Exact science
Americans physical chemist Juliana Goates and chemist and thermodynamicist Bevan Ott’s 2000 classification of thermodynamics as the preeminent example of exact science, per historical citation of Edward Guggenheim’s 1933 definition of thermodynamics as an "exact mathematical science", like classical mechanics and electromagnetism. [6]
In science, exact science, as contrasted with inexact science, is a branch of knowledge tending towards the use of quantitative treatment, nearing precision, in respect to measurement, explanation, and prediction; generally described in the language of mathematics.

Thermodynamics
In 1809, American science historian Fielding Garrison, in his “Gibbs and his Relation to Modern Science”, correctly defined thermodynamics as an exact science: [5]

“In this sentence [“heat is motion”] from New Instruments [1620] it is clear that Bacon, like Descartes, Count Rumford, Sir Humphry Davy and Young, had a more or less definite notion of the dynamic nature of heat and its convertibility into work. But the exact science which treats of heat as a mode of energy begins with the publication, in 1824, of the Reflections on Motive Power of Fire of Sadi Carnot, who Lord Kelvin calls the ‘profoundest thinker in thermodynamic philosophy’.”

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Objection
Some would claim that there is no such thing as exact science; the following being one example:

“The physical sciences claim that they are exact sciences but they are at best correlation with observations.”
Mirza Beg (2014), “Beg-Thims dialogue” (post #4), Jul 6.

Beg, to clarify, here, who employs physicochemical methods as the basis of his sociology theory, is attempting to say that physical sciences are inexact so that he can leave margin or fudge-factor room in his position, as an ontic opening, so that he can sneak in Islamic argument into the basis of his theory at any point.

In short, in most cases, however, statements, such as above, are made owing to an inherent and underlying religious-siding objection and or bias.

See also
Hard science
Pseudoscience
Real science
Soft science

Quotes
The following are related quotes:

Life is not an exact science, it is an art.”
Samuel Butler (c.1870) (Ѻ)

“Many persons indeed seem to entertain a prejudice against mathematical language, arising out of a confusion between a mathematical science and an exact science. They think that we must not pretend to calculate unless we have the precise data, which will give a precise answer to our calculations; but, in reality, there is no such thing as an exact science, except in a comparative sense.”
Stanley Jevons (1871), Theory of Political Economy (pg. 6)

“It is a common observation that a science first begins to be ‘exact’ when it is quantitatively treated. What are called the exact sciences are no others than the mathematical ones.”
Charles Peirce (1878), On the Doctrine of Chances [3]

“Although this may seem a paradox, all exact science is dominated by the idea of approximation.”
Bertrand Russell (1966) [4]

Dobereiner helped in refining Russian platinum, discovered catalysis, and reported his work to Goethe. We can only suspect that Dobereiner read the tragedy Faust and the novella Elective Affinities. The latter work of art gave impulse to a new scientific field named 'human chemistry'. In the exact sciences there are quantitative measures of estimation of each value: mass, length, force, energy. In the humanistic disciplines (history, philosophy, psychology) as well as art there are no quantitative criteria. This is similar to the question of how to measure beauty, love, friendship, democracy? The function named Gibbs energy defines ‘love’ between substances [and][possibly] people ... and is similar to Hamlet’s ‘to be or not to be?’ of William Shakespeare.”
Alec Groysman (2011), “Use of Art Media in Engineering and Scientific Education” (Ѻ) [2]

References
1. Jevons, W. Stanley. (1871). Theory of Political Economy (exact science, pg. 6). MacMillan and Co.
2. Groysman, Alec. (2011). “Use of Art Media in Engineering and Scientific Education” (§3.4: Human Chemistry), Generative Art Conference, XIV (papers) (photos), Dec 5-7, Roma, Italy, at CRUI Frescos Hall, Angelica Library Gallery. and Cervantes Institute Gallery.
3. (a) Peirce, Charles S. (1878). On the Doctrine of Chances, with Later Reflections (pg. 61). Publisher.
(b) Bynum, W.F. and Porter, Roy. (2005).Oxford Dictionary of Scientific Quotations (pgs. 488-89). Oxford University Press.
4. (a) Russell, Bertrand. (c.1965). “Quote”, in: The Viking Book of Aphorism (editors: W.H. Auden and L. Kronenberger), Publisher, 1966.
(b) Bynum, W.F. and Porter, Roy. (2005).Oxford Dictionary of Scientific Quotations (pg. 529). Oxford University Press.
5. Garrison, Fielding H. (1909). “Josiah Willard Gibbs and his Relation to Modern Science, Parts I-IV” (pdf), Popular Science Monthly (1:474), Part I: 74(27):470-84, May; Part II: 74:551-61, Jun; Part III: 75:41-48, Jul; Part IV: Vol #:191-203, Aug.
6. Boerio-Goates, Juliana, and Ott, J., Bevan. (2000). Chemical Thermodynamics: Principles and Applications (pgs. 1-2). New York: Elsevier Academic Press.

Further reading
● Laidler, Keith J. (1986). “The Development of the Theories of Catalysis” (abs), Archive for Historical Exact Sciences, 35(4): 345-74.
● Ternyik, Stephen. (2013). “Natural Law Social Science: A Method of Socioeconomics as an Exact Science” (pdf), Journal of Human Thermodynamics, 9(3):43-54.

External links
Exact science – Wikipedia.

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