|Propensities: propensities are an interpretation of probability that gives it an objectivist orientation. The expression denotes the tendency in an experimental setup to favor future events. The term was proposed by K. Popper (K. Popper, The Propensity Interpretation of Probability, In British Journal for the Philosophy of Science. X (37), 1959). See also probability, subjective probability, objective probability, bayesianism, quantum mechanics._____________Annotation: The above characterizations of concepts are neither definitions nor exhausting presentations of problems related to them. Instead, they are intended to give a short introduction to the contributions below. – Lexicon of Arguments. |
Functional Explanation/Forward-looking theory/function/Bigelow/Pargetter:
1. Aetiological theory/Bigelow/Pargetter:
For example, suppose that a pattern usually has a certain effect and is the result of natural selection. Then the aetiological theory says, that it is now a function of this pattern.
In the past, there must have been a relevant effect in a sufficient number of cases.
N.B.: the corresponding situations are not randomly chosen situations, but situations where the effect was appropriate. In these situations, it contributes to survival.
Propensity/Survival/Bigelow/Pargetter: although probability laws allow for a long series of coincidences, this is very unlikely. Normally, there will be a propensity towards the survival of the individual.
Function/Bigelow/Pargetter: if there are only a few coincidences, we certainly do not speak of function.
Aetiological theory/Bigelow/Pargetter: we interpret it in a way so it attributes the function for the whole time, even before it contributed to survival! At that time, it contributed to a propensity.
Environment: this too must be relativized for the environment. If this suddenly changes, there may be ambiguities of adaptation.
Function/Bigelow/Pargetter: Functions can be described as components of an organism in descending hierarchy of complexity. For example, body parts, but also cells have functions.
Propensity theory/Bigelow/Pargetter: according to it, the functions are therefore relational properties.
And they are dispositional. This is true even if the individual does not survive or is never in his normal environment.
Explanation/Bigelow/Pargetter: the functions interpreted (like that as propensities) explain survival by causal information, as a why-explanation.
Propensity Theory/Artefacts/Bigelow/Pargetter: can it be applied to artifacts as well as to biological patterns? It can be part of an overarching theory, but with artifacts there is again the problem of looking back (see above).
Solution/Bigelow/Pargetter: Thesis: we propose a theory of propensity for selection as a forward-looking theory for biological patterns and artifacts.
This means that all functions, be they biological or artifacts, have something in common.
Function/fitness/causal explanation/propensity theory/Bigelow/Pargetter: it is possible that an organism may not survive, even though it has developed a survival function. But if it survives, it is because of this function.
VsPropensity theory/Bigelow/Pargetter: For example, a structure does not serve any purpose at all, suppose its environment changes, and suddenly its functions serve survival. Then our theory of propensity would have to say that the structure has a function lately. For example, suppose one could say that heart tones have the function of alerting doctors. But only in this century, that seems wrong.
Aetiological theory: says that heart tones have no such function because they are not designed for it.
Bigelow/Pargetter: nevertheless the reason why we want to deny heart tones a function is not that they have no evolutionary history of the desired kind...
...but because the heart tones have an inevitable connection with the function of blood pumping. The heartbeat does nott produce any propensity for survival.
This corresponds to examples of functions that existed in the past, but have now lost their function:
VsPropensity Theory/Bigelow/Pargetter: this assumes that the pattern has no function.
Aetiological theory: assumes that it has a function, no matter what it was used for and what it was designed for.
Propensity Theory/Bigelow/Pargetter: generally gives better explanations. We can say that this function used to exist in the past, but unfortunately it became harmful to the individual.
Explanation/Bigelow/Pargetter: a propensity can play an explanatory causal role, while the fact that something has a historical origin does not matter. This shows us that the propensity theory has such strong advantages that it seems to be justified to argue away counterexamples.
Paul GriffithsVsPropensity Theory/Bigelow/Pargetter: just because fitness is forward-looking, functions should be retrospective. And we can even give up the term "function" in favour of "fitness".
BigelowVsVs: Function and fitness can play independent roles.
Fitness: Property of an organism
Function: functions specify the properties that together contribute to fitness. And here we can also ask why they are doing this.
Information/Bigelow/Pargetter: an attribution of fitness breaks apart into the attribution of many functions. Thus, functions are more informative in one respect, and less informative in another than fitness.
a) they do not tell us about the level of fitness, but
b) each one tells us not only what characteristics contribute, but also why.
Artifact/Fitness/Bigelow/Pargetter: artifacts are not about fitness, so function cannot be made superfluous by them. Therefore, fitness cannot be redundant in it. But instead, necessity can be redundant analogously.
Propensity Theory/Solution/Bigelow/Pargetter: provides a uniform concept of function that also applies to artifacts._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution. The note [Author1]Vs[Author2] or [Author]Vs[term] is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition.
J. Bigelow, R. Pargetter
Science and Necessity Cambridge 1990