Hypothetico-deductive method in Science

Hypothetico-deductive method in Science, Science education, M.Ed. B.H.U.

1. By,
Garima Tandon
B.Sc., B.Ed., M.Ed.
Banaras Hindu University

Hypothetico-Deductive Method of Science

An Overview:
 Previously induction was considered as the method of science but later on criticized
 The generalization may be falsified because induction is not based on study of all
examples. It is based on probability that is called Problem of Induction. It is not based
on all possible cases of phenomena. Even a single case may falsify your induced
phenomenon.
 It is routinistic way of gaining knowledge and not explain creativity in science
 Later it was introduced in the form of hypothetical deductive method. It advocated that
scientific method involve making hypothesis (educational guess).
 Contemporary Scientists believed that scientific theories are constructed but not
discovered (not exist but created)
 It set a scientific method free from the mechanistic approach that is profound by
inductive
 It is not routine but highly created.
 But we can’t totally replace induction. It can play a part in creating the hypothesis but
it is not only the way for doing this. It is one of them,
 Validation of each deduction helps to validate hypothesis
 It is synthesizing both the positions- the rationalist position & empirical positions
 To create a hypothesis you should be very vigilant
 Pattern in induction exist but hypothesis are created. It is a cyclic process.
Hypothesis is being created →Deduced →Tested.

 All observation in science are theory laden- It is decided by hypothesis.
Reading others’ theory → Experimentation → Findings → Exploring additional
discoveries added to previous theory → Modified theory

[Law is symbolic representations showing description of relationship b/w 2 variables
whereas theory is explanation of law]

What is H-D Method?
The philosophers of science has been engaged, for long, with the question of scientific
method and the pattern of reasoning that leads to a scientific theory. Equally important has
been the issue of discovery vs. invention of scientific theory. There has been a long drawn

2. debate over the true nature of scientific method. The two most prominent versions that present
the nature of scientific method are the inductionist version and the hypothetical version.
The hypothetical method of science is popularly known as hypothetico-deductive
method of science that consider the role of creativity, deduction and falsification or empirical
verification as the cornerstone of scientific method as against the simple observational and
inductive process highlighted by the inductionists.


How do the H-D Method evolved historically?

The traces of H-D method can be traced to the dialogues of Plato in which he mentions
about a hypothetical method as the way to gain knowledge. Later on the traces of HDM can
be found in the writings of Christian Huygens who claimed that the construction of a scientific
theory begins with conjecture(s) where conjectures are sort of explanations for some
phenomenon. It is created through an inductive process involving observational data. The
conjecture(s) are however to be verified. It is through the verification of the consequences that
are logically deduced from the conjecture(s) that a decision is taken whether the conjecture will
be accepted as a scientific explanation or it need revision or rejection.

During the nineteenth century, William Whewell (1794-1866) emerged as a vehement
critic of the simple inductionist approach of Mill, Locke and Hume. Whewell claimed that all
scientific theories begins with a hypothesis that is assumed to explain a wide range of
observations. It is through the verification of deductions arrived at from the hypothesis that a
scientific theory is established, modified or dropped down. The source of the hypothesis is
itself a creative ability of the scientists to "synthesize, to relate, and to formulate new
conceptual structures" (Velasquez, 2007). He argued that that "Our hypotheses ought to foretell
phenomena which have not yet been observed. The truth and accuracy of these predictions
were a proof that the hypothesis was valuable and, at least to a great extent, true”. (Whewell
1847).

During the twentieth century, Karl Popper contributed towards the consolidation of the
HDM through his falsification theory that stands close to the idea that scientific method is
basically deductive in nature. According to Popper, the hypothesis formulated by the scientists
as an explanation for a phenomenon, need to be "capable of being falsified through empirical
observations" (Ibid). This is to say that the hypothesis are to be verified to show it to be false.
As long as the observations fail to show the hypothesis to be wrong, it is accepted as a valid
explanation for the phenomenon.

Claude Bernard (1865) explicitly claimed that his methods involved two distinct phases
viz. inventing a verifiable hypothesis and then testing the same.

Even Darwin, who claimed his theory of natural selection as an outcome of inductive
process on public platforms, was at the core having a hypothetical notion for scientific method.

3. He observed in one of his letters that "How odd it is that anyone should not see that observations
must be for or against some view if it is to be of any service" (Darwin, 1903, Vol 1, p.195).
Thus the scientific method involves some or other hypothesis that guides the scientists in their
observations and experimentations.

Of recent origin Jacob (1988,) clarly reflects on his work in biology and notes that
science is actually an interaction of imagination- the hypothetical part and experimentation -
the empirical part and there exists a continuous interaction between the two that leads to fine
tuning of a theory.

What are the steps of the H-D Method?

HDM involves a two tier system of hypothesis (Trotta et al., 2013). A more general
hypothesis is hierarchically created at the higher level to explain certain set of observational
data. At the second level in the hierarchy there are one or more hypothesis that are deductively
created as consequences considering the hypothesis at level one to be true. These deductively
arrived consequences are subjected to further observation and experimentation to verify them.
The validity of the tier I hypothesis depends upon the verification of tier II hypothesis. Thus
we can say that HDM involve a system of hypothesis. In a nutshell the method can be
represented as follows:

a. Scientists move from a set of observations and identifies the problem of explaining the
observations.

b. Based on their observations the scientist makes a creative hunch- hypothesis that they
assume to be an explanation for the observations related to the phenomenon. This step involves
induction as well as the capacity of the scientist to synthesize those observations to create or
invent an explanation. This hypothesis forms the first tier of hypothesis that are in more general
terms.

c. The scientists then make logical deductions from the first tier hypothesis. These logical
deductions are sort of consequences that are expected to be observed if the first tier hypothesis
is assumed to be valid. These deductions are considered as second tier hypothesis.

d. The logical deductions arrived at from the first tier hypothesis are to be falsifiable i.e. they
need to be observable and hence verifiable. They are empirically tested. The consequences
deduced need to be examined against the real world processes.

e. In absence of any empirical observation that falsified the hypothesis, the hypothesis from the
first tier is rendered acceptable as a valid explanation for the phenomenon under consideration.
On the contrary the verification or experimentation process may also lead to further refining
and modification of the hypothesis.

4. The five steps H-D-M clearly established the significant role of scientists' creativity in
the development of scientific theory, it establishes that the scientific method is hypothetical in
nature and that logical deductions are followed in empirically verifying the hypothesis. The
reasoning for the inference can be represented as: If the hypothesis is true, the logical
consequences derived from the hypothesis is true. The consequences are true and therefore the
hypothesis is tenable as an explanation.


What is hypothesis?

A hypothesis is an imaginative hunch by the scientist to explain some phenomenon,
to show the relationship between certain conditions or some cause effect relationships.
According to Ayala (1994) hypothesis must have four criteria viz.

a. It should have logical consistency in that it has no logical contradictions.

b. It should have some explanatory power in that it tells something that make the phenomenon
under consideration more comprehensible.

c. It should be consistent with the theories or knowledge related to the phenomenon under
consideration that are already established, at least most of the times.

d. It should be testable i.e. the logical deductions or consequences derived logically from the
hypothesis can be tested and are tested to establish the tenability of the hypothesis as an
explanation. This condition thus represent the critical aspect of the hypothesis.