Different sources in different languages give different answers:

"Leśniewski's student Alfred Tarski, in his Appendix E to Woodger (1937) and the paper translated as Tarski (1984), greatly simplified Leśniewski's formalism. Other students (and students of students) of Lesniewski elaborated this "Polish mereology" over the course of the 20th century. For a good selection of the literature on Polish mereology, see Srzednicki and Rickey (1984). For a survey of Polish mereology, see Simons (1987). Since 1980 or so, however, research on Polish mereology has been almost entirely historical in nature.A.N. Whitehead planned a fourth volume of Principia Mathematica, on geometry, but never wrote it. His 1914 correspondence with Bertrand Russell reveals that his intended approach to geometry can be seen, with the benefit of hindsight, as mereological in essence. This work culminated in Whitehead (1916) and the mereological systems of Whitehead (1919, 1920).

In 1930, Henry Leonard completed a Harvard Ph.D. dissertation in philosophy, setting out a formal theory of the part-whole relation. This evolved into the "calculus of individuals" of Goodman and Leonard (1940). Goodman revised and elaborated this calculus in the three editions of Goodman (1951). The calculus of individuals is the starting point for the post-1970 revival of mereology among logicians, ontologists, and computer scientists, a revival well-surveyed in Simons (1987) and Casati and Varzi (1999). This is from Wikipedia in English; while I was lookig at Gestalt psychology there was a link to mereology!

Hi Paul -- Bennett & Hacker (2003) in their book "Philosophical Foundations of Neuroscience" discuss what they refer to as the mereology fallacy (attributing mental states to brain regions), but the issue was raised before them, for instance by D. Dennett in "Content and Consciousness" where he highlights the difference between the personal and the subpersonal descriptions. That's one example that I know of.

David Kellogg Lewis was considered to have introduced mereology 1991 into philosophy with his book Parts of Classes, Oxford: Blackwell Publishers

In psychology "Gestaltpsychologie"  is concerned with parts and the whole

Thank Davood, if the authors you mentioned do not attribute mental states to neural regions, what do they attribute these to?

Beatrice, thank you for these two sources. Do you use mereology in your work?

Davood, I forgot to ask, do you use the concept of mereology in your work?

Never met "mereology" for 30+ years in psychology.

Mereology: Coined by Stanisław Leśniewski in 1927, from Ancient Greek μέρος (méros, “part”) + -logy (“study, discussion, science”).

Paul: B&H's argument is that mental states can only be attributed to _persons_ in their totality and not to brains. That is, it is sensible to state "the person perceived X" or "the person decided Y", but it would not be meaningful to state "the brain [or brain region] perceived or decided".

And, no, I haven't used the concept in my work.

@Beatrice, mereology, as you discovered, comes from philosophy and not psychology. I am a psychologist but I think that mereology is a concept that could be very usefully used in psychology. I think it would be useful to introduce the philosophy of mereology to Gestalt psychology.

Davood, given the complexity of perception and how past experience is so tied into perception, I agree with B&H.

"Lesniewski, though little known outside of Poland, is held in an esteem in Warsaw comparable to that with which Frege is now universally regarded...His logical system, built up in three divisions, has the merit of keeping closer to the common or Aristotelian interpretation of certain logical constants than is usually the case in symbolic systems. The third division, called by Lesniewski Mereologic, develops the formal apparatus, a la Whitehead, for dealing with events. But my information about Mereologie is especially meager, since there is no account of it in an international language which I could consult...Unlike most other professors of the logico-analytic method and like Moore in this respect, Lesniewski rejects a purely formal approach to logic and mathematics and disagrees with the current conventionalistic interpretation of scientific systems."

Nagel, E. (1936). Impressions and Appraisals of Analytic Philosophy in Europe. II. The Journal of Philosophy, 29-53.

Mereology started in philosophical work. One of the earliest publications to use the actual word "mereology" (a 1946 paper) was published in Mind, the same journal famous for the traditions (begun by Lewis Carroll) of the Achilles and the Tortoise dialogues, some of which are classic readings in the philosophy of logic.

The lexemes "meomorphic" & "meromorph", on the other hand, are a different story. They were firmly rooted in mathematics (rather than philosophical works, albeit on formal topics), and go back to the 1890s. Meanwhile, I haven't found that most dictionaries/lexemes include an entry for meronomy or meronomic, but the term is used in linguistics and, in Croft's Radical construction Grammar it's written all in uppercase to indicate that it is a keyword.

Ahh, the sweet sound of Renaissance and Enlightenment thinkers taking a Germanic language already so infused and influenced by a distinct language family (Romance) and deciding it could really use a massive influx and derivations of affixes, adpositions, and lexemes from ancient Greek (a Hellenistic language). Apparently, English just wasn't convoluted enough already.

Different sources in different languages give different answers:

"Leśniewski's student Alfred Tarski, in his Appendix E to Woodger (1937) and the paper translated as Tarski (1984), greatly simplified Leśniewski's formalism. Other students (and students of students) of Lesniewski elaborated this "Polish mereology" over the course of the 20th century. For a good selection of the literature on Polish mereology, see Srzednicki and Rickey (1984). For a survey of Polish mereology, see Simons (1987). Since 1980 or so, however, research on Polish mereology has been almost entirely historical in nature.A.N. Whitehead planned a fourth volume of Principia Mathematica, on geometry, but never wrote it. His 1914 correspondence with Bertrand Russell reveals that his intended approach to geometry can be seen, with the benefit of hindsight, as mereological in essence. This work culminated in Whitehead (1916) and the mereological systems of Whitehead (1919, 1920).

In 1930, Henry Leonard completed a Harvard Ph.D. dissertation in philosophy, setting out a formal theory of the part-whole relation. This evolved into the "calculus of individuals" of Goodman and Leonard (1940). Goodman revised and elaborated this calculus in the three editions of Goodman (1951). The calculus of individuals is the starting point for the post-1970 revival of mereology among logicians, ontologists, and computer scientists, a revival well-surveyed in Simons (1987) and Casati and Varzi (1999). This is from Wikipedia in English; while I was lookig at Gestalt psychology there was a link to mereology!

Fascinating information Beatrice, thank you.  I am still struggling with establishing, in my own thoughts, the limits of what mereology actually is. I am at present reading Casati and Varzi's Parts and Places which makes the argument for mereotopology. This is fascinating but yet again questions the extent of mereology and perhaps suggests that it should be limited to the realms of logic. 

Andrew, in my reply to Beatrice I questioned the extent of what may be thought of as mereology and what parts and wholes can be the legitimate focus of study within the context of mereology. What are your thoughts on this?

Look at the researches of Jean-Blaise Grize. He was Prof in Neuchâtel University and he was closed to Piaget in the Genetics Epistemology Center of Genève. See also Denis Miéville (Neuchâtel University).  You will find out a good introduction in :

Olivier Houdé & Denis Miéville (eds.). Pensée logico-mathématique. Nouveaux objets interdisciplinaires. Paris: PUF. 1993

In Piaget's psychological analysis of knowledge and its development he distinguishes between two complementary categories, logical versus infralogical,. The latter is purely experiential or spatiotemporal , subsuming the construction of the object with its part-whole relations. Some neoPiagetians have referred to Piaget's infralogical  as merelogic.neoinfralogicinfralogic a

My thoughts? I can do one better: see chap. 2 ("Ontological Categorisation and Mereology") of Hackett, P. M. W. (2014). Facet Theory and the Mapping Sentence: Evolving Philosophy, Use, and Application. Alas, I am too inebriated at the moment to comment intelligently on this matter now, other than to note that you might find interesting the treatment in Henry, D. P. (1991). Medieval mereology (Bochumer Studien zur Philosophie Band 16). John Benjamins. It provides a fairly comprehensive survey of the gap of scholarly treatments between Plato & Aristotle and Leśniewski (beyond the "big names" like Maimonides, Ockham, etc.). I did enjoy your book though (even more than the one on neuroscience and art!)

I know the Henry book, thanks though and I agree it provides good historical coverage. I especially enjoy Ockham. Thanks for the positive comment on the books. I have 2 more contracts to write in this area (one Palgrave, one for Springer) and 2 books coming out  that use mapping sentences peripherally, both with Routledge net year. I hope you notice I acknowledged your comments in the Facet Theory book. I look forward to hearing more from you Andrew when your neurons have sobered up.

Alain, is this book in French" If it is my French will unfortunately not be good enough! Thanks though.

Juan, thank you for this. I know of some of Piaget's work in this area but It is peripheral to my knowledge, so thank you for bringing this to my attention. Do you have any specific sources for the categories of logical versus infralogical? Thanks, Paul

Dear Paul:

My apologies for the delay in replying.

Tthe distinction by Piaget between two distinct ways of knowing -- repertoires of schemes/structures, i.e., the Logical (or Logico-Mathematical) domain versus the Infralogical (or spatio-temporal, or object construction, or coordination of actions, or empirical/experiential or sub-logical) domain is central to his work,. However,  the infralogical  is not easy to identify in his writing, particularly in English, due to the variable terminology –  although important to his theorizing. He uses the infralogical domain as a counterpoint to the logical one, recognizing the former as the original experiential source and testing ground for the truth value of the latter. With some reinterpretations and adaptations, he explicates the infralogical using a variant of his logical models for elementary logic (logic of classes – here redefined as infra-classes – and the logic of relations. The  part-whole relations he examines developmentally in his analysis of the child’s construction of objects and space . To my knowledge he did not address the issue of how his infralogical theorizing related to Lesniewski’s Mereologic although  he was aware of Lesniewski’s work.

I have selected English  books of Piaget that refer to the infralogical domain in various alternative terms.  Perhaps the first source that a philosopher might wish to consult  is (1) E.W.Beth & J. Piaget, “Mathematical Epistemology and Psychology”, now own by Springer Publishers [original, Dordrecht, Holland : D. Reidel Pub. Co., 1966.]. Under various names, infralogical structures are analyzed in this book in Chapters IX, X, section 58 of Chapter XI, and section 62 of Chapter XII. I am using the French original version, but I imagine ordering of chapters and sections has been preserved.

Two other relevant theoretical sources of Piaget’s work in English are: (2) J. Piaget "The Equilibration of Cognitive Structures", Chicago: University of Chicago Press. Part 2 and Part 3 of this book are particularly relevant. (3) His “famous” article about Piaget’s theory [J. Piaget, Piaget’s Theory. In P.H. Mussen, Ed., “Handbook of Child Psychology”, Volume I, J. Wiley & sons, 1946/1983]

A more concrete discussion of his unique infralogical logic appears in older books. For instance, (4) his book on Space (Piaget & Inhelder’s “The Child’s Conception of Space”, Norton & Company, 1967), Chapter XV gives you his overview.

His two very original psychology books on the development of Logic are: (5) Piaget & Inhelder, book on the emergence of elementary logical structures [the English translation  is, I believe, by Inhelder & Piaget, “The Early Growth of Logic in the Child”, Routledge, 1999], and (6) Inhelder & Piaget, 1958, “The Growth of Logical Thinking,” Basic Books, Inc. In the latter book Chapter 17 might be where to start.

Finally another scholarly and useful theoretical source (7) written by a psychologist, which looks at Piaget’s later work from an epistemological perspective (the, albeit excellent, has been ignored because of a misguided early book review ! ), This is : Rita Vuyk’s “Piaget’s Genetic Epistemology 1965-1980”. Published by Academic Press in two volumes, in 1981.