Science is a systematically structured set of knowledge about the Universe, obtained through observation and reasoning, which allows the deduction of principles (theories) and general laws.

Science is knowledge of the real nature of the Universe.

Any real conception from any portion of the universe, fully or partially verified, constitutes a scientific concept.

To achieve comprehension of natural phenomenon, we appeal to the scientific method.

The scientific method is not unique or fixed, it has variations, but results must be acceptable, and in agreement with observations.

The method of investigation in Biology is the hypothetical-deductive method.

The term "hypothetical" denotes two or more hypotheses that should be formulated prior to experimentation.

The term "deductive", on "hypothetical-deductive", refers to obtaining a conclusion about particulars from a general or universal concept.



Scientists take natural facts as a model of truth. A scientific statement can be assumed as factual only if it is based on the universal theory of truth.

Scientific statements have to include all three theories of truth

Theory of Coherence - The concept suggests that primarily a statement should be consistent with other statements with which such affirmation is related. It refers to the descriptions of real phenomena. A description should always be coherent with the observed phenomenon.

Theory of Correspondence - The term refers to the correlation between thought and reality. A statement is a truth only if it corresponds with the observed facts. It relates to symbols (models). A model must correspond with reality.

Pragmatic Theory - This scheme proposes that the truth must be tested through its functional effects on certainty. This theory refers to scientific observations of nature. Any description of a model should be demonstrated as a function of the real observed phenomenon.

The three theories of truth are exactly related at specific points, for example, the OBSERVED AND PERCEPTIBLE PHENOMENA. Thus, scientific theories must be based on all three theories.

If a concept presumes to be true, but is not coherent in the context of realistic ideas related to such a concept, it should be rejected as a false conception, because the false notion, consequently, would not be in correspondence with reality, nor could it be tested because it would not have a reasonable effect.



Skepticism is good for science because it serves to influence the critical assessment of hypotheses, theorems and theories. On the other hand, many skeptics often misinform their readers about some truthful theories, because they are not on familiar terms with science. Consequently and erroneously, everything that is unknown to them is considered unscientific or pseudoscientific. My advice to skeptics of this kind is to become familiar with the documents and examine the bibliography every serious author appends to his or her writings, reports and articles.

There is another type of skeptic, unaware of the differences between hypothesis, theorem and theory, who immediately consider any new theory, theorem or theory they may stumble across, as “unfeasible to be verified”, simply because they are ignorant of the background research data underpinning the theory. This is the case with the definitions of life. The theory of life has been summarized as an operational definition.

An operational definition is a description of a variable, a term, or an object given in terms of the specific process or the set of corroboration assessments used to determine its existence and importance. The properties described through an operational definition should be made publicly accessible so that one or more persons, other than the person who defined the concept, can measure it or test it independently for themselves at will.

An operational definition is generally designed to model a conceptual definition; to be precise, by using words and concepts to describe a variable. However, those descriptive concepts must be consistent with truth, and they have to correspond with reality or with other theories that have already been demonstrated as a reality of natural origin. Nature –or Cosmos— is the source of the factual data for the sciences. That is why we classify biology, physics and chemistry as factual sciences or natural sciences.

As the saying goes, all that glitters is not gold; thus, I respectfully suggest to certain skeptics that they become meticulously familiar with science before judging the hypotheses, theorems and theories of others to be false or not supportable.



Sciences are classified in two main groups:

1. Factual Sciences: Sciences that are based on observable natural facts. Factual sciences are Biology, Physics and Chemistry, with all their derived disciplines. Factual sciences use two methods of work, the Scientific Experimental Method and the Scientific Informative observational Method, both make use of two objective methods, the Hypothetical-Deductive Method and the Hypothetical-Inductive Method.

2. Formal Sciences: Sciences that depend on logical reasoning and work with ideas created by the human mind. The method of work is the Logical Inductive Method, with all its variants. Formal sciences are Mathematics, Sociology, Anthropology, psychology, Economy and Philosophy, each one with all of its branches.

This Internet site deals with Factual Sciences, in particular, with Biology and all the fields of this science. On many articles we report conclusions obtained from the Scientific Experimental Method (see, for example, the page on Septoria tritici) as from the Scientific Informative Observational Method (see, for example, the page onAbiogenesis).

Observational means “based on pure observation”. Observation is performed with our simple senses or with the aid of appropriate instruments. Astronomers and Cosmologists base most of their annotations on the Observational Method because the objects of their study are out of reach of the researchers.

Experimentation is the method par excellence that we scientists use to verify hypotheses emanating from the observation of natural phenomena. Biology, Physics and Chemistry are sciences that use mainly the Experimental Method, although in some particular cases they resort exclusively to the Observational Method. For example, most studies on Evolution and Genetics.



In general terms, we should follow a systematization to obtain a valid deduction about something. This systematization is summarized in the steps of the Scientific Method.

Steps of Scientific Method

I should say that this explanation is a general description of the scientific method. The procedure does not have to follow exactly the arrangement described below.

The first step in any investigation is OBSERVATION. Observation consists of setting our attention on a portion of the Universe. Through observation we identify specific realities or events from the cosmos by means of our senses.

Once the observation is executed, the researcher elaborates one or more questions, generally ingenerated by the curiosity of the observer. These questions constitute a PROBLEM. The questions MUST MATCH with the observed phenomenon and must adhere to objectivity.

The investigator should always bear in mind that questions that begin with "why" are always very difficult - if not impossible - to answer. The objective investigator prefers to start with questions such as "what", "how", "where", or "when". The question could also be "what is it for".

Through INDUCTIVE REASONING, the observer then tries to give one or more logical answers to these questions. Each answer is a tentative introduction that can serve as a guide for the remainder of the investigation. These preliminary solutions to a question are called HYPOTHESES.

HYPOTHESIS is a tentative statement that can be submitted to experimentation to verify whether it is false or true.

After he has enunciated one or more hypotheses or proposed explanations, the researcher can then elaborate one or more PREDICTIONS, which must be consistent with the observations and hypotheses. To do this, the researcher uses DEDUCTIVE REASONING.

Each hypothesis should be submitted to an exhaustive test called EXPERIMENTATION. The results of experimentation will determine the final character (false or true) of the hypothesis.

Experimentation can be performed in diverse ways, but controlled experimentation is a characteristic of the scientific method, to the extent that other simpler systems are not viable for the purpose of science.

In controlled experimentation we need two groups to test: one group is called the control group or witness group, and the other group is called the experimental group.

Both the control group and the experimental group are submitted to the same conditions, excluding the variable that has been chosen for the study. The control group is not submitted to the change, while the experimental group is.

The results are observed and the differences between both groups are registered.

If the investigator notes a difference between both groups, then an answer can be deduced.

As the investigation advances, false hypotheses are rejected one by one, until only plausible verifications remain of the hypotheses initially presented.

When a hypothesis is proven true, scientists then process a final statement, which, in science, is called a THEORY.

A theory is a partially or totally true statement, proven by means of experimentation or natural and observable evidences, for one time and one place only.

If a theory is verified as true for all times and places, it would then be considered a LAW.

A theory is subject to changes, a law is immutable and permanent. A law is comprobable at any time and place in the Cosmos. However, a theory is truth only for a certain place and a given time.

We should make it clear that in the sciences there are important differences of meaning between the terms: hypothesis, theorem, theory and law.

A scientific HYPOTHESIS is a provisional solution for a question generated through the observation of an event. The hypothesis can be false or true, so each hypothesis must be tested by experimentation. For example, all reports on the origin of AIDS are hypotheses.

A scientific THEOREM is an idea or a proposition which is considered demonstrably true. In mathematics, a theorem is a proposition that has already been proven or can be confirmed by means of unequivocal assumptions. For example, the theory of the Inflationary Universe, which, when released for the first time, was presented as a mathematical model. Now that modern observations of real phenomena in the Universe have confirmed the model, the theorem has been developed into a theory.

A scientific THEORY is a statement that must contain a setting of real evidence. A theory is correct only if it has been able to withstand rigorous testing, and it will only be true if it is in concordance with facts. A theory can be reworked as new evidence is accumulated, but the background truth of a theory can never be altered. Scientific theories are true only for a given time and place. They may not be true in other parts of the Universe. Evolution is a good example of a scientific theory.

A scientific LAW is a statement that is true and valid for all times and all places in the known Universe. A law is true and valid everywhere, for all times. For example, the Laws of Thermodynamics, the Laws of Gravity and the Axiom of Biogenesis are good examples of scientific laws. The Axiom of Biogenesis is one of three Biological Laws. The other two are the Intransference of Life and the Irreversibility of Life.

I have noticed a semantic problem in many non-scientific dissertations that taken together point to a generalized mistreatment of the term "theory". The confusion is perhaps attributable to the popular idea that the term "theory" applies to all non-verified perceptions, be they scientific or not.

But in science, there are considerable differences of meaning between the terms hypothesis, theorem and theory. For the scientific community, a theory is a true statement applicable for one time and one place because it is based on evidence and it has been confirmed by testing. For example, the Cell theory, which says that all living beings are constituted from cells.



We raise guppies here in the Biology Cabinet laboratory. We have two aquariums for this purpose.

OBSERVATION: In one of the aquariums we observed a decrease in movement of some of the fish. This became aggravated to the point where some of them began to die.

QUESTION: What was the cause of death of the guppies? That was our question and it was followed by several hypotheses. The hypotheses were these:


1. The fish were poisoned by some kind of chemical product added to the water.

2. The tank was placed too near (3 feet) to a lab stove, and excessive heat killed the fish.


To test case number 1, we decided to carry out a small controlled experiment:

We separated the guppies from the healthy aquarium into two groups: a group of 10 guppies was placed in the "healthy Aquarium" as the control group, 5 females and 5 males. A second group of 10 guppies was placed in the "fatal aquarium" as the experimental group, 5 females and 5 males. We maintained the same conditions for both groups.

After 48 hours, the experimental group (the fishes in the fatal aquarium) began presenting symptoms of lethargic movement.

The condition of the control group, on the other hand, remained normal.

After 57 hours, individuals from the experimental group began to die.

Our preliminary conclusion was that only in the fatal aquarium did the death of guppies occur. The problem, therefore, resided in this aquarium.

We had only then to test for a toxic substance as the cause of the deaths.

We entrusted a chemical study of the water from both aquariums to an allied laboratory.

The results revealed that there were no toxic substances in the water of either aquarium. The differences in the chemical composition between both samples of water were not significant.

Therefore, the second hypothesis was also partially rejected (always a degree of uncertainty remains due to various factors tied to the analytic processes).

Finally, we decided to test the second hypothesis. We checked the water temperature in both aquariums. Wow! the water in the fatal aquarium was 4.7 °C hotter than the water in the healthy aquarium.

We relocated the fatal aquarium 15 feet further away from the stove. From then on our guppies stopped dying from an "unknown cause", at least until now.

CONCLUSION: Experimentation permitted us to know the real cause of death of the guppies. When we verified the third hypothesis, this was considered a theory.

Please, read another example of controlled experimentation here: Wood's Experiment Repeated



Dogma is a peremptory-formulated statement of a religious or philosophical doctrine proposed for belief not for discussion.

As dogmas are pronouncements from authority, they are considered compulsory statements. Thus Dogmatism is a system of ideas that is based on simple assertions that have not been scientifically validated.

Some good examples of dogmatism are creationism, the existence of an immortal soul, the infinitude of the Universe, the panspermia hypothesis, the equation of extraterrestrial life, etc.

When science was controlled by religion, it was plagued by aberrant and unreal beliefs. All new scientific premises had first to be studied and then sanctioned by the clergy so that if the knowledge derived could not be supported by Scripture, it was considered heresy.

Some examples of this are: The Earth is flat; the Earth is the center of the solar system; stars, Sun and planets rotate around the Earth; spontaneous generation; permanence of the species; etc.

We perhaps laugh at these beliefs today, but for the thousands of martyrs to science who falsely charged with witchcraft and heresy for promoting views contrary to the teachings of the Church, it was certainly no laughing matter. Perhaps the most poignant case is that of Giordano Bruno who, during his Inquisition, refused to accept the Churches doctrine on the nature of Christ and steadfastly refused to recant his views on the nature of the universe. For his "crimes", Bruno, one of the greatest thinkers of his day, was sentenced to death and was taken, with his tongue in a vice, to a public square in Rome and burned at the stake (1600 AD).

It is common to find in some scientific papers references to another scientist's prior success or achievement to endorse an assertion made by the author; for example, “Popper, who established the basis of the scientific method assured that every theory invariably must be checked out as false”. For Popper, of course, the availability of a theory to be tested by experimentation or through careful observation of the phenomena that generated a theory, is already taken as given. But in reality this is not always the case. For example, we are sure that the Earth orbits around the Sun, but when Copernicus first enunciated his theory of the position of the Sun and the planets in the Solar System (1530 AD), no experimental mechanisms had been invented that were capable of probing Copernicus's theory. If we apply Popper’s rule in the same sense as it is given by some writers, then Copernicus's theory would have been rejected very early in its development, simply because no one would have been able to experimentally test it in face of multiple observations on the Retrograde Motion of the exterior planets (other than by careful observations). So when one sees someone supporting there own statements with phrases like “Einstein said so”, or “Newton believed it”, or “The great Carl Sagan, of venerable memory, was sure of the existence of extraterrestrial beings”, one should closely investigate the statement being supported in this way.

Another example: It was not until 130 years after its publication that an experimental design was devised that could be used by scientists to test the veracity of Darwin's Theory of Evolution (1859 AD) or, to put it another way, it wasn't until 1969 that scientists developed the tools to reveal genomic DNA sequences. Nevertheless, millions of observations by thousands of scientists made in those 130 years in the absence of experimentation deeply rooted the authenticity of Darwin’s theory, so we have need of experimentation and persevering observations on nature to recognize that Evolution is a real biological phenomenon.

Since we are speaking of Darwin, the reader should be informed that some academics overexploit his success in order to promote their own personal beliefs. For example, certain people reason that: If Darwin's theory does not provide an explanation for the complexity of the eye, then there is no valid explanation for its evolution, and the eye, therefore, can be explained only as the creation of an intelligent designer.

It is also not at all valid for a group of scientists to get together in the darkened room of an Academy of Sciences somewhere and there determine by consensus among themselves whether Quantum Physics is factual or not. Neither is it valid for scientists to congregate in legislative halls and from there declare that the world should function as deemed fit by them (for example, creationists from Kansas wrought a legal controversy with the intention that their ideology be accounted for as something scientifically verified... when, obviously, their ideology was “unscientifically” verified by its correspondence with biblical myth). To come to a conclusion or theory, scientists are obliged ALWAYS to found their theories on verifiable facts, on real evidence, and NEVER simply on ideas or indeed on a consensus of one or more of our - from time to time -rather unscientific authorities.

No scientist should be accredited simply by dint of his/her academic degree or reputation; nor by their authority or by dint of governmental position. It matters not if he/she is a king, queen, president, or the best teacher or scientist on the planet.

Every thing that is intended to be divulged or disclosed, orally or in writing, in relation to scientific information, has to be properly substantiated by means of the SCIENTIFIC METHOD in any of its modalities.

Read the next extract taken from a news article and discover the word which aligns most closely with dogmatism:

“The most authoritative report on climate change to date will be released tomorrow…”

Believe it or not, the report is from the European Space Agency, released February 1, 2007. It talks about a meeting of politicians and scientists in France and presents them as the supreme authority on climatic change. Of course, people know that climate change is real and that the climate has been changing for millions of years, but the ESA places emphasis on the term “most authoritative” so as to more easily persuade the public into believing the report—which blames human activity as the cause of climate change—has been produced systematically by the world's leading authorities on climate and is, therefore, indisputable. This is another case of an Irrefutable Hypotheses, but served up here with a high dose of dogmatism to help deceive the public.



When I presented, in Mexico, my theory on the origin of life on Earth, a scientist writing for a local newspaper, opined that my theory was extremely weak, but other than that, he offered no further explanation. Knowing he was a scientist, I was interested to find out what his point of view was, so I wrote and asked him. Several weeks passed by before I received from him an angry reply, saying that my theory diverges from the mainstream and that he was free to choose what to believe and what not to believe. I politely answered him by explaining that factual sciences are not a matter of believing or disbelieving in a specific issue, nor are they concerned with being congruent or otherwise with mainstream thought, but on being based on facts. I have not had a reply back from him since my last message.

What does the term “mainstream” mean? Webster’s dictionary defines "mainstream" as a prevailing current or direction of activity or influence. For example, on issues of climate, the mainstream currently holds that human beings are responsible for causing global warming. The mainstream on the origin of species, or speciation, places all its trust in Darwinian Evolution. The mainstream on the origin of life on Earth relies heavily on the belief that photosynthetic organisms were not the first living beings, even when this idea (it is not just based on facts and anecdote) flies in the face of logic. Mainstreams have been wrong in the past and they can be wrong in the present and in the future. That is why the quest for scientific truth, often takes the form of a quest against prevailing mainstream orthodoxy.

We all remember the case of the Medieval scientists who sustained the fantastic mainstream orthodoxy of a flat-Earth. Well, as time passed, it turned out they were wrong, and that a small handful of scientists, who had put the facts on the right track to a spherical Earth, were right. These righteous scientists, who succeeded where others had failed, were never “mainstream” scientists of their time. On the contrary, they had to struggle against and overcome the mainstream, so the journey of scientific discovery could move forward.

A more recent example of a prevailing scientific consensus being overthrow is that of Eugenics. Eugenics is in many ways very similar to climate change. Genetics was the hot new science in the 1920’s, confirming Darwin’s theory of evolution. The proponents of eugenics were led to believe that “bad genes” were a threat to mankind, just as climate scientists today are led to believe that certain atmospheric trace gases are “bad gases”. (Note by TS)

To conclude, sometimes the scientific mainstreams are right, but they can also be wrong. To endure, a scientific mainstream must be based on facts, not on feelings, beliefs, or compromises. Mainstreams that base themselves simply on thoughts are a primary reason why modern science is loosing ground to the adherents of antiscience. If scientists dedicated to testing the feasibility of all the theories of all the mainstreams ceased to exist, then science would become static and quasi-religious. Fortunately, all scientific theories can be tested and adapted to new discoveries.



I have come to realize, through diverse dialogues I have had, that many people who should no better are mostly ignorant of the meaning of science and consequently of how one can adopt a scientific attitude.

Someone wrote to us recently at Biologycabinet criticizing our article on Silicon-based life. The person used the argument that we were wedded to terrestrial matters, to the well-known, and that we had failed to take into account that Silicon proteins and living beings made of Silicon could exist in other parts of the Universe. We answered our critic politely pointing out that so long as we had no knowledge of the existence of proteins not based on Carbon or of the existence of Silicon-based living beings, we could not speculate on the matter, not even to take into account the possibility of their existence. Our answer was based on RATIONAL THINKING and SCIENTIFIC REASONING, that is to say, on factual fundamentals.

What is scientific reasoning? It is not easy to describe in a single line, given that scientific reasoning or rational thinking is constructed from several principles:

1. Scientific reasoning is based on observations of nature. It is thus, because, according to the theory of truth, nature is the source of reality.

2. Scientific reasoning is based on natural facts which are susceptible to being observed or noticed by any person, either through one’s natural senses or aided by suitable tools.

3. Scientific reasoning is based on repetitive natural facts; that is to say, on facts that happen with sufficient frequency that the occurrence of those facts can be corroborated by people other than the first observer.

4. Scientific reasoning generates statements that must be susceptible to rigorous verifications, if the conclusions of those statements are not susceptible to being analyzed by other scientists, then those statements cannot be considered as scientific theories.

5. Rational thinking must be congruent with observed reality.

6. Rational thinking never generate conclusions from simple ideas, but ideas from observable

7. Ideas generated by rational thinking or by scientific reasoning are reserved to the hypothetical plane, so long as those ideas have their origin in observable facts.

8. When an idea is generated from observable facts and is verified as factual, it is reserved to the theoretical plane, as long as that idea has been confirmed empirically.

9. If any argument generated by human reasoning cannot be submitted to analysis or verification, and if that argument is not open to scientific refutation, then such argument cannot be considered as scientific reasoning.

One can apply these rules to any argument being put forward as scientific knowledge, and verify if that argument has been generated through scientific reasoning. The best way to do it, but by no means the easiest way, is by confronting that argument with texts of doubtless good reputation; for example, from scientific journals and books from Publishers of good standing. If we find things in the literature, we must corroborate them through further scientific reading and so on.

Be especially careful with information you find on the Internet. Much of what is presented as scientific knowledge on there is false. Trust only information provided by well known Institutions, like NASA, ESA, the Universities, your School, well-known organizations (like Biocab, AAAS, NYAS, NAS, etc.), well known on line scientific journals (like Scientific American, Physics Today, etc.) and on line articles written by serious scientists.

How do we know who the serious scientists are? Well, serious scientists are the one who ALWAYS append to their articles the bibliographical cards or resources to which they have referred when writing their reports or publish them on their Websites. You can for sure collate bibliographical cards provided by serious professional and easily know if the information has been distorted, misunderstood, if it exists or if the information has simply been invented.

Always remember, scientific knowledge is based on EVIDENCE which can be verified by any person armed with the appropriate tools for the job. The latter implies SCIENTIFIC REASONING and RATIONAL THINKING.

AUTHOR: Nasif Nahle
©Biology Cabinet. May 23, 2000. New Braunfels, TX.



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"If it is not open to disproof, it cannot be science." (Cecily Cannan Selby. Update: NYAS).







SCIENCE (Published on May 20, 2000)
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Published on May 20, 2000Update: February 05, 2008