I see your studies continue! Good for you.
Your example of a toaster is an artifact. This topic is about how to present scientific language without invoking teleological notions, therefore by today's scientific standards an artifact would not be a suitable example. What you have to understand is that people are predisposed to anthropomorphize. Teleological language is just language that on some level, either literally or metaphorically can be linked to goal-seeking behavior. Intrinsic teleology suggests that objects have a purpose, goals. But science has moved away from that. People have goals. Rocks don't. So, scientifically, it's problematic to characterize with teleological language explanations of non-agents. Some philosophers use anthropomorphized language, and other's object to it. (IMNSHO, it's sloppy and imprecise, but useful for explaining to non-analytical people.)
Aristotle defines the end, purpose, or final "cause" (τέλος, télos) as that for the sake of which a thing is done. Like the form, this is a controversial type of explanation in science; some have argued for its survival in evolutionary biology, while Ernst Mayr denied that it continued to play a role. It is commonly recognised that Aristotle's conception of nature is teleological in the sense that Nature exhibits functionality in a more general sense than is exemplified in the purposes that humans have. Aristotle observed that a telos does not necessarily involve deliberation, intention, consciousness, or intelligence:
That is, while Aristotle recognized that an acorn is not an agent, nonetheless, it seems hard to deny that it seems to appeal to our philosophical intuitions regarding agency. The challenge since the advent of modern science, particularly since evolutionary theory, is to explicate without metaphor or appeals to language that hint at agency. For this response, I shall instead use the oak tree as an example.
How Functional Analysis Works
Let's condense the long-winded passage "4. Cummins' View". From the IEP article: "Given a system S to have property P", explain by:
- Identifying the disposition (SEP) requiring scientific explanation (SEP) of a mereological system (SEP).
- Reducing the disposition to structure of the parts of the system by:
2a. Analysis: reducing disposition to less teleological dispositions.
2b. Instantiation: demonstrating physical structures (mereological subsystems) that embody those dispositions.
- Subsequently, recurse of component dispositions until satisfied.
- When a necessary level of accumulation of explanation has occurred, organize it and present it for peer review.
Example: The Leaf of an Oak Tree
- Every spring oak trees grow leaves and then they fall off in the winter; the challenge is to explain why scientifically.
- The disposition for the appearance of leaves in the spring therefore has to be due to the parts of the tree such that:
2a. Analysis: additional dispositions inhere to the bark, the xylem and phloem, the roots, leaves, etc.
2b Instantiation: Bark is disposed to protect the xylem and phloem and therefore may not be relevant. Through experimentation, it can be shown that during freezing, water stops flowing through xylem and phloem to the leaves. Likewise, the roots are unable to take up nutrients and water when the ground freezes. Leaves, which can be shown by experimentation to be supplied nutrients by the flow of water from the roots, phloem and xylem, are therefore deprived of nutrients. Leaves themselves contain water, and when frozen not only stop functioning, but through freeze-thaw cycles demonstrate tissue damage from intracellular water expanding.
- Since leaves are central to the process to be explained, understanding parts of the leaves is integral to a scientific explanation including an explanation of the cell wall of plants, chloroplasts, the cell membrane, etc. Repeat this heuristic for each.
- After doing the same for all subcomponents, engaging in defeasible reason (SEP), and organizing, present ideas for peer review and additional testing.
Tentative Scientific Explanatory Hypothesis: Trees loose leaves because it presents a survival advantage when dealing with freezing temperatures.
(Compare to teleological style claims: Trees loose their leaves because they want to survive; or leaves fall with the goal of preserving the tree; or it is the purpose of deciduous leaf-falling to protect the tree.
Epistemologically speaking, the transition from natural philosophy to modern scientific method has been tremendously successful for extending the dominance of will over the physical world. For 10,000 years of history, people have been devising explanations for the physical world through mythology and religion, but scientific explanation has solved some very specific problems: vaccines, internal combustion engines, the Internet which extends into local space, and rocket ships that can land themselves on reentry. It's a pretty large deviation from the previous 9,700 years. So, particularly since the logical empiricists, there has been a philosophical quest of sorts that drives what exactly is it that makes scientific explanation particularly effective. The hypothetico-deductive model was too simple, and then Hempel's formulation of the deductive-nomonological model (DN) raised the bar, as flawed as it was. And yet, it fell out of fashion, and in some extreme arguments Feyerabend took it in the other direction and insisted science resembled anarchy! But along the way, there was a lot of agreement that teleological notions should be purged from science.
Robert Cummins and Scientific Explanation
According to the IEP article Causal Role Theories of Functional Explanation, by the 1970's Cummins rejected Nagel's argument that teleological language can be translated to DN statements. From IEP:
This means functional statements in general have the following form for Nagel: The function of A in a system S with organization C is to enable S in environment E to engage in process P. And this can be expanded into an explicit explanation in this way: Every system S with organization C and in environment E engages in process P. If S with organization C and in environment E does not have A, then S does not engage in P. Hence, S with organization C must have A.
- An acorn has a final cause in the realization of an oak tree. (Aristotelian language tinged with notions of goal)
- Through natural selection, acorns change to trees to propagate genes allowing the species to survive. All parts of an acorn-oak-tree system have functions which can be understood as a collection of anatomical structures and physiological processes that occur in an ecological niche that sustain the organisms which then sustain the species. There may be multiple, functionally equivalent process, but otherwise all structures and functions can be understood through botanical functions and structures. (Note, the second explanation is free of the idea of goal-orientation.)
Which explanation is more scientific? Obviously the latter (no discredit to the genius of Aristotle who just happened to be born 2,500 years ago.)
So, the real crux is, what does it mean to be a function (etymoline.com)? According to its etymology, a function can be understood as work or purpose, but again, here we see work does not imply goals, but purpose does. So, what's going on? It's all about the language. Philosophers are wrestling with three types of terms: terms that do not imply agency, terms that imply agency, and terms that metaphorically can imply agency, but are used in a way that is often taken to be literally not implying agency. Cummins' goal is to move from Nagel's position (the last), to his own (the first).
Ultimately, the method as it has been distilled is what the article tries to convey. The article lists objections, and those objections to the methodology are fair game for discussion. What you should take away from the method is that science creates explanations largely by exploring systemic structures (mereological entities in the philosophical vernacular), and their functions (processes related to change in philosophy), and does so by stripping out any implication that acorns want, try, attempt, or have goals to become oak trees. It's comfortable and easy to anthropomorphize when communicating ideas, but strictly speaking, only agents pursue goals. There's just an uneasy tension using goal-oriented language to describe systems that taken literally have no agency.