Wednesday, October 24, 2007

Van Fraassen's Manifest Image

I had a thought about how to motivate van Fraassen's constructive empiricism (the view that we need only accept theories as empirically adequate, that is, believe what they say about observables and be agnostic about what they say about the unobservables) since anti-realist views can seem at times, unmotivated. The thought I had was that he is responding to Sellars's Philosophy and the Scientific Image of Man. (Apologies for poor Sellars reconstruction.) In that essay, Sellars contrasts two images of man, the manifest and scientific images. The manifest one is, roughly, the commonsense conception of ourselves and the world. The scientific image is that which contemporary science gives us. I think it is roughly the difference Eddington finds between the everyday idea of tables and chairs and the view of them as composed mostly of empty space and composed of small, small particles and fields, etc. Sellars thinks that one important job of philosophy is to spell out the relation between the images. In the end, he says that they don't need to be reconciled but that the manifest image needs to be joined to it. Sellars is also a realist of a rather extreme kind. He was also van Fraassen's teacher at Pitt.

Now, my crazy idea is that van Fraassen's constructive empiricism is an attempt to go the other way. It is an attempt incorporate the scientific image into the manifest. The manifest image seems to roughly correspond to the sort of thing that van Fraassen views as observable. Especially when viewed through empiricist lenses, the macroscopic level at which we normally find ourselves lends itself to being viewed as the world of the manifest image. Of course, van Fraassen doesn't talk much about intentions and norms that Sellars's manifest image also concerns itself with. Putting that aside for now, if one is agnostic about everything that is not observable, in van Fraassen's sense, then one is agnostic about the traditional way of understanding the scientific image. Eddington gets just the manifest table. Constructive empiricism says to be agnostic about the scientific table. Everything science says about the observable is incorporated into our beliefs about the world of the manifest image. This seems like it is one way of cashing out the relation between the relation between the two images of man. The scientific image helps us to understand the manifest image, but we need only believe in the world of the manifest image.

I floated this in my philosophy of science class today. A couple of good points were raised against it. One is that apart from the title, van Fraassen doesn't really mention the Sellars piece. Another is that what I have been calling the manifest image in van Fraassen's book is somewhat different than the manifest image in Sellars's essay. This is true, but it doesn't seem that far from what you'd get if you took Sellars's manifest image and tried to cast it in an empiricist vein. Depending how exactly observable gets spelled out in the end, this might not be tenable at all. I think that if the idea of observable is constrained to the roughly medium-sized macroscopic things and processes, then it is a possibility.

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