[for a brief explanation of this ongoing series, as well as a full table of contents, go here]
The tools of the trade
We have already discussed at some length one important — if controversial — philosophical tool: the deployment of intuitions. I find it interesting that rarely critics and defenders of the use of intuition in philosophy bother to look at the broader literature on intuitions in cognitive science, which is actually significant and covers fields as diverse as chess playing, nursing and the teaching of math. I have discussed some of this literature elsewhere (Pigliucci 2012), but a quick recap may be useful in this specific context.
The very word comes from the Latin intuir, which aptly means “knowledge from within.” It is no longer considered a mysterious faculty of the human mind, as it has been the proper object of study in the cognitive sciences for a while (Hodgkinson et al. 2008). The first thing to realize is that there doesn’t seem to be any such thing as a generic ability of intuition. That is, when people say that they are “intuitive” they are likely fooling themselves, or they are mislabeling a more specific aptitude they have developed. Intuition, as it turns out, is domain specific: the more we acquire expertise and familiarity with a subject matter, the more we develop correct intuitions about that subject matter. Intuition — as generally understood — is simply a form of rapid (Kahneman 2011, following up on an initial suggestion by William James) subconscious processing of information, which is offered to our slow, conscious mental processing for further checking and refinement.
This is why the literature on expertise — and in particular philosophical expertise — becomes relevant (Ross 2006; for a philosophical take on it, see Selinger and Crease 2006). Expertise develops in distinct phases, almost regardless of the specific field, moving from novitiate to proficiency to actual mastery (in an academic context, think of the roughly analogous progression from undergraduate to graduate studies and then to the professional level). The latter may require about a decade to achieve, and results in complex webs of structured knowledge in one’s mind, a phenomenon that makes it possible for experts to quickly assess a situation (or an argument), see the pitfalls, and develop a solution (or a counter-argument).
Perhaps the best studies on expertise have been conducted on chess masters (e.g., Charness 1991; Gobet and Simon 1996), in part because the task is clearly delineated and in part because it is straightforward to measure one’s proficiency in that field. When a chess master is faced with a set situation (i.e., a chess problem) that developed organically via an actual game she will have little difficulty quickly arriving at the best moves. Interestingly, when asked why she deployed certain moves rather than others, the master will often reflect on the question and slowly reconstruct a logical answer: she did not consciously, explicitly, go through those steps, because she reacted intuitively. But she is nonetheless capable of providing a reasonable justification of what she did. Even more interestingly, it has been demonstrated that chess masters’ intuitions often fail whenever they are presented with a set situation that did not develop from an actual game, i.e., with an artificial scenario that could not possibly have contributed to their store of subconscious knowledge. Of course, I am not saying that there is a direct equivalency between these studies on intuition and what philosophers call by that name. But if philosophical intuition is — at the least in some sense — something akin to the more general phenomenon that goes by the same name (as, for instance, XPhi supporters often claim), then this sort of literature ought to be taken into account.
Perhaps it is instructive at this point to briefly go back to XPhi and the issue it raises about the use of intuitions in philosophy. After having drawn a parallel with the deployment of intuitions in other fields, such as arithmetic and geometry, Sosa (2009, 101) provides a working definition of intuition for the purposes of philosophical inquiry: “to intuit that p is to be attracted to assent simply through entertaining that representational content. The intuition is rational if and only if it derives from competence, and the content is explicitly or implicitly modal (i.e., attributes necessity or possibility).” Please notice the emphasis on competence, that is, on expertise.
In response to XPhi papers showing the effect of cultural differences and/or “framing” on people’s intuitions about philosophical concepts such as moral desert, free will (but, apparently, not knowledge! See Machery et al. 2015), etc., a few observations may now be made in addition to our previous discussion. First, such differences may result from the lay subjects not having thought about those topics much (unlike, presumably, professional philosophers) — i.e., they are not experts on the subject matter at hand. Second, it is not really surprising that different background conditions, including individuals’ assumptions about the cases being presented to them, will cause variation in the responses (a point also made by Sosa); research on intuition has shown, as we have seen in the case of chess masters, that different conditions legitimately elicit different intuitions, and that even experts can be laid astray when faced with highly artificial scenarios. But of course that is precisely what careful philosophical unpacking of concepts is supposed to explore and deal with.
Moreover, according to Goldman (2007) the use of “intuition” as a term to describe how philosophers use hypothetical examples in their reasonings is actually of fairly recent vintage, tracing to Chomsky’s methodological discussions in linguistics. Goldman has also spent a significant amount of effort thinking about intuitions in philosophy. He examines a number of possible “targets” of philosophical intuitions: Platonic forms, natural kinds, Fregean concepts, concepts in the psychological sense, and “shared” concepts. I find his discussion of Fregean concepts particularly illuminating. He defines these as “abstract entities of some sort, graspable by multiple individuals. These entities are thought of as capable of becoming objects of a faculty of intuition, rational intuition.” He cites Bealer (1998) as explicating what it means to grasp a concept by rational intuition: “[W]hen we have a rational intuition — say, that if P then not not P — it presents itself as necessary; it does not seem to us that things could be otherwise; it must be that if P then not not P.”
Goldman himself, however, prefers to talk about the last two types of targets, psychological and shared concepts, as particularly relevant to philosophical discourse. A psychological concept is a mental representation by a particular individual, and that individual will possess certain intuitions about the correct and incorrect usage of that concept relatively to how she understands the concept itself. This becomes useful once Goldman generalizes from psychological to shared concepts, which originate when there is substantial agreement within a community of individuals on the (correct and incorrect) usage of a given psychological concept. Within that community, people may then decide that some individuals — by virtue of their specific training — are better, more reliable, at deploying a certain concept. These individuals are acknowledged as experts in the usage of that concept, and their intuitions about the concept become more valuable than other people’s intuitions. You see where this is going: if the concept is, say, free will, then the community of experts is made of philosophers who have thought hard and long about free will (which excludes not just laypeople, but also philosophers who do not have expertise in philosophy of mind and metaphysics). 
What I have proposed so far, then, is to recast the debate about philosophical intuitions within the more general assessment of expert intuitions, about which there is a significant cognitive science literature. It also makes sense to survey philosophers’ take on what intuitions are and how they are deployed within their profession, which is precisely what Kuntz & Kuntz (2011) have done. They point out a crucial distinction that is often lost in discussions about intuition: that philosophers actually use their intuitions for two different purposes, in a “discovery” and in a “justification” mode — only the latter being typically addressed by critics of philosophical intuitions (but see my earlier discussion of Love 2013, and his framing in terms of complementary “images” of science).
Kuntz & Kuntz conducted an online survey of 282 philosophers, focusing on what they think about intuitions in their profession. To begin with, about 51% of participants said that intuitions are useful for justificatory purposes in philosophical analysis, while a whopping 83% said that are useful for exploratory analysis. Moreover, about 70% of respondents said intuitions are not necessary for justification. These statistics paint a picture that is somewhat at odds with the common criticism of the “ubiquitousness” of intuitions as “data” in philosophical discourse. The same authors provided their subjects with seven different accounts of intuitions, and it is instructive to see that two of these were given the highest rank by a majority of respondents: “Judgment that is not made on the basis of some kind of observable and explicit reasoning process” and “An intellectual happening whereby it seems that something is the case without arising from reasoning, or sensorial perceiving, or remembering.” Another of the accounts on offer received by far the lowest ranking: “The formation of a belief by unclouded mental attention to its contents, in a way that is so easy and yielding a belief that is so definite as to leave no room for doubt regarding its veracity.”  The first two accounts (but not really the latter) are compatible with cognitive scientists’ definition of intuition and the target of their empirical research. So, intuitions — re-conceptualized as they normally are in the cognitive science literature — remain an important tool for the philosopher, a tool that is characterized by the same pros and cons as intuitions in any other field of inquiry or, indeed, in everyday life. Crucially, it seems that a majority of philosophers uses intuitions just the way they are supposed: in an exploratory rather than justificatory fashion. While in science the justification is anchored by empirical evidence, in philosophy it is the result of “unpacking,” i.e., carefully and explicitly analyzing the initial intuition (moving from Kahneman’s system I to his system II, if you will).
Intuition, of course, is not the only tool available to the professional philosopher. Others include the method of analysis, counterfactual thinking, reflective equilibrium, and thought experiments. These are all actually related to each other (and to intuitions!), so a linear discussion of each in turn is by necessity a bit artificial. Nonetheless, I think it will be useful to complete my analysis of what philosophical inquiry consists of and how it is conducted.
Beany (2009) provides a convenient overview of the so-called method of analysis, defining it as “a process of isolating or working back to what is more fundamental by means of which something, initially taken as given, can be explained or reconstructed,” and in that sense its applicability clearly goes well beyond what nowadays is referred to as “analytic” philosophy (Chapter 2). Socrates, for one, was certainly doing analysis in Beaney’s sense. As the author correctly points out, it is misconceived to think of, say, Wittgenstein’s criticism of logical atomism, or of Quine’s rejection of the analytic-synthetic distinction as blows to the method of analysis in philosophy, since such criticisms were aimed at very narrow conceptions of that method. Indeed, Beaney identifies three different components of philosophical analysis, all of which are likely applied in combination in the course of actual philosophical practice: decompositional (aiming at unpacking the components of a concept and analyzing them individually), regressive (working back to first principles), and interpretive (translating a concept into a logically more rigorous form). Much of this goes back to the Greeks, and in fact Beaney traces it to the early influence of geometry, which made a crucial impression on thinkers from Plato on, though the development of what we call Euclidean geometry is actually a result of this, not a cause (Euclid’s Elements date from circa 300 BCE, after Plato and Aristotle).
Beaney remarks that regressive analysis was the dominant form of the method in ancient Greece, and that we had to wait until the medieval period to see the development of interpretive analysis. We then see all three approaches deployed in Buridan’s Summulae de Dialectica (1330-40; see Zupko 2003, 2014). Even so, the decompositional approach to analysis obtained its most famous formulation with Descartes, in Rules for the Direction of the Mind (1684), where he says: “If we perfectly understand a problem we must abstract it from every superfluous conception, reduce it to its simplest terms and, by means of an enumeration, divide it up into the smallest possible parts” (Rule 13). As Beaney points out, it is not by chance that Descartes admitted to be influenced by geometry, to which he of course made the novel contributions that made him justly famous: “Those long chains composed of very simple and easy reasonings, which geometers customarily use to arrive at their most difficult demonstrations, had given me occasion to suppose that all the things which can fall under human knowledge are interconnected in the same way” (Discourse on Method, 1637 /2000). From there, decompositional analysis continued its good run well into early modern philosophy with Kant.
By the 20th century, according to Beaney, both so-called analytical and continental philosophy (Chapter 2) had gone beyond decompositional analysis, with the continentals’ phenomenological approach being analogous to conceptual clarification, while Hegel can be thought of as employing regression. We have to remember that analytic philosophy in the strict sense is a new beast that originated with Frege, Russell and others, and which depends on logical analysis as made possible by contemporary logic (especially predicate logic), with the term “analytic” once again reminding us closely of geometry, more so than previous uses of the decompositional approach.
Let me now turn briefly to the use of counterfactual thinking. In his Presidential address to the Aristotelian Society in 2004, Timothy Williamson (2005) pointed out that so-called “armchair philosophizing” is chronically seen as a virtue by what he labeled “crude rationalists” and, symmetrically, a vice by what he referred to as “crude empiricists.”As Aristotle himself would have readily agreed, wisdom must lie somewhere in between. Williamson makes exceedingly clear what the problem is when he says, citing the example of analytic metaphysicians (but, really, it could be any branch of philosophy): “[they] want to understand the nature of time itself, not just our concept of time, or what we mean by the word ‘time’” (p. 2), which means that we must pay attention to the empirical, although the idea of philosophizing about it is precisely that the empirical by itself isn’t going to provide us with a satisfactory answer either.
Williamson presents a detailed discussion of Gettier-type cases in the epistemology of truth (see Chapter 6) as instances of the usefulness of counterfactual thinking, which eventually brings him to the observation that “examples [used to explore our intuitions] are almost never described in complete detail; a mass of background must be taken for granted; it cannot all be explicitly stipulated” (p. 6). He then suggests — rightly, I think — that the deployment of counterfactuals is not distinctive of philosophy: both everyday and scientific reasoning make use of them all the time. For instance, if we say “there are eight planets in the solar system” we are implicitly assuming the counterfactual that if there were more planets in our neighborhood we would have discovered them by now. The fact that we do not have discovered additional planets does not logically imply that there are none, so the counterfactual conditional plays the role of allowing us what we understand to be a provisional conclusion, revisable at any time in light of new evidence. The very same role is played by counterfactuals in philosophical reasoning: they imply a “as far as we can tell given what we know” condition. Which leads Williamson to argue that intuitions and counterfactuals in philosophy, along the lines of those famously deployed in discussions of Gettier cases, are examples of human judgment no different from the judgment we reach in other applications, it is the specific subject matter, not the method, that is philosophic: “we have no good reason to expect that the evaluation of ‘philosophical’ counterfactuals … uses radically different cognitive capacities from the evaluation of ordinary ‘unphilosophical’ counterfactuals. We can evaluate [these counterfactuals] without leaving the armchair; we can also evaluate many ‘unphilosophical’ counterfactuals without leaving the armchair” (p. 13), which ought to take at the least some of the bite out of the standard criticisms of armchair philosophizing. To reiterate: philosophical intuition is not a special cognitive ability, and does not, therefore, demand special defense or scrutiny.
Indeed, Williamson’s conclusion so nicely dovetails with my main thesis in this book that it is worth (to me) to quote him again in some detail (p. 21): “Both crude rationalism and crude empiricism distort the epistemology of philosophy by treating it as far more distinctive than it really is. They forget how many things can be done in an armchair, including significant parts of natural science … That is not to say that philosophy is a natural science, for it also has much in common with mathematics.” Exactly.
I turn next to another staple of the philosopher’s toolbox: reflective equilibrium. Although the term has reached wide popularity in philosophy as deployed by John Rawls (1971) in his A Theory of Justice, reflective equilibrium is a general feature or method of philosophical reasoning, formalized in recent times by Nelson Goodman in his Fact, Fiction and Forecast (1955) in the context of inductive logic (though Nelson didn’t use the specific phrase “reflective equilibrium”). Daniels (2003) defines it fairly clearly in this fashion: “The method of reflective equilibrium consists in working back and forth among our considered judgments (some say our ‘intuitions’ ) about particular instances or cases, the principles or rules that we believe govern them, and the theoretical considerations that we believe bear on accepting these considered judgments, principles, or rules, revising any of these elements wherever necessary in order to achieve an acceptable coherence among them.” Notice Daniels’ emphasis on a coherentist approach to epistemology, as opposed to a foundationalist one. As we discussed especially in Chapter 3, in the context of Quine’s “web of belief,” coherentism seems a much more sensible way of approaching knowledge and judgment, provided that at the least some of the elements of our epistemological web are empirical facts, for the very compelling reason that it is empirical facts that allow us to move from conceptual space (where often there are a number of equally logically coherent scenarios or approaches to a problem) to the world as it actually is (where I still presume most of us will agree that things are either one way or another, but not both).
I see reflective equilibrium in conceptual space as in a way analogous to inference to the best explanation in empirical space. Neither is a perfect approach, nor does it provide any guarantee of success, but they are very sensible tools for navigating both spaces. Inference to the best explanation, for instance, suffers whenever one has not conceived of better alternative scenarios, in which case one is stuck with a “best of a bad lot” situation; it also suffers whenever insufficient or low quality data is all that is available. Analogously, reflective equilibrium doesn’t work very well if one fails to consider better (i.e., more coherent with the available facts and assumed notions) scenarios, or if one’s knowledge of the relevant elements is insufficient or faulty. Nevertheless, these are the sort of problems that negatively affect (and impose limits upon) any kind of human reasoning, about either matters of fact or relations of ideas (or anything else), as Hume would put it.
Daniels (2003) helpfully distinguishes between a narrow and a wide form of reflective equilibrium, though I think it is better to treat these as two points of reference along what is essentially an epistemic continuum (analogous, I suspect, to the difference between Duhem’s and Quine’s theses — respectively narrow and wide — as discussed in Chapter 2). Daniels’ example of narrow reflective equilibrium is the case of rationing of medical care according to the age of the patient. At first glance, one might think that this is similar to rationing by, say, sex, or ethnic background, which would, presumably, be unethical. However, further reflection shows that age is a different biological phenomenon from the other two (for instance, because we all age, but people can’t change sex without medical assistance, and simply don’t change ethnic background). Rationing care by age, therefore, does not have to be discriminatory (and it may thus be morally acceptable), and it could very well turn out to be a highly sensible practice in terms of both efficacy and cost. This qualifies as a narrow type of reflective equilibrium because a large number of background assumptions and a lot of factual knowledge have been left unchallenged in order to focus on a fairly specific debate.
To move from a narrow to a wide exercise in reflective equilibrium one can contemplate the famous example of Rawls’ questioning of the very tenets of utilitarian ethics, which may have been treated instead as a background assumption in the previous instance. Wide reflective equilibrium, in other words, brings under scrutiny some of the broader axioms of our thinking. Just as in the case of the difference between (narrow) Duhem’s and (broad) Quine’s approaches in philosophy of science and epistemology, one needs to keep in mind that most actual applications will be on the narrow side of things, as only occasionally it pays off to broaden the circle of questioning that far.
Naturally, there are a number of standard criticisms to the practice of reflective equilibrium, most of which, I think, seem to miss the point. For instance, it is argued that reflective equilibrium depends on judgments (say, in ethics) that are founded on certain “intuitions” which are in themselves questionable or can be challenged. This is certainly true — with the caveats about philosophical “intuition” mentioned above — but that very same criticism applies to pretty much any human judgment, in both conceptual and empirical matters. Yes, any given judgment can be challenged, and if so then it needs to be defended, unpacked, argued for, etc.. In other words: welcome to philosophy!
A second common criticism of the method of reflective equilibrium is a special instance of the general problem with coherentist views of truth: as Hare (1973) wrote in response to Rawls, fictional scenarios (say, in a novel) can also be made coherent, but one is hardly thereby justified in accepting them as truthful. But presumably philosophers will always be concerned with how things stand in the real world, i.e. their judgments will be, as much as possible, informed by — and anchored to — our best understanding of empirical facts. Although such facts themselves are revisable, theory-dependent, etc., it is the full web of beliefs that makes reflective equilibrium a dynamic practice, whose particular status at any given moment can always be reassessed if new facts and/or arguments come to light. Compare that with the static description of a fictional scenario in a novel and the difference ought to be obvious.
A theoretically more serious, but also much less impactful in practical terms, concern is that it is actually surprisingly difficult to provide a philosophically satisfying account of the very concept of coherence. What is required for reflective equilibrium is stronger than the simple lack of straightforward logical contradictions, and is more akin to a Bayesian-type judgment as deployed in scientific inferences to the best explanation. I think, however, that the project of providing a good account of coherence can proceed of its own accord without philosophers having to await for a final outcome in order to practice reflective equilibrium, as long as they are very clear about why they think a certain set of beliefs and empirical facts is more “coherent” than another, and are willing to defend such judgment when challenged.
Another classic tool available to philosophers (and to scientists) is the thought experiment. Examples in the sciences abound, as is well known, from Newton’s bucket to Schrödinger’s cat. In fact, the very term (“Gedankenexperiment” in German) appeared to have been introduced by 19th century physicist Ernst Mach, though the approach is much older than that. As J.R. Brown (2002) points out, one of the most appealing (and, as it turns out, wrong) thought experiments was advanced by Lucretius in De Rerum Natura, where he attempted to show that space is infinite by conjuring a hypothetical scenario in which we are able to shoot a spear through the universe’s boundary. The logic is solid: if the spear goes through the boundary, then it is not really a boundary; if it bounces back then there is an obstacle that must itself be located in a portion of space beyond the alleged boundary. But Lucretius didn’t know about the possibility of spaces that are both unbounded and yet finite (Einstein 1920). The fact that the experiment eventually failed is no argument against the use of thought experiments in general: first, because other such experiments succeeded; second, because plenty of empirical experimental results are also eventually overturned by further discoveries; and third, because we still learn something about how to think about the specific matter in question (in this case, space and infinity) by contemplating why exactly the outcome of the experiment (thought or empirical) had ultimately to be rejected.
Just like the case of intuitions, however, one may reasonably ask on what grounds we rely on thought experiments, i.e., what, exactly, are the epistemological foundations of this approach to theorizing? There is a large literature on this topic, and a good recent summary of the major positions has helpfully been provided by Clatterbuck (2013). There are at least three accounts that try to make sense of how thought experiments work: they may represent an example of Platonic knowledge; they may be a pictorial form of standard inductive arguments; or they may represent a special type of induction.
Starting with the suggestion that thought experiments give us access to a Platonic realm of ideas, so that we can somehow gain a priori knowledge about the physical world in just the way we gain mathematical knowledge, the argument in defense of this position is put forward by J.R. Brown (1991), and Clatterbuck reconstructs it this way:
Premise 1. Mathematical Platonism is true.
Premise 2. Mathematical Platonism entails that numbers are outside of space or time.
Premise 3. Mathematical Platonism entails that we can have intuitive knowledge of numbers.
Premise 4. Realism about laws is true.
Premise 5. Realism about laws entails that laws of nature are outside of space and time.
Premise 6. If we can have intuitive knowledge of numbers which are outside of space and time, then we can also have intuitive knowledge of laws which are outside of space and time.
Conclusion: We can have intuitive knowledge of the laws of nature.
To unpack: Brown assumes two controversial positions in metaphysics, namely mathematical Platonism (see my skepticism about it in the Introduction) and realism about laws of nature (see Cartwright’s and others’ skepticism about that, in Chapter 4). From these two premises, and from what they logically entail, he arrives at the conclusion that we can obtain intuitive knowledge of the laws of nature, and suggests that thought experiments are one way to obtain such intuitive knowledge (there goes “intuition,” again!). The argument is valid, but it is an altogether different issue to establish the soundness of its premises.
Most scientists, I wager, would have no problem with P4, and therefore must accept also P5. P2 and P3 are tightly connected with P1, so the latter may be the obvious target of criticism. But, as we have already seen, a good number of mathematicians and philosophers of mathematics do not find mathematical Platonism to be a bizarre idea at all. Still, even if we provisionally accept mathematical Platonism, for the sake of argument, Clatterbuck suggests that the real stumbling block is actually P6: it embodies an argument from analogy, whereby mathematical truths are taken to be of the same kind as physical laws. This is metaphysically questionable, since mathematical truths are necessarily such, while physical laws appear to be only contingently true (i.e., in no possible world a given mathematical truth becomes untrue, while there are many possible worlds where our natural laws do not hold). Another way to put the point is that we routinely arrive at mathematical (and logical) truth simply by thinking about a mathematical (or logical) problem, but we usually need observations and/or experiments to gain any knowledge of the physical world — and this is because the latter is a contingent subset of a number of logically possible worlds, a subset that can only be pinpointed empirically.
A second possibility is that thought experiments are nothing but standard arguments accompanied by pictures, a position that has been defended, for instance, by Norton (2004). According to him, what Galileo, Einstein and others have been doing in this respect is simply to present an inductive or deductive argument, peppered with pictures to make it more vivid to the intended audience. The point being that the mental “pictures” (e.g., Galileo’s two bodies of different weight falling separately or linked to each other; Einstein’s beams of light) are not necessary for the argument to go through, they are just embellishments with rhetorical but no epistemic force. Essentially, Norton is being parsimonious here: if we assume that thought experiments are just standard arguments plus pictures (where the latter play no additional epistemic role), then we don’t need to invoke Platonism.
Clatterbuck, however, thinks that Norton is being too parsimonious, missing an important part of the action. Imagine a concrete problem in physics, say, the dynamics of the fall of two bodies of different weight, either linked to each other or not; we can begin by abstracting away all irrelevant or distracting factors, such as air friction that interferes with the fall of the bodies; we arrive at certain conclusions concerning the problem, in this case that Aristotelian physics applied to the hypothetical experiment leads to a logical contradiction, as Galileo did; finally, we generalize our findings to the real (i.e., not idealized) world. What we have as a result of this procedure, of course, is a thought experiment. But notice that the idealization of the circumstances played a crucial role in the construction of the experiment. That is, according to Clatterbuck, the “picture” part of the inductive reasoning we just deployed is not simply a pretty but ultimately dispensable accessory, it is a crucial aspect of what’s going on. The result is something different from, say, enumerative induction, since we don’t have to “observe” more than one case to infer our conclusions: the (idealized) case is sufficient by itself to yield a logically valid inference. The upshot is that thought experiments embody a type of inductive reasoning, but that such reasoning requires idealization or abstraction to yield the conclusion from a single instance to a generally valid class of cases. In a sense — when done well — thought experiments are more powerful than standard enumerative induction, which after all is based on always fallible collections of observations. There is much more to be said about thought experiments, including interesting discussions about what, exactly (if any!), is the difference between a thought experiment in science and in philosophy. Nonetheless, thought experiments have clearly yielded many fecund lines of inquiry, and will certainly remain an essential part of the philosopher’s toolbox.
 Goldman does add the caveat that many philosophical discussions are about folk-ontological concepts, not technical terms. I submit, however, that philosophical discussions of this type begin with folk-ontological concepts, but then mold them in a way that transforms them into technical terms. It is at that point that philosophical expertise becomes paramount and that laypeople’s understanding of the newly molded concept becomes pretty much irrelevant to philosophical inquiry. Unfortunately, the frequent lack of appreciation that philosophers and laypeople may be using the same words but meaning different things ends up generating a lot of unnecessary confusion.
 As a philosopher of science, I also found interesting that colleagues in my field turned out to think that the role of intuition in justification in the course of their practice is far less important than philosophers who work on epistemology, ethics, metaphysics and philosophy of mind.
 As one can see, it is really difficult to get away from the i-word in philosophy, no matter how hard one tries!
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