Letter from Tadeusz Czeżowski written 12.10.1954

Prof. TADEUSZ CZEŻOWSKI                                                                     Toruń, 12 October 1954

            T o r u ń





ul. Biskupia 14 apt. 15

            The issue of systematics and analysis of logical error has been incorporated into the plan of the Logic Section of the Philosophy Committee of the Polish Academy of Sciences (practical logic group); in connection with this, I have been entrusted with the organisation of group work to collect and organise empirical material in this area. I am sending you below an outline of the instructions with a polite request that you comment on both the intended work in general and on the instructions. The statements I receive will be used to elaborate a more detailed project as the basis for a consultation which will ultimately decide on the method of research.

I attach expressions of respect


(prof. Tadeusz Czeżowski)




Recording of logical errors


            Every statement inconsistent with the laws of logic constitutes a logical mistake, in particular:

a) Incorrect use of a logical term (e.g. calling an inferred conclusion a syllogism, cf. Twardowski: ‘On logical education’, Phil. Movement V – 1920, pp. 65‒71; reprinted in Dissert. and Phil. Art. pp. 185–193).

b) A definition violating the logical laws of definition.

c) A logical division violating the logical laws of division.

d) A sentence constructed in violation of the distinction of semantic categories or language levels (as in the paradox of classes or the liar’s paradox).

e) An inference that violates the rule of inferences (formal error, vicious circle, ignoratio elenchi, etc.).

f) Incorrect generalisation (an inferior statement in terms of its grounds for generalisation, e.g. the generalisation ‘some S are P’ based on ‘every S′ is P’ where S and S′ are characterised by overlapping ranges).

g) A generalisation made without a sufficient basis.

h) An unjustified analogy.

i) A lack of differentiation between a sentence stating a fact and a generalisation (e.g. when someone says ‘it is a fact that every S is P’ where this is a generalisation of facts stated in the individual sentences ‘S1 is P’, ‘S2 is P’, etc.) However, a so-called material mistake (such as a false observation or false summary, the result of a generalisation made in accordance with the laws of induction, even if they contradict subsequent observations, etc.) is not a logical error.


Logical errors are recorded when encountered:

a) in print or in writing (in scientific and popular-scientific works, in literary works, in the press and in printed material of any kind, such as prospectuses and advertisements; in official writings, in commercial and private letters, and in manuscripts, both historic and contemporary);

b) in live speech, as in readings and lectures, in discussions and conversations, in school lessons and university exercises.


Recording consists in writing down an error that has been detected, which should include:

a) quotation of the full wording of the text containing the logical error;

b) for a printed text, the use of standard bibliographic data (author, title, location and year of publication, applicable pages; for periodicals, year and issue as well); for a manuscript, mention of the author, date, identification, and indication of where the manuscript is preserved; for spoken statements, appropriate data: identification of the individual (with the letters N.N.), his or her approximate age, education, profession, the date and circumstances of the statement (in a discussion, as part of a lesson, etc.).

Errors are recorded on sheets of a uniform type and format, namely, evenly cut quarters of stationery paper. Each error is recorded on a separate sheet; if necessary, more than one sheet can be used for one instance of recording, with the provision of consecutive pagination. Each sheet should be marked with the signature of the recording individual.


            In order to organise the recording process, group directors, who organise groups of recording individuals at their discretion from among willing and sufficiently qualified persons, are recruited in various locations. Members of each group gather at intervals designated by the director for an exchange of comments and consideration of questions, while at the same time submitting the sheets on which they have recorded errors to the director. Group directors send the collected sheets to a central file, where they are numbered and ordered.