Similarity method as a method of scientific induction. The method of similarity as a method of scientific induction The method of single similarity refers to
This method is an inference based on comparing several occurrences of the same phenomenon and identifying the real cause based on a single similarity. For example, let's take some phenomenon a and accompanying circumstances ABC. To use the similarity method, consider other circumstances where the phenomenon occurred under different and only partially similar circumstances; let's say, under the circumstances of AKM. Comparing these cases and relying on the rule causation, according to which the phenomenon cannot occur in the absence of its cause, we can conclude that the cause a there cannot be VS circumstances, since they are absent in the second case, when the phenomenon a happened again. We can say the same about the circumstances of the KM, since they were not in the first case when the phenomenon took place. a, Therefore, it remains to be assumed that a is circumstance A.
If two or more occurrences of an observed phenomenon are similar in only one antecedent circumstance, then this circumstance is likely to be the cause of this phenomenon:
ABC - a,
AKM - a,
there is probably a reason a.
When using the method of similarity to determine the cause of the phenomenon under study, it should be remembered that the cases of this phenomenon differed as much as possible among themselves in circumstances; such a selection greatly facilitates the process of finding the cause and reduces the number of cases needed for inference. To this we must add that the reasoning that leads us to the conclusion about the cause of the phenomenon under study is valid only when this phenomenon comes from one cause.
The similarity method is widely used in everyday life and science only in the first steps of research as a primary assumption. This assumption is then tested and justified using more accurate methods of establishing causality.
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Studying the discipline during one semester
Full-time department: lectures - 18, practical classes - 18, independent work students - 66. Certification: intermediate control (checking homework, testing), test.
Course program
Topic 1. The subject and meaning of the science of logic. Formal language and semantic categories (lecture, practical lesson) The process of thinking and forms of thought. Logic value. History l
test questions
1. What is the subject of formal logic and what is its significance? 2. What does the generalization of knowledge about individual objects and their properties and relationships lead to? 3. What is the difference between logical
After studying "Logic", students should
know: - the history of the emergence and stages of development of logic, the essence, content and specifics of logic as a science; - the essence and content of the principles of logic, to
Methodological recommendations for part-time students
Considering remote form teaching distance learning students, you should pay attention to the following guidelines. First, students must carefully
Laws of logic and principles of correct thinking
Introduction. general characteristics basic laws of logic. The law of identity. The law of contradiction. Law of the excluded middle. Law of sufficient reason. Conclusion. practical ass
Language as a sign system. Sign concept
Introduction. The concept of linguistic form. Languages natural and artificial. Functions of natural and artificial languages. The sign system of the language. Name, subject, function. Conclusion. Prak
Main characteristics of signs
Introduction. Definition of sign and sign system. Sign types. Three types of sign relations. Basic principles of semiotics. Conclusion. Practical task: 1. Indications
General principles for constructing truth tables
Introduction. Interpretation of propositional variables. Tabular definitions of propositional connectives. Logical Relations(by truth and falsity) between formulas. Conclusion. P
propositional calculus
Introduction. propositional logic. Validity of the propositional calculus. propositional links. The language of propositional logic. Conclusion. 1. Write down symbolically
Concept as a form of thinking. general characteristics
Introduction. Concept definition. Classification of signs. The content and scope of the concept. Concept and term. Conclusion. Practical task: 1. What
Logical structure and main characteristics of the concept
Introduction. Types of concepts. Relations between concepts. Conclusion. Practical task: 1. Give a complete logical description of the concepts (single
The meaning of concepts in cognition
Introduction. The concept as a member of a logical connection. Logical errors in concepts. Conclusion. Practical task: 1. Give an example of a logical connection
Types of concepts Generalization and restriction of concepts
Introduction. Types of concepts by content. Types of concepts by volume. Generalization of concepts. Limitation of concepts. Conclusion. Practical task: 1. Day
Types of relationships between concepts in terms of content and volume
Introduction. Relationships between concepts in terms of content. Relationships between concepts by volume. Graphic illustration of the relationship of concepts by volume. Conclusion. Practical task:
Categorical judgments
Introduction. Division of judgments by quantity. Division of judgments by quality. Unified classification of categorical judgments in the "logical square". Distribution of terms in judgment. Conclusion.
Logical relationships between categorical propositions
Introduction. relationship of incompatibility. compatibility relationships. Graphic scheme relations (logical square). The dependence of the truth or falsity of judgments on their relations. Conclusion.
Complex judgments
Introduction. Characteristics of conjunctive, disjunctive, implicative and equivalent judgments. Summary table of the truth (falsity) of these judgments Conclusion. Practical task:
General rules of simple categorical syllogism
Introduction. Terms rules. Parcel rules. Shape rules. The concept of the modes of the figures of the syllogism. Conclusion. Practical task: 1. What
Inductive reasoning
Introduction. The concept of induction. Full induction. incomplete induction. Induction through a simple enumeration. Scientific induction. Conclusion. Practical task:
Methods for establishing the causal dependence of phenomena
Introduction. Causal connection of phenomena. Five methods for establishing causality. Inferences by analogy. Conclusion. Practical task: 1.O
Hypothesis
Introduction. General characteristics of the hypothesis. Types of hypotheses. Hypothesis development. Hypothesis testing. Actual (decisive experience) and logical evidence of the hypothesis. Practical task:
Errors in evidence
Introduction. Substitution of the thesis being proved. Errors in evidence. Errors in the method of proof. Mistakes of homonymy and amphiboly. False following error. Conclusion. Prak
Logic and language
Language is a sign system, a material form through which people express thoughts. Language has five kinds: lines, sounds, gestures, colors and smells, and three forms: natural, co
The connection between thinking and language
Language and thought are inextricably linked. With the help of language, we express thoughts in a certain, generally accessible form. This is facilitated by conceptual stereotypes that impose restrictions on and
Logical and psychological
When we reason logically, we follow those principles and rules that indicate how “correct” conclusions should be drawn. The principles of logic set the standards by which we judge the quality of someone's
Semantic categories
Logical semantics studies the relationship of sign and meaning, the rules for translating abstract symbols into the language of meaningful knowledge. In logic, it is important to find the compatibility of natural and artificial language.
Process of thought and forms of thought
There are many ways to represent the thought process. For a biologist, this is the activation of groups of neurons; for a psychologist, this is a combination of a number of images in the mind; for a cybernetics, this is a process before
General characteristics of the concept
Logical thinking represents various connections of thoughts. If we look closely at the judgment, we will see that it consists of certain thoughts that we have encountered many times in other judgments.
Concept and representation
Every concept is a thought about the attributes of an object. However, not every thought about signs is a concept. In sensory cognition, representation is also thought about the attributes of an object. Presenting an object is
Concept signs
Those thoughts that form the integrity of the judgment are called concepts. A thought about an object is a concept only under the condition that the conceivable object has a similarity or difference with other objects, then e
Types of concepts
Any concept has two logical characteristics - content and volume. The essential features of the subject constitute the content of the concept. Empty concepts are not
Concept Functions
Language is a means of thinking. It expresses concepts that perform many functions. Of these, the main ones are the following: 1. Symbolic function. The concept becomes a symbol
Questions for self-examination
1. List the features of the subject in a logical classification. 2. What is the difference: word, concept, term? 3. What is the content and scope of the concept? 4. Explain the meaning of the law
Definition of concepts
Definition of concepts (definitio) is one of the most important logical operations that we constantly perform both in Everyday life, as well as in scientific process. Its meaning lies in the fact that, by revealing
Implicit definitions
If it is impossible to define concepts through generic and specific characteristics, then a description of the relationship between the defined concepts is used. The peculiarity of such definitions is that the subject is defined
Limitation and generalization of concepts
In the process of thinking, it is often necessary to concretize knowledge about the subject of thought. Clarifying the concept, we introduce new features, thereby increasing its content, but at the same time, the volume of the concept decreases.
Division of concepts
Objects that are conceived in the concept constitute a certain set, which includes separate groups of objects. In the process of division, we find out which subsets the original set consists of.
Questions for self-examination
1. What is the division of the concept? 2. What is the difference between a dichotomous division and a species-forming one? 3. What are the principles of classification? 4. What functions does the class perform
General characteristics of judgment
Judgment is an extended concept; since the concept contains some features of the object of thought, then a judgment is a form of thought in which the connection between the object of thought and its object is expressed.
Judgment Structure
Judgment as a logical form consists of the following elements: subject, predicate and link. Subject (Latin subjectum - underlying, subject) EU
Modality of judgments
The modality of a judgment (lat. modus - way, measure, inclination) expresses the degree of existence, property, relationship, displayed in the judgment. At the same time, the judgment affirms or denies the actual
The dependence of the cognitive meaning of a judgment on its form
The value or importance of a judgment for knowledge depends largely on its form. Thus, conditional and disjunctive judgments become valuable for knowledge only in connection with categorical judgments. AT
Determine the modality of judgment. Give them schemes
Example: A). Ukhta south of Vorkuta. - Judgment about the attitude of the place. xRy = R(x,y). B). There is no smoke without fire. - Judgment of existence. R is. AT).
Make diagrams of complex judgments
Example: Emission is the manufacture and issuance of money or securities into circulation Scheme: S is P (P¹ Λ P² V P³) & nb
Select three groups of judgments: compatible, incompatible, partially compatible
Example: Not a single hair fell from his head. Many wanted to see him. He lost all his hair. Some nuts are right hand threaded. Everyone arrived on time.
Tabular definition of the truth (falsity) of complex judgments
We have already said above that a proposition can be classified either as true or false, but not both. The "truth" or "falsehood" of a declarative sentence that
Questions for self-examination
1. What is judgment transformation? 2. How does the conversion of a judgment differ from the transformation of a judgment? 3. What principles does the truth (falsity) of a judgment obey? 4. Kaku
General characteristics of inference
If the main task of logic is to compose methods for acquiring and proving knowledge, then one of the main methods is inference. Inference is a way of thinking
Immediate inferences
We can derive a conclusion from the premises by transforming the latter. The truth of the conclusion in this case depends entirely on the truth of the premises, unless, of course, the rules of transformation are violated, which
Syllogism
Syllogism (Greek syllogismos - counting) is a type of inference in which it is required to determine whether a given conclusion follows from two or more judgments. Recognizing the truth
Enthymemes
In the practice of our thinking, both ordinary and scientific, we omit either one of the premises or the conclusion. Such syllogisms, in which one or another part is not expressed explicitly, are called
Conditional syllogisms
If in a syllogism both premises are taken as conditional propositions, then the conclusion will also be a conditional proposition, and the syllogism will be a mediated conditional inference. If A
Exercises
A) Determine the modality of the judgment. Please provide their diagrams. Example: 1). Ukhta south of Vorkuta. - Judgment about the attitude of the place. xRy = R(x,y). 2). No smoke
Exercises
BUT). Indicate which of the following conclusions were obtained with the help of complete and which with the help of incomplete induction: 1). All the students in our group completed the internship. 2). The angle of incidence is equal to the angle of reflection.
difference method
In order to conclude by this method, it is necessary to have two cases: the case in which the phenomenon under study occurs, and the case in which it does not occur. At the same time, they are selected so that they are similar
Connected Method of Similarities and Differences
This method combines both previous rules, so it can be formulated as follows: if two or more cases of the occurrence of an observed phenomenon are similar only in one antecedent circumstance
Accompanying change method
The method of concomitant changes is based on the principle of causation, which states that any change in the cause causes a corresponding change in the effect; and vice versa, any change
Residual method
This method is based on the following observation: if a complex phenomenon is the result of a complex cause, then each simple element of this phenomenon is caused by a simple element of a complex cause, corresponding to
Questions for self-examination
What is needed to find the real cause or the real effect? What is the "method of similarity" based on? What is necessary for inference according to the "method of differences
Exercises
Determine which methods of establishing a causal relationship are applicable, write them down in the form of a diagram and in the form of judgments that form a causal relationship. Potato sprouted in the dark
Similar inferences
Inference by analogy (Greek analogia - similarity, similarity) refers to a modification of the traductive type of inference. The only difference is that tradition is based on identity,
Exercises
Determine the type of analogy, write them down in the form of a diagram and in the form of judgments that form a connection between objects or relationships. Example: When examining rocks in Av
The concept of proof
The connection between concepts and judgments that we use to express thoughts is a reflection of the connection of objects, their attributes, their relations and their laws. But the truth of judgments is not about
Exercises
Highlight the thesis and arguments. Choose one of the forms of inference and build a demonstration. Example: Student Petrov passed his graduation project ahead of schedule, as very
Rules of evidence and refutation
In the process of proof, errors are possible that arise from intentional or unintentional violation of the rules. The proof rules are divided into three groups according to the structure of the proof:
Types of evidence
According to the purpose of evidence, they are divided into: 1) proof of the truth of the thesis and 2) proof of the falsity of the thesis. The first, aimed at establishing the truth of the thesis, is called pro
Questions for self-examination
1. What three groups of rules in proof do you know? 2. What explains the clarity and clarity in the formulation of the thesis? 3. What is "thesis substitution"? 4. Why is the truth of the argu
Exercises
Pick up the arguments and build a direct proof of the thesis. Example: Student Ivanov was summoned to court to testify. Arguments
The concept of a hypothesis and the conditions for its appearance
The word hypothesis (Greek hypothesis - assumption) has several meanings. Firstly, this is a guess about a fact that is not yet available for detection, but may manifest itself with a probability close to
Building a hypothesis
Hypothesis building is a complex logical process involving various forms of inference. In some cases, a hypothesis arises as a result of a comparison of two single phenomena, i.e. its basis is
Hypothesis development
A hypothesis is not reduced to making an assumption, but goes through a process of development, during which it is corrected, supplemented with new assumptions, and either refuted and replaced.
Confirmation of the hypothesis
In order to turn into reliable knowledge, the assumption is subject to scientific and practical verification. The process of testing a hypothesis using various logical techniques
Exercises
Gather the facts and build a hypothesis. Example: In the famous movie "Sannikov Land" it was suggested that in the Arctic
Law of Identity
It should be noted that every right thought must be definite. This means that in the process of reasoning it is impossible to replace one object of thought with another. For example, in the argument "life is in full swing
Law of contradiction
It follows from the law of identity that no thought can be identical to the thought that denies it, that is, in order to be understood, it is necessary to comply with the requirement of consistency of thought
Law of the excluded middle
That a thought can be equated either with truth or falsehood follows from the law of the excluded middle: of two mutually negating propositions, one is necessarily true at a given time, in a given place.
Law of Sufficient Reason
The correctness or truth of a thought is due to a sufficient reason for them. Indeed, we can consider this or that thought to be true only after the grounds have been given, which are already
Questions for self-examination
1. What are called the laws of thought? 2. Why are the laws of thought called formal laws? 3. How is the law of identity formulated? 4. How the law of contradiction is formulated
Exercises
Determine the requirement of which logical law is violated in the following reasoning. Example: This student did not cover the main content of the topic, but deserved
Basic logical concepts
AXIOM (gr. axioma - significant, worthy of respect, indisputable) - true judgment, which in the deductive construction of any theory is accepted without proof as and
Figure Rules
No. Figure Correct modes
Terms rules
No. Rule Example of an error Notes There must be only three terms in the syllogism Movement -
Parcel rules
No. Rule Example of an error Notes
Logic symbols
Name Image Ordinary language Formula (scheme) as it is written
In relation to the thesis
Rules of Mistake 1. The thesis must be clear and precise 1. Proposing an unclear, inaccurate thesis 2. The thesis must
Glossary
LAW OF LOGIC - a stable, essential, repetitive connection of thoughts; has the following properties: a) certainty (representation of an object in the same features); b) last
Scientific indication methods
Modern logic describes five methods for establishing causal relationships:
- similarity method;
- difference method;
- combined method of similarity and difference;
- method of concomitant changes;
- residual method.
Important! It should be borne in mind that:
- Each case is unique and individual.
- Careful study of the issue does not always guarantee a positive outcome of the case. It depends on many factors.
To get the most detailed advice on your issue, you just need to choose any of the proposed options:
by the similarity method compare several cases, in each of which the phenomenon under study occurs; while all cases are similar only in one and different in all other circumstances.
The similarity method is called the method of finding the common in the different, since all cases are noticeably different from each other, except for one circumstance.
Consider an example of reasoning by the method of similarity.
In the summer period, the medical center of one of the villages recorded over a short time three cases of dysinteria (d). When determining the source of the disease, the main attention was paid to the following types of water and food, which more often than others can cause intestinal diseases in the summer:
A - drinking water from wells;
M - water from the river;
B - milk;
C - vegetables;
F - fruits.
Information about the nutritional conditions of patients is presented in the table.
cases (Patients) | Preceding circumstances | Result |
||||
water from well | water from the river | milk | vegetables | fruit | (disease) |
|
- | + | + | + |
|||
+ | + | |||||
3 | - | + | + | + | - | + |
These circumstances served as the basis for the sanitary inspection to conclude that the spread of dysentery is connected, apparently, with the use of milk (B). Subsequently, this plausible conclusion was confirmed: the milk saleswoman turned out to be a bacillus carrier of dysentery.
The scheme of reasoning by the method of similarity has the following form:
1) ABC - calls D
2) MBF - calls D
3) MVS - calls D
_____________________________
Apparently, B is the cause of D.
Cognitive prerequisites for the logical mechanism of inductive inference by the similarity method:
1) Requires general knowledge about possible causes ah investigated phenomenon.
In the above scheme, this role is played by the circumstances A, M, B, C, F, each of which precedes D and can act as its independent cause. Such knowledge takes the form of a disjunctive proposition:
"A or M or B or C or F calls D."
2) From the previous ones, all circumstances that are not necessary for the action under study and, therefore, do not satisfy the basic property of a causal connection, must be excluded (eliminated).
So, in the above cases, D appears in the absence of F and M in the first case, in the absence of A and C - in the second, in the absence of A and F - in the third. Thus the circumstances A, C, F and M are eliminated, for what is absent cannot be the cause of what appears. The result of the elimination is expressed in a negative proposition:
"Neither A nor C, nor F nor M cause D."
The elimination method in this case performs the function of forming negative knowledge, i.e. knowledge about what did not cause the phenomenon under study D. This narrows the circle of its possible causes.
3) Among the many antecedent circumstances, a similar and recurring one in each of the considered cases is singled out, which will be the probable cause of the phenomenon.
In the above scheme, circumstance B is repeated in each of the three cases. This means that the conclusion that B is the cause of D is confirmed.
AT general view logic mechanism inductive the similarity method takes the form of deductive reasoning modus tollendo ponens divisive-categorical reasoning.
The validity of the conclusion obtained using the similarity method depends on
- on the number of cases considered and
- variety of observation conditions.
The more cases are investigated and the more varied the circumstances among which a similar one occurs, the more solid the inductive conclusion and the higher the degree of probability of the conclusion.
IMPORTANT!
The incompleteness of experience characteristic of incomplete induction is manifested in the fact that observation and experiment do not guarantee accurate and complete knowledge of the previous circumstances, among which the search for a possible cause is underway.
In the above scheme, the circumstances A, M, B, C, F, which are not a closed disjunctive set. This does not exclude the existence of some circumstance X, which remains unknown and may turn out to be the real cause of D.
The recurring circumstance B can turn out to be only a concomitant one. Moreover, in each of the three cases, B could interact with other circumstances, for example, in the first case - with A and C, in the second - with F and M, in the third - with M and C. It is also possible that B is a complex a phenomenon, one of the components of which is the true cause D.
A reliable conclusion can be obtained by the method of similarity only if the researcher all previous circumstances are known, which constitute a closed set of possible causes, and it is also known that each of the circumstances does not interact with others. In this case, inductive reasoning acquires evidentiary value.
Importance of the similarity method
Despite the problematic nature of the conclusion, the similarity method performs an important heuristic function in the process of cognition:
- it contributes to the construction of fruitful hypotheses, the verification of which leads to the discovery of new truths in science.
Its essence lies in the fact that two or more groups of factors are observed and compared among themselves, under the influence of which the same result occurs. If groups differ among themselves in all factors, except for one that turned out to be common to them, then this single factor will be the cause of the result. For example, there were several thefts, in none of which the perpetrator was identified. Comparing all the places of incidents with each other, the investigator discovers the presence of a single feature common to all thefts: fingerprints of the same person or typical hacking techniques, etc. From this we can deduce the assumption that thefts were committed by the same person. A common feature may relate to various circumstances of the crime. In some cases, a single way of committing crimes is found, in others - the same time or place of committing a crime, etc.
The single similarity method is widely used in identifying the causes of crimes. For example, it is known that hooliganism is committed under a variety of circumstances, but most often under the influence of one factor - the state of intoxication. The conclusion follows from this: drunkenness is one of the causes of hooliganism.
In criminal law, a causal relationship is studied between real social dangerous consequence and an act that took place in the past. When solving criminal law issues of causation, sometimes it is necessary to artificially create a combination various factors and to investigate the nature of what they actually produce, either possible consequences. Such constructions are material or ideal modeling.
The essence of the ideal models used in the investigation and trial of criminal cases is that the investigator mentally goes through the relationship of various factors and checks which of these combinations can lead to a socially dangerous result. If it turns out that this consequence occurs with various combinations of the factors under study, but on the condition that the same action is repeated in each combination, then it is most likely that this action, in accordance with the method of single similarity, will be recognized as the cause of the socially dangerous event. result.
For example, in one of the rooms of a student dormitory, cases of theft of students' money were established at night. It was assumed that the thefts were committed by someone returning to the hostel at night. It turned out that among the late arrivals there were various students. However, comparing the days of the theft with specific names, the investigation found that on those nights when the thefts were committed, among the students who appeared at night, there was always student A., who was first recognized as a suspect, and then convicted of theft, committed repeatedly.
The single similarity method is applicable, for example, to analyze a situation where several suspects have been identified, and the crime could have been committed by only one person. Narrowing the circle of suspects by establishing an alibi for some of them or by other verification is an inductive method of searching for a person who has committed a crime. For example, there are a number of suspects: A., B., C. and the consequence - X. Comparison of the actions of B and C. with X. does not reveal their correspondence, i.e. the actions of B. and the actions of C. exclude the consequence of X. So the consequence is connected with the behavior of A.
The single similarity method, like other methods, does not provide absolutely reliable knowledge about the causes of the consequences that have occurred, the conclusion can be formulated as an assumption, i.e. with a certain degree of probability. The probabilistic nature of the conclusion is due to the fact that scientific induction is a method of formal study of phenomena, its essence boils down to identifying logical contradictions in judgments about causality. With such a formal approach, it may turn out that the contradictions are insignificant, secondary, then the conclusion about the cause may turn out to be erroneous.
So, in the above example with the theft of money, it could turn out that one of the students returning at night was the culprit; maybe the thefts were committed by more than one and the same person.
Given the possibility of an erroneous conclusion using the method of single similarity, one should adhere to the main requirement in the course of the conclusion: the conclusion about the cause of the result under study, obtained in a logical way, must be confirmed by actual data. Scientific induction only makes it possible to significantly narrow the range of alleged causes and conduct research in a more directed and economical way.
In order to increase the reliability of the conclusion obtained by the method of single similarity, it is necessary to fulfill a number of conditions: the number of factors assumed as causes should be as large as possible; the study of these factors should be as deep as possible; the difference between factors not recognized as causes and those assumed as causes should be as significant as possible. Compliance with these conditions allows you to avoid random coincidences in the output and establish the real cause of the result.
This method is as follows. Suppose we are looking for the cause of some phenomenon a. We know from observation that the phenomenon of a mass takes place under the circumstances of ABC. Circumstance ABC is complex, it is a combination of different parts (elements): A, B, C. Which part (element) of this complex circumstance (A or B, or C) is the cause of phenomenon a by observing only one case of connection a with circumstance ABC cannot be said. Then we set ourselves the task of finding several cases where the phenomenon a exists. Observing, we establish that the phenomenon a mass is also under the circumstances of AD and under the circumstances of AFD *
Comparing these three cases, we find that the phenomenon a takes place under circumstances (ABC, ADE, AFG) that are different in everything and similar in only one thing - they all have the same circumstance A, since the circumstances B, C, D , E, F, G cannot be the cause of a, since the phenomenon a occurs even in the absence of any of these circumstances, it is concluded that the cause of the phenomenon a is the only circumstance A that is similar in all cases.
The single similarity inference can be written as the following diagram:
Example. In one regional communications office, there were three cases of theft committed in the same way (values were taken out of insurance bags without damaging them): August 4, December 20 and 25. The investigation established that in all three cases the mail was transported from one post office to the second by Sashin's cab. In all three cases, different people sent and received mail on August 4 - Petrenko and Ivanenko, on December 20 - Nikolaenko and Yakovenko, on December 25 - Vorona and Savchenko. On this basis, the investigator put forward a version that the theft was committed by the driver Sashin.
In the form of a diagram, this conclusion can be written as follows:
The application of the single similarity method consists of three successive steps.
1. First of all, all those cases are established where there is a phenomenon and the cause of which we find out.
2. Then each case is analyzed and the circumstances under which phenomenon a occurs are identified.
3. After that, the circumstances common to all these cases are found, which are the cause of the phenomenon and what interests us.
The conclusion by the method of single similarity is based on the following rule: if two or more cases of the phenomenon under study have only one circumstance in common, and all other circumstances are different, then this only similar circumstance is the cause of this phenomenon.
The single similarity method gives conclusions that are not reliable, but probable. The degree of probability of the conclusion depends on various conditions: a) on the number of cases considered. The more cases investigated, the more likely the conclusion will be; b) from the depth and thoroughness of the study of all circumstances, from the accuracy of establishing that in all cases only one furnished similar with; c) the degree of probability of inference by the method of single similarity depends only on how significant the differences of all circumstances are, except for the only similar one, which we define as the cause. The greater the difference in circumstances, the more likely it will be to conclude that the cause of the phenomenon in which we are interested is the circumstance that alone turned out to be the same in all cases.
In conclusions based on the method of single similarity, one should also keep in mind the tax. In some cases, it may be that the only similar circumstance is taken as the cause, which is itself complex and the cause of the phenomenon under study is not the whole circumstance, but only some part of it, which must be determined. In other cases, it may turn out that the circumstance taken as the cause does not act on its own, but together with others, that is, only a part of the cause or one of the causes, and we incorrectly considered it to be the only cause.
The method of single similarity is often used in investigative practice to put forward versions of the case.