Ontology is a concept that means the study of being/existence and the nature of reality. Ontology asks questions such as “What is the essential substance of (or the underlying foundation of) existence?”, “What is the nature of reality?” and “Is it possible for us to perceive reality as is?”

Epistemology is a concept about how we come to know about these existing things (that ontology is interested in) and their reality. So, epistemology is interested in investigating the sources of our knowledge of reality. And,  epistemology is also interested in investigating whether we are in a state to know reality as it exits independent of us (reality as is); and whether what we are able to know corresponds to a reality that exists independent of us (independent of us knowing it).

Metaphysics is another field in philosophy, which is interested in having discussions about the nature of being, existence and the world. It is interested in the ‘first causes and the principles’ of existence and being in the world. It asks questions such as “what is the nature of reality?”, “how does the world exist?”, “What is the origin, or source of creation?”, “What is the connection between the knowing mind and the external reality?”. These kinds of questions are known as metaphysical questions that cannot be answered through scientific investigation or through the scientific methods of observation or experiments.

The argument of ‘first causes’ in philosophy refers to an absolute cause for everything that exists; thus, existence can be tied to a creator like the God. Thus, the ‘first causes’ argument is something like the following: “Things and the world exist in the first place because the God created them.”

Helio-Centric Universe means the sun is at the center of the universe and all planets circle around the sun. This view opposes the earlier version proposed by Ptolemy an ancient Egyptian philosopher, in which the earth is at the center and all planets circle around the earth; known as the geo-centric view.

Positivism is a philosophical theory arguing that positive knowledge is possible as long as science is based on observations and experiments, of the phenomena and the relations between different phenomena. In this context, the word “positive” means “certain”, thus ‘positive knowledge’ means ‘certain knowledge.’

Rationalism is most often associated with Rene Descartes (1596-1690) in modern philosophy. However, the ancient philosopher Plato is also known as a radical rationalist. Rationalism defends the idea that knowledge that is obtained through the senses lack certainty, because senses often deceive us; for example, a stick put in water seems to us as if it is bend, even though in reality it is not bend.

Dualism is an intermediate position, defended by Descartes, according to which both material and immaterial worlds exist. The material world consists of the material things (like mountains, earth, animals etc.) and the immaterial world (the world of ideas) consists of the immaterial things (like souls, spirits, God etc.).

The main difference has to do with how knowledge is constructed and the types of propositions used in the process.

In empirical sciences, the purpose is construction of empirically grounded theories; hence, one needs to check the propositions and any other knowledge claim against the empirical world (the world of experiences or the experience in the world).

However, formal sciences are based on purely logic; their conclusions are deduced from premises that are in the form of a priori analytic propositions.

Inductivism prescribes a purely empiricist orientation to science, because it believes in construction of theories based only on sense experience, thus also known as methodological empiricism. Thus, inductivism carries the problems associated with empiricism, such as the problem of sensation, the problem of induction and the problem of theory-ladennes. Inductivism is contrasted with
deductivism, which is based on deductive reasoning.

Confirmationist approach to testing requires scientists to try to confirm a hypothesis, while falsificationist approach requires scientists to try to falsify their hypothesis. Falsification is offered as an alternative to confirmation because trying to confirm takes an infinite number of cases and was not critical, while falsification was a critical procedure and just a single case was sufficient for falsification.

Nowadays, there is a distinction drawn between the terms methodology and the method. ‘Methodology’ is used to describe the philosophical descriptions or accounts of methods, while ‘method’ is used to refer to the methods or the practice that are actually employed. Thus, methodological accounts do not necessarily reflect the actual methods, because methods can be implicit, thus
taken for granted.

According to Kuhn, paradigm comes prior to any set of activities or procedures and provides the practitioners with the current state of knowledge and practices of a field. A paradigm is defined as a worldview, or an intellectual or theoretical  framework that provides guidance for the engagement of the community of scientists with their phenomena of interest.

An anomaly is defined by Kuhn as a deviation of the “paradigm-induced expectations that govern normal science” (Kuhn, 1962, pp. 52-53).

In Kuhn’s account, we find the primacy of language, in definition of a field and its demarcation from other fields of study during pre-science phase; in definition of concepts and problems; in formulations of observations, in discussions and reports of the findings during normal science phase; in discussions over the basics of a discipline and the accumulated anomalies during revolutionary phase all of which involves language. We can say language is central to Kuhn’s concept of paradigm. In fact, language comes before any interpretation in the history of science that Kuhn himself provides.

When Kuhn argued that science does not follow strictly defined methodological rules given in the traditional accounts of methodology, he meant that there was another type of foundation underlying the scientific practice. This was the social, cultural foundation and language was a central feature of this foundation that science relies on. These were also the foundations for any type of human knowledge. 

Positivism is a philosophical position, which states that societies or human behaviors function based on underlying laws just like the laws of nature identified by natural scientists.

Social scientists study the social worlds which consist of social objects, such as relations, activities and practices, traditions, laws, organizations, institutions and so on, all of which are products of social processes.

Natural scientists studied the objects of the natural world, which are physical / material things made of atoms, electrons, particles etc. and their interactions are shaped by physical forces, energies etc.

Interpretive, constructivist position has some connections with idealism, however, it differs in many respects. Constructivism has no claims to existence of an immaterial world. They are similar in the sense that both acknowledge the role of human mind in human perception, human reality, and human knowledge.