Metaphysics vs Science? A dialogue with The A-Unicornist

Mike D, over at The A-Unicornist, and I have been engaging in a spirited discussion regarding the validity of metaphysical reasoning, which began as a discussion regarding the validity of the Scholastic concepts of actuality and potentiality (it began in the comment section here). Upon writing my most recent response to Mike, I felt that the length, as well as the topics covered in said response, deserved a post here on my blog. That being said, I also feel that Mike is one the most well-read and intelligent skeptics here on the blogosphere, and I believe that his perspective is founded upon well-thought out arguments. Therefore, I feel that a discussion such as the following is very fruitful and illuminating discourse. 

What follows (beginning with a quote from Mike) is my response to Mike's well articulated points:

It's trivially true that metaphysics are distinct from science – that one can't justify evidentialism with evidence, and so forth. All the empirical evidence in the world can't "disprove" idealism, and so forth.

I’m not really sure why you think this is “trivially true”. Is it only trivially true that biology and physics are distinct? If one’s epistemology asserts that method (a) is the only valid method for attaining knowledge about reality, then to admit of another method (b) to justify (a) would be to pull the rug out from that epistemology. This is exactly what happens to empiricism, and evidentialism as well.  

“However, consider that any metaphysical proposition is essentially a set of assumptions about what reality is.”

Not at all. You seem to think that metaphysicians simply wake up one morning and say “I’m going to postulate a concept called causation, let’s see how far I can go with it.” Metaphysicians begin with an observation of reality, and then derive their concepts. For example, a philosopher will see a billiard smash into another and, perhaps, abstract the concept of causation. Then, the philosopher will ask questions such as the following:

(1) Is this an example of event causation, or agent causation?

(2) Is causation simply the constant conjunction of events?

(3) Is causation transitive?

(4) Can causation be defined in more simplistic concepts, or is it irreducible and primitive?

Nothing in this endeavor is pure assumption. It is an abstraction of concepts from experience, followed by an inquiry into the nature and relations of these concepts. This is not something science can do, and it’s something that science relies on itself.

“So, unless we just want to engage in endless mental masturbation, metaphysical assumptions must be consistent with reality as we actually observe it.”

Maybe, or maybe not. It is arguable that there are metaphysical propositions so certain that no amount of empirical investigation can overturn. For example, we know that mathematics is based off of set theory which is based off of experience. (Just like the questions above are based on the concept of causation which has been abstracted from experience.) Some mathematics informs us of things we can be absolutely certain about, like 1+1=2. Now, what if we experienced a phenomenon such that every time we put two sticks together a third stick would spontaneously appear beside them? Would we then need to call into question our proposition that 1+1=2, and subsequently replace it with 1+1=3? Surely not.

“What I do know is that empiricism produces models of reality that reliably comport with independently verifiable observation. To paraphrase Stephen Hawking, science wins because it works. Empirical science has given us the ability to predict and manipulate the physical world.”

First, you seem to be pitting science and metaphysics against each other—Science wins because it works?--as if they were competing for a comprehensive view of reality. Science wins at describing the physical, metaphysics wins at describing the metaphysical, and that’s all there is to it—they are, contrary to what you say, complementary. The only out here is to claim that reality cannot be described by metaphysics. But this is, once again, self-refuting. You seem to want to assert that physics gives us as best and comprehensive a view of reality as we can obtain. But, to repeat ad nauseum, once you make a claim like that, you have ventured into metaphysics and ontology, and have (1) opened the door for metaphysical inquiry, and (2) put into question the very proposition that physics is our best lens into reality.

Second, of course science has given us the ability to predict and manipulate the physical world, that’s exactly what it was designed for. It was designed for pragmatic utility. But to claim that this allows us to declare science the victor over metaphysics is only to make a category mistake. Metaphysics is not in the game of utility, it is occupied with the fundamental structure of reality, and we have seen that, on pain of logical contradiction, science cannot take us this far.

“So when I'm presented with concepts like "potentiality" and "actuality", all I have to do is ask myself why I should believe they are descriptive of a fundamental reality, and not merely abstractions ascribed to the physical world by human minds. Is there any phenomenon, such as "change", that is either better explained or necessarily explained by potentiality and actuality? No.”

Personal incredulity is not enough to argue that concepts like act/potency are superfluous. The problem is that you’re trying to find the utility in utilizing these metaphysical concepts. And you think that since you can describe causation or change without reference to these concepts then they are unnecessary. But, you’re looking at it from the wrong perspective. It is not claimed that when describing change or causation one needs to use act/potency. Rather, it is claimed that the concepts of change and causation rely on these concepts in order to be intelligible. It must be true that the intelligibility of these concepts and concepts like them, of which I mentioned earlier, will not be illuminated by scientific inquiry. Science can say things like “event (a) exhibits causation,” but it cannot answer the question of what causation would need to entail for event (a) to participate in it.

“The laws of physics govern the interaction of objects in the physical universe, and the conservation of energy eliminates the need for a supernatural force to constantly intervene in or somehow govern the changes of energy and matter.”

The simple concepts of act/potency require no prima facie need for a supernatural force. By actuality one simply means the state whereby a substance is actual or existing, and by potentiality one means the potential realizations a substance can actualize. There is no need, at this level, for talk of supernatural forces. Act/potency are pure metaphysical concepts, and if one wants to utilize them for natural theology then we can determine whether this is valid or not, but the concepts themselves don’t necessitate such an endeavor.

“Potentiality and actuality simply add nothing useful whatsoever to our understanding of reality.”

You’re only begging the question here. As articulated above, they might not be necessary for an empirical description of reality, but they are quite necessary for a metaphysical description of reality. And to claim that the latter description is invalid is (1) self-refuting and (2) question-begging.

“The only reason you seem to assume their existence as fundamentally descriptive states of being is because Aquinas' argument from motion is meaningless drivel without that assumption.”

On the contrary, act/potency are metaphysical concepts just as foundational as identity, event, substance, composition etc. To claim that I only assume their existence for my own theological agenda is simply to beg the question.

“Occam's Razor tells us not to multiply assumptions beyond necessity. And I simply see no reason whatsoever to make the assumption that potentiality and actuality add any necessary descriptive value to our understanding of reality.”

You’re once again conflating the metaphysical with the physical. I concur that metaphysical concepts might not be necessary in describing events in physics—though I might not even go that far. But metaphysical concepts operate on a different plain than physical science.

Moreover, to claim that act/potency add no value to a description of reality is already to assume that reality can only be described in empirical terms. It is to beg the question in favor of empiricism. Act/potency surely add to metaphysical descriptions, and there is no logical way to deny the validity of metaphysical descriptions.