The human mind feels restless and dissatisfied under the anxieties of ignorance. It longs for the repose of conviction; and to gain this repose it will often rather precipitate its conclusions than wait for the tardy lights of observation and experiment. There is such a thing, too, as the love of simplicity and system, a prejudice of the understanding which disposes it to include al the phenomena of nature under a few sweeping generalities, and indolence which loves to repose on the beauties of a theory rather than encounter the fatiguing detail of its evidences.
They [trees] hang on from a past no theory can recover. They will survive us. The air makes their music. Otherwise, they live in savage silence, though mites and nematodes and spiders teem at their roots, and though the energy with which they feed on the sun and are able to draw water sometimes hundred of feet up their trunks and into their twigs and branches calls for a deafening volume of sound.
Our concepts of the empirical world are fundamentally controlled by the character of our perceptual experience and by the introspective access we enjoy to our own minds. Thus our concepts of consciousness are constrained by the specific form of our own consciousness, so that we cannot form concepts for quite alien forms of consciousness possessed by other actual and possible creatures. Similarly, our concepts of the body, including the brain, are constrained by the way we perceive these physical objects; we have, in particular, to conceive of them as spatial entities essentially similar to other physical objects in space... But now these two forms of conceptual closure operate to prevent us from arriving at concepts for the property or relation that intelligibly links consciousness to the brain. For, first, we cannot grasp other forms of consciousness, and so we cannot grasp the theory that explains these other forms: that theory must be general, but we must always be parochial in our conception of consciousness. It is as if we were trying for a general theory of light but only could grasp the visible part of the spectrum. And, second, it is precisely the perceptually controlled conception of the brain that we have which is so hopeless in making consciousness an intelligible result of brain activity. No property we can ascribe to the brain on the basis of how it strikes us perceptually, however inferential the ascription, can be the crucible from which subjective consciousness emerges fully formed. That is why the feeling is so strong in us that there has to be something magical about the mind-brain relation.
Finding facts in actuality is less rewarded than developing a theory of law that explains the facts, and herein lies an enticement. In making sense out of the unruly substance of nature, and in trying to get there first, a scientist is sometimes tempted to play fast and loose with the facts in order to make a theory look more compelling than it really is.
War is an act of force, and to the application of that force there is no limit. Each of the adversaries forces the hand of the other, and a reciprocal action results which in theory can have no limit.
Mankind likes to think in terms of extreme opposites. It is given to formulating its beliefs in terms of Either-Ors, between which it recognizes no intermediate possibilities. When forced to recognize that the extremes cannot be acted upon, it is still inclined to hold that they are all right in theory but that when it comes to practical matters circumstances compel us to compromise.
The gap between theory and practice is a wide one.
The first principle asserts that at least some mental events interact causally with physical events... The second principle is that where there is causality, there must be a law: events related as cause and effect fall under strict deterministic laws... The third principle is that there are no strict deterministic laws on the basis of which mental events can be predicted and explained... from the fact that there can be no strict psychophysical laws, and without our other two principles, we can infer the truth of a version of the identity theory, that is, a theory that identifies at least some mental events with physical events.