One year before Kuhn 1961 Classic:

Ernest Nagel (November 16, 1901 – September 20, 1985) was an American philosopher of science.[1][2] Along with Rudolf Carnap, Hans Reichenbach, and Carl Hempel, he is sometimes seen as one of the major figures of the logical positivist movement. His 1961 book The Structure of Science is considered a foundational work in the logic of scientific explanation.

Rudolf Carnap (/ˈkɑːrnæp/;[20] German: [ˈkaʁnaːp]; 18 May 1891 – 14 September 1970) was a German-language philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism. He is considered “one of the giants among twentieth-century philosophers.


Conjunction (and)

A and B” is true only if A is true and B is true.

An operand of a conjunction is a conjunct.

constant conjunction

Two events A and B are constantly conjoined if whenever one occurs the other does.

For Hume,this relationship is what is meant by saying that the one causes the other, or this is all that we can understand by the notion.


Transcendental Realism +

Critical Naturalism

= Critical Realism

Bhaskar developed a general philosophy of science that he described as transcendental realism and a special philosophy of the human sciences that he called critical naturalism. The two terms were combined by other authors to form the umbrella term critical realism.

we must separate epistemology (knowledge, systems, thoughts, ideas, theories, language…) from ontology (being, things, ontics, existents, reality, objects of investigation).

Real structures exists independently of, and are out of phase with, actual patterns of events necessitating the need to perform experimentation so that scientists might make sense of their operation in a controlled and non-complex environment (that is a relatively closed environment).

constant conjunction, happens in closed systems in which event 2 always follows from event 1. This occurs only in certain situations, such as in a laboratory or similarly controlled environment. Most of reality is not a closed system, it is what we call an open-system.

                        Domain of Real            Domain of Actual            Domain of Empirical        

Mechanisms                      X

Events                                 X                                    X

Experiences                        X                                    X                                    X

The basis of causal law lay in the generative mechanisms of nature, of which we do not have direct, only mediated, experience. These mechanisms can be understood as the way things act, that is the structures, powers, and liabilities which frame an object’s tendencies as they operate and interact. These mechanisms are said to operate in both open and closed systems (but are of course more identifiable in closed systems) and may also be exercised without being manifest.

Roy Bhaskar, The Possibility of Naturalism 25:

“for transcendental realism, it is the nature of objects that determines their cognitive possibilities for us; that, in nature, it is humanity that is contingent and knowledge, so to speak, accidental. Thus it is because sticks and stones are solid that they can be picked up and thrown, not because they can be picked up and thrown that they are solid (though that they can be handled in this sort of way may be a contingently necessary condition for our knowledge of their solidity)”

structure precedes human agency in so far as it provides the material causes of human action. We are always thrown into a socio-linguistic-epistemic context in which we must act. But following Weber, the structures of society must not be reified, but operate through the mediation of human agency and social activity. ‘Society is both the ever present condition (material cause) and the continually reproduced outcome of human agency.

This dynamic relationship between structure and agency forms the transformational model of social activity (TMSA) and the basis of social scientific investigation in the relationships which constitute ‘society’.  People do not simply create society, for it pre-exists them and is the necessary condition for their activity. Rather, society is instead to be regarded as an ensemble of structures, practices, and relationships, which individuals both reproduce and transform, without which society would not exist. 

Critical Realism




Deductive inference or necessary inference:


what is inferred is necessarily true if the premises from which it is inferred are true;

The truth of the premises guarantees the truth of the conclusion.

If (All As are Bs. )
and if (a is an A)
Then, a is a B.

non-necessary inferences:

Induction By Analogy

All A’s in my sample are B’s.
My sample was large and randomly selected;
The next A, outside my sample, will probably be a B.

All revolutions in my survey have been preceded by economic crises;
My sample of revolutions was large and randomly selected;
The next revolution in the future will probably be preceded by an economic crisis

Induction by simple enumeration (universal generalization)

All “A”s in my sample are “B”s;
My sample was large and randomly selected;
All A’s in the world are (probably) “B”s.
All U.S. presidents I have studied are male;
My sample of presidents was large and randomly selected;
All presidents in U.S. history have (probably) been male

Statistical Induction (generalization to the population)

A proportion of A’s in my sample have some characteristic B;
My sample was large and randomly selected;
In the larger population of A’s, the same proportion as the sample have characteristic B
In a survey, some 90 percent of US senators accepted bribes;
My sample was large and randomly selected;
Approximately 90 percent of U.S. senators accept bribes. I can calculate my confidence interval.

Generalization to theory

Some A’s in my sample have some characteristic B;
My sample is not SRS;
I theorize that:  In the larger population of A’s, the same proportion as the sample have characteristic B
If this theory is right then I hypothesize that in a SRS that Alan is going to take, we must see that proportion.
My theory will be tested this way. and may be refuted.
In a survey, some 90 percent of US senators accepted bribes;
My sample was not SRS;
I theorize that: approximately 90 percent of U.S. senators accept bribes.
I hypothesize that if Attorney General took a random sample of senators, he will see a similar proportion.
Attorney General took a random sample of 20 senators and 18 had accepted bribe, therefore my theory is not refuted.


The inference to the best explanation (Lipton) version:

Given evidence E and candidate explanations T1,…, Tn of E,
We infer Ti which best explains E.
Amir: Pierce’s Abduction is the creation of theories that generate predictions which can be tested by further hypothesis testing based on further observations by which we can choose the best explanation.
We observe q
p1 can lead to q
p2 can lead to q
p3 can lead to q
we have to find pi that is more reasonable to be the reason we saw q

Qualitative Prediction

I studied this protestor thoroughly and I know everything about his case.

He told me that he has the intention to bring a placard tomorrow.

I think he was serious.

I infer that he will bring a placard tomorrow.

Qualitative Inference

I studied the cases of John and Mary thoroughly.

They talk the same and walk the same and think the same and mimic each other’s behavior.

John told me he is happy about what the president is doing.

I infer that Mary is probably happy about what the president is doing.

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