What were Leibniz's views on embryology?

Gottfried Leibniz believed in preformationism, the theory that all living things had been created at once so that their offspring unfold from completely formed seeds, or homunculi in the case of humans and animunculi for animals. Some preformationists believed that the whole of successive humanity must have been present in Adam's testicles from the time he was in the Garden of Eden, while others held that they were in Eve's ovaries. These two views were called "spermism" and "ovism," respectively.

The opposing theory to preformationism was epigenesis, or the idea that embryos developed in time. However, before a true knowledge of heredity or conception, together with Christian belief that mere matter could not by itself become a complex living organism, epigenesis did not seem plausible given available evidence.

Antoni van Leeuwenhoek, a highly skilled Dutch lens grinder, was able to construct microscopes that magnified items 200 times. Around 1700, after having seen bacteria, he reported viewing both male and female sperm:

I have often observed the sperm of a healthy man without waiting for it to become corrupt or fluid/watery, five or six minutes after ejaculation. I have noticed a large number of small animals, I think it must be more than a thousand, on an area no larger than a grain of sand.

Gottfried Leibniz believed that all human beings were predetermined as homunculi from the beginning of time. In other words, each human being was completely formed before he or she was an embryo in the womb (iStock).

Gottfried Leibniz believed that all human beings were predetermined as homunculi from the beginning of time. In other words, each human being was completely formed before he or she was an embryo in the womb (iStock).

Leeuwenhoek reported having seen tiny animals with completely formed features in pond scum and tooth plaque, as well as in the sperm of over 30 animals. He was made a member of the Royal Society, and his descriptions of miniature worlds within worlds were accepted as evidence for preformationism, as well as the original creation of everything in the universe, all at once, by God.

What is metaphysical idealism?

Metaphysical idealism is the position—going back to the pre-Socratics and brought to fruition by Plato in the ancient world—that what is ultimately real is something non-material and not apparent to the senses. Insofar as God was believed to be both non-material and most real, all Christian philosophers were "idealists," but the term is usually reserved for those who posited mind or other nonmaterial substances and things as more real than matter in the natural world.

What were some of Leibniz's original contributions to philosophy?

Leibniz's major works include The Monadology (1714), Discourse on Metaphysics (1686), Theodicy (1710), and The Leibniz-Clarke Correspondence (1714-1715), as well as political writings and a large body of unedited material. Leibniz had a very complex view of the universe that defied common sense, was theoretically fascinating, and preserved core Christian beliefs. His philosophical writings were highly complex and had their own terminology. He claimed that his philosophy was based on these general principles: principle of identity, principle of the best, principle of sufficient reason, metaphysically necessary principles, principles of order, principles of causation, and the principle of the natural. In addition to this, he used the idea of monads as the basic unit of what was real.

How did Leibniz define his principles?

Leibniz based his philosophy on the following principles:

The principle of identity—This is the law of necessary truth and non-contradiction. A is A and never not-A. The opposite of a necessary truth is a contradiction.

The principle of the best—A contingent truth can have an opposite that is not a contradiction. God, who is perfectly wise, good, and powerful did not have to create the world. But he chose to do so and because He chose it, it is the best possible world.

The principle of sufficient reason—Everything that exists or occurs must have a reason that was sufficient to bring it about.

Metaphysically necessary principles—Leibniz had a number of these, which included: everything possible demands to exist and it will exist unless pre-

Who was Dr. Pangloss?

The brilliant French satiric essayist François-Marie Arouet de Voltaire (1694-1778) pilloried Leibniz's philosophical optimism with the character of Dr. Pangloss in his novel Candide. The character Candide is the illegitimate nephew of a baron who starts out life in luxury, with Dr. Pangloss as his teacher. ("pan" is Greek for "all" and "gloss" means "tongue, speech, and words," so that Dr. Pangloss translates as "Dr. Alltalk.")

Dr. Pangloss teaches the "metaphysico-theologo-cosmolonigology" to Candide. This teaching is a caricature of Leibniz's and the poet Alexander Pope's philosophical optimism, which Voltaire found very difficult to reconcile with real human suffering, such as the devastation caused by the 1755 Lisbon earthquake and the oppression of the ancien régime in pre-revolutionary France.

The view of philosophical optimism held that because God is good, everything in the world must be good, as well. It is, in fact, the best world it could be, and everything in it, including what appear as evil to us, is, in the grand scheme of things, inevitable and for the best. Here's a sample of Voltaire's satire in which Dr. Pangloss expresses his belief:

"It is demonstrable," said he, "that things cannot be otherwise than as they are; for as all things have been created for some end, they must necessarily be created for the best end. Observe, for instance, the nose is formed for spectacles, therefore we wear spectacles. The legs are visibly designed for stockings, accordingly we wear stockings. Stones were made to be hewn and to construct castles, therefore My Lord has a magnificent castle; for the greatest baron in the province ought to be the best lodged. Swine were intended to be eaten, therefore we eat pork all the year round: and they, who assert that everything is right, do not express themselves correctly; they should say that everything is best.

vented; activity is essential to substance; and states of things remain unless or until there is a reason for them to change.

Principles of order—These consisted of three laws of order: the law of continuity, the law that every action involves a reaction, and the law that cause and effect are equal.

Efficient and final causation—Efficient causes are what immediately make things happen, whereas final causes are the ends or goals of higher substances. The entire realm of efficient causation is designed to serve the realm of final causation.

Principle of the natural—Everything that God allows to exist and happen, he chooses from what is natural; otherwise He would constantly be performing miracles. What is natural is always in between what is essential or necessary and what is accidental.

What was Leibniz's monadology?

Like René Descartes (1596-1650), Leibniz thought that the basic unit of existence was substance. But whereas Descartes posited two primary kinds of substances—mind and matter—Leibniz posited one immaterial kind of substance, which had many, many instances that he called "monads." Monads, according to Leibniz, are indivisible units of psychic or mental or spiritual force, each one of which perceived all of the other monads as an aspect of its own inner states.

Each monad had an organic body that "mirrored" what was happening in other monads, but not as a direct effect. That is, like a cell containing all of the chromosomes and genes of the animal of whose body it is a part, for Leibniz each monad contained within itself complete information about the rest of world. In addition, every monad contained its own future states, and of course, within those future states would be the monad's perception of the future states of every other monad. This world system of monads was created by God and its main feature is the pre-established harmony that results in human perceptions of direct inter-action and inter-relationships.

Monads form colonies and colonies of colonies with dominant monads at different levels of organization. These collections of monads constitute real physical existence. Both space and time are abstractions and not substances. Space, according to Leibniz, is the form of possible coexistences; and time is the form of possible successive existents (things that exist).

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