I. A Standard View

 

a) There is a distinction between observable things and theoretical things.

b) There is a corresponding distinction between observation and theoretical words.

c) And a corresponding between observation/theoretical statements, depending upon which kinds of terms are involved.

d) Observations play a number of important roles: i) justifying theories; ii) observations provide a theory neutral way of comparing theories. Suppose that there are two theories about something. We want to check which is true. If they have different observable implications, then we can check; iii) give meaning to the theoretical terms, through the bridge laws.

 

II. Complications

 

a) Distinction (a) above, and thus the others, gets murkier when we take into account the use of instruments to observe things. Let’s assume that we do observe things when we use microscopes and telescopes.

b) The status of a thing as a theoretical entity may change over time, depending upon what instruments are available. Neptune?

c) Also a thing may be “theoretical” for one observer and “observable” for another. The burglar in the basement is a “theoretical entity” for me (inferred from the noises I hear), but not for his accomplice.

d) One object can have observable and non-observable properties. I can tell by observation that you are a human being, but (let’s say) not that you are a product of evolution. The latter is a theoretical property of you.

 

So maybe the right way to think about things depends upon this basic idea:

 

Property P is an observable property of object X for observer S at time T iff at T, S is able to determine by observation (as opposed to theoretical inference) whether or not X has P.

 

The key idea is that there is a difference between what we can determine by observation as opposed to by theoretical inference.

 

III. Hanson’s Objections

 

One way to think about Hanson’s article is that it shows that there are puzzles about the distinction just described. He gives several examples of people looking at the same thing, but there is a temptation to say that they see different things.(p. 340) And it’s not that their eyesight differs. To use a simpler example, he gives the Kepler/Brahe example. What’s his answer to his question, “Do they see the same thing?”

 

He says that there are reasons for both answers. In favor of “yes”: identical retinal images. (340-1) Blind people can’t see, sighted people can. (How does this help?) But then he says that those who think this answers his question speak carelessly. “Seeing the sun is not seeing retinal pictures of the sun.” Right. Then he mentions drunk, distracted, etc. people and concludes that “seeing is an experience.” His point: we should not conclude from the fact that they have the same retinal image that they see the same thing. They may fail to have the same visual experience.

 

Then he says that they do see the same physical object. Namely, the sun. They are both “visually aware” of the sun. This seems to be a clear cut assertion of a “yes” answer to his question.

 

On p. 342, middle, he seems to repeat this. He says that their visual experiences are alike. Earlier on this page he says that each has a similar “sense datum”. Thus, they see the same thing. Again, this seems to be a clear “yes”.

 

He then suggests that they just interpret what they see differently. See last ¶ on p. 342. Here is a detail about understanding him that is important: he here summarizes by rejecting the retinal image argument for “yes”. He then mentions the “(i) same experience, so (ii) see the same thing, but (iii) different interpretation” view, and he says that there is a problem. But it is not yet clear where the problem with that view is - which is wrong, (i), (ii), or (iii).

 

But: figure reversal cases are not cases in which one sees the same thing and then interprets the thing differently. I think that he’s thinking that interpretation is a kind of conscious process of figuring out what something is, and we do not do this in the figure reversal cases. And, he says, same goes in the sun case. And for lots of other cases. His idea is that the “theory” is in the seeing in the first place, not a separate interpretative act. The same goes in several other examples, such as fig. 2 on p. 345 and the Arabic sentence mentioned on the top of p. 346. So, in this sense they see different things.

 

p. 347, near the bottom, there is a good summary. The conclusion is that there are several senses of “see”.

 

D1) X and Y see₁ the same thing =df. X and Y have visual experiences of the same thing

D2) X and Y see₂ the same thing =df. X and Y have similar visual experiences of the same thing

D3) X and Y see₃ the same thing =df. X and Y have similar visual experiences of the same thing and believe immediately the same information about that thing.

 

In the D1 sense and the D2 sense, the answer to his original question is “yes”. In the D3 sense, the answer is “no”.

 

A distinction that may help us to clarify things. Distinguish:

1) S sees X [Where S is an observer and X is an object or event.]
2) S sees that p [Where S is an observer and p is a proposition about the world around S.]

Apply this to the case of Kepler/Brahe. Or, better, apply it to the case on p. 345. Or apply it to a case in which an expert and a novice are looking at trees - one sees that there is a bristlecone pin, the other sees that there is a tree with needle like leaves. Conclusion: the objects one sees do not depend upon background knowledge, etc. But the propositions one sees to be true, seeing that, does depend upon background information. Some of this background information may be theoretical.

 

Hanson thinks that this is important because much of what we call observation in science involves claims in the (D3) sense. But then our background theories are affecting our observations. They are not “pure”.

 

Comments on assignment:

 

1) A lot of people said that his answer to the questions was “Yes and no”. He surely does say that, and I thought that a good response would make that point. But this needs explanation. How could that be? One idea: there are considerations in favor and there are considerations against. But this does not support the answer. Instead, it supports the view that the evidence is mixed and, perhaps, the answer is unclear. Analogy: suppose you are asked whether there has ever been life on Mars. You might say that the evidence is mixed. But this does not support a “Yes and no” response. That makes no sense.

 

A better idea, as just explained: ambiguity. Analogy: suppose an author is holding a book. Someone asks, “Is that your book?” The question can mean: “Is that a book you wrote?” or “Is that a book you own?” The answer to one might be “yes” and the other “no”. The same idea in the reading. He thinks that there are multiple meanings of “see”. According to one, you see something if it is at the other end of the causal chain leading to your visual experience (and maybe the image is alike). The two do see the same thing in this sense. The other meaning is not spelled out very clearly in the article, but it is suggested by (D3). Quite a few people gave the “yes and no” response, but didn’t explain it very clearly, just mentioning competing considerations, but not ambiguity.

 

2) Some said that his view was that they did not see the same thing. That’s ok, provided it was well explained. He does sometimes seem to say that the real or central or main use of “see” is the one that supports the “no” answer.

 

3) A lot of people said things along the lines of “seeing involves interpretation.” Then they quoted the passage from the bottom of p. 342. But, as noted, he goes on to argue against this.