realist-objection-to-van-fraassen
Van Fraassen on the division between scientific realism and anti-realism
Van Fraasen begins by giving different philosophers take on Scientific-realism and then gives his own formulation:
“Science aims to give us, in its theories, a literally true story of what the world is like; and acceptance of a scientific theory involves the belief that it is true. This is the correct statement of scientific realism”
In the first part of the definition, scientific realism claims that it is the aim of science to give us an accurate description of reality. Van Fraasen further clarifies (p. 8):
- the aim of science is not the be confused with the individual scientists’ motive
- the aim determines what counts as success in the enterprise; the aim may be pursued for any number of reasons
- there may be other aims of science
The second part of the definition touches on epistemology.
- tentative acceptance involves the tentative adoption of the belief that it is true.
Following this, he gives a statement for scientific-anti-realism =
“Accordingly, anti-realism is a position according to which the aim of science can well be served without giving such a literally true story, and acceptance of a theory may properly involve something less (or other) than belief that it is true.” (p. 9)
To demonstrate the distinction between Scientific-realism and scientific-anti-realism, he points out the difference in purposing a theory.
What does a scientist do then, according to these different positions? According to the realist, when someone proposes a theory. he is asserting it to be true. But according to the anti-realist, the proposer does not assert the theory to be true; he displays it, and claims certain virtues for it. (p. 10)
He asserts that the distinction he draws between realism and anti-realism “in so far as it pertains to acceptance, concerns only how much belief is involved therein.” (p. 12) The main point Van Fraassen is arguing is on the acceptance of a theory.
literally constructed language
Van Fraassen claims an important aspect of a literally true account is that language is to be literally constructed
- statements of science are statements capable of being true or false
- a literal construal can elaborate but no change logical relationships
- two theories which contradict each other but say the same thing are not literally constructed
This divides anti-realist into two types:
- science aims to be true, properly (but not literally) constructed
- language of science should be literally constructed but its theories need not to be true or good
The second type is what Van Fraassen’s constructive empiricism is. Insisting on a literal construal of the language of science is to rule out the construal of a theory as a metaphor or simile. But every scientific account which insists on a literal construal of the language of science is not a realist position.
Constructive Empiricism
Van Fraassen describes constructive empiricism as:
“Science aims to give us theories which are empirically adequate; and acceptance of a theory involves as belief onlv that it is empirically adequate” (p. 12)
This stands in contrast to Scientific-realism that Van Fraassen describes previously.
The constructive empiricist holds that science aims at truth about the observable aspects of the world but not aim at truth about unobservable aspects.
Empirical Adequacy
By empirically adequate, Van Fraassen means that
“a theory is empirically adequate exactly if what it says about the observable things and events in this world, is true — exactly if it ‘saves the phenomena’. A little more precisely: such a theory has at least one model that all the actual phenomena fit inside.”
By taking a theory to be empirically adequate, the constructive empiricist is simply saying that the phenomena we observe (and believe to exist) can exist within the structure the theory describes, without additionally being committed to saying that the unobservable parts of that structure are parts of the actual reality of the world.
In other words, accepting a theory implies believing that it is true with respect to observable phenomena, and not with unobservables. Science gives us epistemic access to the observable world but it does not give us a window into the unobservable. The leap between “electron theory works” and “electrons are real” is something that Van Fraassen believes we should not make.
Acceptance of a theory
Van Fraasen adds another component to acceptance than just belief in empirical adequacy. He is saying that acceptance in a theory is also a broader practical epistemic commitment that shapes how you engage with the world going forward.
“Acceptance of theories (whether full, tentative, to a degree, etc.) is a phenomenon of scientific activity which clearly involves more than belief … acceptance involves not only belief but a certain commitment” (p. 12)
Acceptance of a theory involves:
- belief = in empirical adequacy
- commitment = a practical, looking forward dedication to working within the theory’s framework
Since we can never have a fully completed theory, acceptance of a theory means that there is more than just belief, there is commitment to develop the theory forward. Van Fraasen says that by accepting a theory, a scientist commits himself to a certain research programme, and that that commitment means adopting that framework’s language and tools, explaining phenomena through that lens, etc. = ideas that come straight from Kuhn-on-paradigms.
Van Fraassen insists that all these commitments beyond simply believing that the theory is true are practical and methodological that can be made while remaining agnostic about whether the theory’s unobservable
Observable-Unobservable distinction
“X is observable to us if there are circumstances which are such that if X is present to us under those circumstances, then we observe it [with our unadided senses]” (p. 16)
He also makes the following clarifications (p. 15):
- the term “observable” classifies putative entities (entities that may or may not exist)
- e.g. a flying horse is observable, and the number seventeen is not
- there is supposed to be a correlate classification of human acts: an unaided act of perception is and observation
- e.g. calculating of mass from the deflection of its trajectory in a known force field is not an observation of mass
- there is a difference between observing (an entity) and observing that (something is the case)
There is a problem about where to draw the line between what is observable and what is unobservable.
Van Fraasen makes the case that moons of Jupiter seen from a telescope are observables while electrons seen in a cloud chamber are unobservables. This is from the fact that the moons of Jupiter can be seen by the unaided eye if astronauts got close to them, the same case is not possible for electrons. He gives the example that seeing vapor trails of a jet and the vapor trails of electrons in a cloud chamber:
“The theory says that if a charged particle traverses a chamber filled with saturated vapor, some atoms in the neighborhood of its path are ionized. If this vapor is decompressed, and hence becomes super-saturated, it condenses in droplets on the ions, thus marking the path of the particle. The resulting gray line is similar (physically as well as in appearance) to the vapor trail left in the sky when a jet passes. For a jet trail, if you would look ahead of the trail, you will see the jet causing the trail. However, in the case of the cloud chamber this response is not possible. So while the particle is detected by means of the cloud chamber, and the detection is based on observation, it is clearly not a case of the particle’s being observed.” (p.17)
Van-Fraassen defends epistemology based on the observable-unobservable distinction.
- Evidence obtained from our unaided senses is superior to evidence from aids to our sense (e.g. microscope)
- he admits that the distinction is vague
- you will have to draw the line at some point and there are a lot of defensible cases of where to draw the line
- relative to the an epistemic community (human beings)
What this distinction is getting at is that using aid to our senses means that we need to make inferences and assumptions based on the instrument. There is calibration and comparison needed to use these instruments and so the evidence obtained from those instruments would be more suspect than something we see without aid.
He agrees that we can manipulate the ions and we should use our theories and instruments to do so. We should trust our data but we shouldn’t infer that means that they are actually there.
Van-Fraassen want there to be strongest evidence.
If there’s all these ways to interact with these “unobservable”, why should we not infer that they are actually there? I see Hacking-on-scientific-realism “if we can spray them then they are real” as stronger argument than Van-Fraassen. Why should our direct access with our senses be a stronger case than interaction through our instruments.
Van-Fraassen against the no-miracles-argument
He argues that inference-to-the-best-explanation works for observables, but we shouldn’t apply it to unobservables.
His second argument =
“I would like to point out that science is a biological phenomenon, an activity by one kind of organism which facilitates its interaction with the environment. … [consider a mouse who runs from its enemy, the cat] …the Darwinist says: Do not ask why the mouse runs from its enemy. Species which did not cope with their natural enemies no longer exist. That is why there are only ones who do. … In just the same way, I claim that the success of current scientific theories is no miracle. It is not even surprising to the scientific (Darwinist) mind. For any scientific theory is born into a life of fierce competition, a jungle red in tooth and claw. Only the successful scientific theories survive—the ones which in fact latched on to actual regularities in nature.” (pp.39-40)
His argument is that it is not because our scientific theories are true, there is an evolutionary reason for our success. Our current theories are successful because we picked our theories because they gave us good predictions, not necessarily because our theories are describing reality.