The first, that we not forget our felicity in knowledge as we forget our mortality:

The second, that we make application of knowledge to give ourselves repose and contentment and not distaste or repining:

The third, that we do not presume by the contemplations of nature to attain to the mysteries of God.

During his years of political service, Francis Bacon published a collection of essays and several works on reorganizing the natural sciences. The most important of the latter was the Novum Organum, written in 1620. The title is taken from Aristotle's Organum, meaning "logical works", and accordingly signals a radical departure from the traditional method of scientific inquiry. This work, along with the rest of his published and unpublished philosophical writings, can be seen as part of his grandiose plan to reorganize the sciences. This reorganization involved a projected, and largely unfinished, six-part work entitled Instauratio. The plan involved:

A new division of the sciences,

A new method of scientific inquiry,

A collection of scientific observations and facts,

Examples of the new method,

Philosophical precursors to the new philosophy, and

The new philosophy itself resulting from the application of the new method.

The Novum Organum, a work which may be viewed as a preliminary of division two of the Instauratio, is divided into two parts. The first part, Book I, deals with the need for an inductive system, and the second, Book II, deals with the applications of such a method.

In Book I, Bacon grounds the human understanding in observation and experience which leads to a harsh rejection of the popular Aristotelian a priori, deductive method. The alternative he proposes is an a posteriori, inductive approach.

Bacon's idea of such an approach is made metaphorically in one of his aphorisms (XCV). Commonly used symbols for understanding nature are those of the ant and spider. The ant experiments by collecting and using. This method symbolizes the human tendency to use facts without clearly understanding them. The spider, on the other hand, does not experiment but produces webs from its own substance, symbolizing the tendency to formulate ideas and facts by thought alone. The method for understanding nature Bacon holds to be the most significant is that of the bee which gathers the pollen of the flower, changes it through its own efforts, and then uses it. According to Bacon, we must observe and collect experiences, analyze exactly what we know, then act on the most reliable facts.

Bacon also distinguishes between the Anticipation of Nature and the Interpretation of Nature. Few reasons exist for believing in the Anticipations. They are generalizations which are easily believed. The Interpretations are based on various data which enables one to master things. The Interpretations are not easily accepted, but are clearly the most stable method of analyzing nature.

One of the most important of Bacon's beliefs, and the one for which he was most widely known, is his idea of the Four Idols. These Idols are what he believes to be the primary hindrance to our efforts in studying nature. The first are the Idols of the Tribe. These have their foundation in human nature. Humans falsely assume their perceptions are based on universals when in fact their perceptions are based purely on individual views. The second are The Idols of the Cave. These are distinguished from the Idols of the Tribe and deal with the individual, for every person perceives things by means of his own individual nature. One's personality and experiences make them see things in ways which they may not be. The third are The Idols of the Marketplace. These Idols deal with the language of people. Because of the errancy in choosing which words to use in order to convey a certain meaning, one may express the wrong idea to another. The fourth are The Idols of the Theatre. These Idols deal with the dogmas of all philosophies. What is already established and believed to be true may not be. One cannot be biased toward any popular belief system.

In Book II, Bacon describes the part of his method involved with gathering facts. Aristotle contended that science involves the discovery of a phenomenon's causes. For example, to understand the nature of heat, we must discover the causes of heat. For Aristotle, this process involves uncovering all four of its causes: formal, material, efficient, and final. In spite of Bacon's harsh rejection of Aristotle's deductive syllogism, Bacon follows Aristotle by seeing science as the discovery of causes, and, specifically, formal causes. According to Bacon, the formal causes of a thing (that is to say, its "forms") are its physical properties. For example, the form of heat is the violent, irregular motion of particles. Thus, by discovering this form of heat, we reveal the scientific nature of heat itself. For Bacon a good set of rules of scientific method will reveal the forms of a thing. He notes four things that we should expect from a good set of such rules. First, it will not deceive him; second, it will not tie him down to any particular mode of operation; third, it leads to action; and fourth it will lead to the discovery of the necessary and sufficient conditions of a given nature (such as heat). The forms, then, are just those necessary and sufficient conditions (such as violent, irregular motion of particles).

Having maintained the job of science is to uncover a thing's forms, Bacon finally explains the inductive method by which this uncovering is performed. Bacon's specific inductive methodology is presented in what he describes as the three "Tables of Comparative Instances" which involve presence, absence, and degrees. The "Table of Presence" (agreement) involves examining instances in which the same phenomena are present, and noting what other circumstances are in common. For example, to understand the forms involved with heat, we examine all hot things and see what circumstance is in common, such as irregular motion of particles. The second table, the "Table of Absence," involves examining instances in which a phenomenon is absent, and noting what circumstances are in common. Thus, to understand heat, for example, we must also examine a list of cold things and discern what features are irrelevant to the production of heat, such as density. Finally, the "Table of Degrees" involves examining instances in which a phenomenon is present in varying degrees, noting what circumstances also vary. For example, to understand heat we must observe things at different temperatures and note what circumstances are present in varying degrees, such as varying speeds in the irregular motion of particles. By constructing the three "Tables of Comparable Instances" we eliminate irrelevant properties, such as density, and pinpoint the essential properties, such as the irregular motion of particles. This, according to Bacon, is true induction. Bacon recognized that we cannot examine an endless number of instances for the three tables. At some point we must stop and survey the instances so far. This review he calls the "first vintage."

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