Here is all the logic I think proper to employ in my reasoning; and perhaps even this was not very necessary, but might have been supplyd by the natural principles of our understanding.  Our scholastic head-pieces and logicians shew no such superiority above the mere vulgar in their reason and ability, as to give us any inclination to imitate them in delivering a long system of rules and precepts to direct our judgment, in philosophy.  All the rules of this nature are very easy in their invention, but extremely difficult in their application; and even experimental philosophy, which seems the most natural and simple of any, requires the utmost stretch of human judgment.  There is no phaenomenon in nature, but what is compounded and modifyd by so many different circumstances, that in order to arrive at the decisive point, we must carefully separate whatever is superfluous, and enquire by new experiments, if every particular circumstance of the first experiment was essential to it.  These new experiments are liable to a discussion of the same kind; so that the utmost constancy is requird to make us persevere in our enquiry, and the utmost sagacity to choose the right way among so many that present themselves.  If this be the case even in natural philosophy, how much more in moral, where there is a much greater complication of circumstances, and where those views and sentiments, which are essential to any action of the mind, are so implicit and obscure, that they often escape our strictest attention, and are not only unaccountable in their causes, but even unknown in their existence?  I am much afraid lest the small success I meet with in my enquiries will make this observation bear the air of an apology rather than of boasting.

If any thing can give me security in this particular, it will be the enlarging of the sphere of my experiments as much as possible; for which reason it may be proper in this place to examine the reasoning faculty of brutes, as well as that of human creatures.

SECT.  XVI OF THE REASON OF ANIMALS

Next to the ridicule of denying an evident truth, is that of taking much pains to defend it; and no truth appears to me more evident, than that beasts are endowd with thought and reason as well as men.  The arguments are in this case so obvious, that they never escape the most stupid and ignorant.

We are conscious, that we ourselves, in adapting means to ends, are guided by reason and design, and that it is not ignorantly nor casually we perform those actions, which tend to self-preservation, to the obtaining pleasure, and avoiding pain.  When therefore we see other creatures, in millions of instances, perform like actions, and direct them to the ends, all our principles of reason and probability carry us with an invincible force to believe the existence of a like cause.  It is needless in my opinion to illustrate this argument by the enumeration of particulars.  The smallest attention will supply us with more than are requisite.  The resemblance betwixt the actions of animals and those of men is so entire in this respect, that the very first action of the first animal we shall please to pitch on, will afford us an incontestable argument for the present doctrine.