is the stubborn insistence that something — a fetish, an amulet, a pack of Tarot cards — has powers which no evidence supports. From this perspective, scientism appears to have as much in common with superstition as it does with properly conducted scientific research. Scientism claims that science has already resolved questions that are inherently beyond its ability to answer.
…One longs for a new Enlightenment to puncture the pretensions of this latest superstition.