Firstly it is important to consider what is being asked here. As I see it this question consists of two parts. Firstly, what did Jefferson mean by happiness? Secondly, what is the relevance of the word ‘pursuit’ in relation to Jefferson’s understanding of happiness. Here I will examine what Jefferson likely meant by ‘Happiness’, then consider the broader question. I draw mainly from Darrin M. McMahon’s monograph ‘Happiness: A History.’ In his chapter titled ‘Liberalism and Its Discontents’ he discusses the variety of perspectives on happiness in 19th century America and Europe.

McMahon notes firstly that happiness was actually used more than once in the declaration of independence. It appears in the finished document in one other place, but was also used a third time in a draft of the document. The first usage and the one which most people are familiar with reads as follows:

“We hold these truths to be self evident: that all men are created equal; that they are endowed by their creator with unalienable rights; that among these are life, liberty & the pursuit of happiness.” (McMahon, 315)

The second instance comes only shortly after this. The text continues:

“That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness.” (McMahon, 315)

McMahon notes that while the Continental Congress allowed both of these instances of the word, and offered no commentary regarding their usages, they did strike a sentence containing the word from Jefferson’s original draft. That line read:

“The road to happiness & to glory is open to us too.” (McMahon, 315)

Why the Continental Congress removed this line is difficult to say, but we aren’t after the Continental Congress’s take on Happiness, we are after Jefferson’s. What can these three usages tell us about Jefferson’s take on happiness?

From these three lines It can be said, at the very least, that Jefferson viewed happiness as sufficiently important that the authority of a government should hinge upon it. This can be seen especially in the language surrounding the second usage of the word. Should a government become “destructive of these ends [this includes happiness], it is the right of the people to alter or abolish it…” That he pairs the pursuit of happiness with life, liberty, safety and glory indicates that he viewed life, liberty, safety and glory as concepts sufficiently distinct from happiness such that he needed to include each term.

In another instance Jefferson described the material which he used to draft the declaration. In a letter he wrote that “its authority rests then on the harmonizing sentiments of the day, whether expressed in conversation, in letters, printed essays, or in the elementary books of the public right, as Aristotle, Cicero, Locke, Sidney…”(McMahon, 316) This suggests that we might be able to gain some insight into Jefferson’s views on happiness by examining what these four philosophers had to say on happiness.

Locke in particular has been accused of inspiring Jefferson’s phrase “Life, Liberty and the Pursuit of Happiness” by his having written the phrase “life, liberty and property.” This would suggest that Jefferson meant ‘Property’ when he said ‘happiness’. However, McMahon also points out the major problem with that argument. Chiefly that Locke never actually wrote the phrase ‘life, liberty and property.’ He rather wrote the phrases ‘life, liberty and estate’ and ‘life, liberties, and fortunes’ in his Second Treatise. Furthermore, Locke makes no mention of happiness in his Second Treatise. (McMahon. 317.) Locke did however mention happiness in an essay titled Essay Concerning Human Understanding. If Jefferson’s understanding of happiness was influenced by Locke it seems more likely that it was influenced by this essay as it was the only one of Locke’s to actually discuss happiness.

In Essay Concerning Human Understanding Locke describes happiness as “a natural and wholesome part of a divinely orchestrated world in which human beings are led along by pleasant sensations, ending, if they get it right, in God.”(McMahon, 317) This was a common sentiment during this period.

If Jefferson took Locke’s version of happiness seriously than he likely conceived of happiness as at once a matter of pleasure and a matter of religious devotion. However, Jefferson also cited three other philosophers each of whom incidentally has their own interpretation of happiness. I’ll attempt to address them each briefly.

Aristotle argued that happiness was the product of a good life. Of happiness he wrote:

“We may define happiness as prosperity combined with virtue; or an independence of life; or as the secure enjoyment of the maximum of pleasure; or as a good condition of property and body…” (McMahon. 46.)

Aristotle adds, in an attempt to produce an exhaustive list of happiness’s components, that it includes:

“good birth, plenty of friends, good friends, wealth, good children, plenty of children, a happy old age, also such bodily excellences as health, beauty, strength, large stature, athletic powers, together with fame, honour, good luck and virtue.” (McMahon. 46.)

An exhaustive list to be sure, but one which Jefferson was likely at least indirectly familiar with considering his contention of Aristotle’s importance to the period in which he himself lived. As such, Jefferson likely incorporated some version of Aristotle’s description of happiness alongside the more religious one conceived of by Locke.

Algernon Sydney, the third name Jefferson cited above, for his part likely would have sided roughly with Locke’s accounting of happiness. Sydney was “a seventeenth-century English theorist who was executed on suspicion of plotting to overthrow Charles II”(McMahon. 325.). McMahon notes that Sydney was part of a tradition of classical republicanism which “conceived liberty in more active terms as direct public participation…classical republicans understood happiness, with strong Stoic inflections, as a civic virtue.” (McMahon. 324.)

Cicero, the fourth and final name which Jefferson cited as having inspired the declaration of independence, was a Stoic philosopher. They were very much in line with aristotle’s conception of happiness and put special emphasis on happiness as a matter of virtue. Seneca, another Greek stoic wrote “The happy man is content withhis present lot, no matter what it is.” (McMahon. 55.) Cicero however pushes that to an extreme by suggesting that “the man of perfect virtue will be happy even under torture, even on the rack.”(McMahon.55.)

The two liberal voices for their part indicated that happiness was at once a matter of pleasure, religious devotion and virtue. The two classical voices for their parts especially stressed the importance of virtue to happiness. From these sources we can reasonably assert that Jefferson’s meaning of happiness had something to do with each of these qualities. That is to say that we might replace the phrase “pursuit of happiness” with the much more cumbersome phrase “pursuit of pleasure, religious devotion and virtue.” McMahon notes similarly that ‘The “pursuit of happiness,” it should now be clear, was launched in different, and potentially conflicting, directions from the start, with private pleasure and public welfare coexisting in the same phrase.” (McMahon. 330.)

What then of the phrase Pursue? McMahon offers some comment on this as well. He points out chiefly that the meaning of the word pursue had a slightly different meaning during Jefferson’s time. The two contemporary usages he points to which read as follows in Dr Johnson’s Dictionary of the English Language:

To Pursue…1. To chase; to follow in hostility.

Pursuit…1.The act of following with hostile intention. (McMahon. 320.)

McMahon adds that “To pursue happiness, in this sense (to follow with hostile intention), was in some measure to engage in a repeatedly frustrating game, in which desire could never be permanently satisfied.”(Mc.Mahon. 321.)